MODERN CONSTRUCTION ROOFS ANDREW WATTS
INTRODUCTION 4 METAL Modern Construction
(1) Metal standing seam
3
2
1 32 GLASS 34
64 CONCRETE
(1) Greenhouse glazing and
(1) Concealed membrane 110
Series
4
Site-based method
Aims of this book
5
Prefabricated methods
Greenhouse glazing
Structural joints
Sealed and ventilated roofs
Modern roof glazing
Parapet upstands
Roof openings
Capped systems
Balustrades and plinths
Introduction
6
Capped systems
66
Ridges and valleys (1) An overview of roof systems
108
Materials
Rainwater outlets (2) Silicone-sealed glazing
Eaves and parapets 8
Penetrations for pipes and ducts
and Rooflights
72
Metals
(2) Profiled metal sheet
Silicone-sealed systems
(2) Exposed membrane
Glass
Profiled metal decks
Junctions
Polymer-based membranes
Concrete
as substrates
Use of capped profiles
PVC membranes
Timber
Profiled metal roof sheeting
Rooflights
FPO (TPO) membranes
Plastics
Sealed and ventilated methods
Fabrics
Twin skin construction
(3) Bolt fixed glazing
Ridges
Generic structural
Parapets and upstands
Openings
support methods
Ballasted roofs
Eaves and parapets
Supporting brackets
Ridges and valleys
Bolt fixings
(3) Planted
Arrangement of bolt fixings
Planted roof components
Glazed units
Soil depth
(2) Working with manufacturers, fabricators and installers
16
(3) Performance testing of roofs
(3) Composite panels 18
40
46
Mechanically fixed method 78
Single wall composite panels Twin wall panels
Water penetration tests
Ridges
Wind resistance tests
Verges
Base of glazed roof
Impact resistance test
Eaves
External and internal folds
Dismantling of sample
Parapets and valley gutters
Small glazed rooflights
(4) Bolt fixed glazing : Pitched roofs and rooflights
84
(4) Rainscreens
52 (5) Bolt fixed glazing:
Panel arrangement
Davits and monorails
20
Parapets
Trolley systems
26
Monopitch ridges and verges
Twin wall roofs
90
Davit systems
Roof geometry
(6) Bonded glass rooflights 96
Monorails
Roof soffits
Generic conical rooflight
Trolley systems
Generic rectangular rooflight (5) Metal canopies Bolt fixed panels
58
Generic monopitch rooflight Glass roof decks
Fixed metal louvre canopies Electrically operated louvres
(7) Glazed canopies
102
System assembly Four edge restrained canopy Bonded glass canopies
Roof junctions Rainwater outlets Balcony planters
Larger rooflights maintenance systems:
Bonded fixing method
Overflows
Air infiltration test
(4) Roof-mounted
116
122
4 TIMBER
5 128 PLASTIC
(1) Flat roof : Mastic asphalt coverings
CONTENTS
(1) GRP rooflights 130
6 160 FABRIC 162
174 REFERENCES
(1) ETFE cushions
176
Photo references
194 194
Eaves and upstands
Cushions
Authorship
195
Warm and cold roofs
Verges
Air supply
Bibliography
196
The material
Abutments
The material
Index
198
Warm roof build-up
Sliding roof panels
Fabrication
Solar protection
Durability
Upstands
(2) GRP panels and shells 168
Eaves and verges
Smaller panels and shells
Penetrations
Larger panels and shells
Gutters and rainwater outlets
Performance in fire (2) Single membrane : Cone-shaped roof
182
Fabric roof principles (2) Flat roof. Bitumen-based sheet membranes
136
Fabric types Comparison of types
The material
Thermal insulation
Roof build-up
Acoustics
Solar protection
Durability
Fixing methods
Performance in fire
Parapet upstands
Condensation
Junction with tiled roof (3) Single membrane :
Eaves and verges
Barrel-shaped roof (3) Pitched roof :Tiles
142
Membrane roof fabrication
Plain tiles
Membrane roof edges
Interlocking tiles
Suspension points
Ventilation
Membrane folds
Eaves Ridges Verges Hips and valleys Abutments (4) Pitched roof : Slates
148
Roof folds Vents Monopitch ridges Dormer windows Abutments (5) Pitched roof : Metal Standing seam cold roofs Eaves and valley gutters Ridges and abutments Penetrations Metal tiled roofs
154
188
MODERN CONSTRUCTION SERIES
The series is based around the Modern Construction Handbook.Themes of each chapter from the MCH are developed to provide detailed design guides for facades, roofs, materials and fittings. An additional volume of details brings together drawn technical information. Books in the series discuss component design, building assembly, craftsmanship, as well as structural and environmental issues from the MCH.
AIMS OF THIS BOOK
Modern Construction Roofs is a textbook for students and young practitioners of architecture, as well as students of structural and environmental engineering who wish to broaden their study beyond the information provided in the Roofs chapter of the Modern Construction Handbook. It shows the principles of the main roof types used today and illustrates this through typical generic details, together with a built example, that can inform a design at a more detailed stage. The six chapters examine roofs from the standpoint of the primary material used in their construction, from metal to glass, concrete, timber, plastics and fabrics. Each set of three double page spreads explains a specific form of construction which is accompanied by drawn and annotated details.Throughout the book, built examples by high profile designers are used to illustrate specific principles. As is the case in the Modern Construction Handbook the techniques described can be applied internationally.
INTRODUCTORY ESSAYS
These essays discuss two issues related to roof design: design development, and provisions for maintenance access.There is an increasing tendency to conceal roof gutters and pipes and to integrate them into the depth of the roof construction. Access systems for cleaning and maintaining roofs, as well as equipment mounted on a roof for cleaning facades beneath, has developed considerably over the last 10 years. In addition to cradles hung from the roof on fixed jibs or moving on tracks, the use of abseiling has increased in popularity since the 1980's. The higher levels of safety used in abseiling make it easier to clean roofs and facades of complex geometry without the need for highly visible ladders and cradles.This has considerable advantages for glazed roofs, inclined metal roofs and fabric structures.
METALS CHAPTER
The Metals Chapter discusses the use of metal sheet in roofs both as a substrate and as a watertight covering.When used as a substrate, in the form of profiled metal decking or composite panels, a waterproof membrane can be formed in different materials. Used as a covering material, metal sheet can be used in standing seams, profiled sheet and rainscreens. Solar shading devices formed from metal are also discussed.
GLASS CHAPTER
The Glass Chapter sets out the use of the material as both rooflights and as large glass roofs. Stick framed rooflights and glazing systems are related to those used for walls, but are usually fixed with pressure plates on the two sides parallel with the line of slope. Bolt fixed glazing systems for rooflights and roofs follow principles used in wall construction. Bonded glass decks and rooflights are a development of glass block details, which are also discussed. Finally in this
MCR_ 4
INTRODUCTION chapter, glazed canopies are discussed, focusing on those that use point fixings with a minimum of support structure.
CONCRETE CHAPTER
Roof decks constructed in concrete are covered with a variety of waterproof membranes and finishes.When the membrane is applied directly to the concrete, thermal insulation and finishes, such s planting, paving slabs or timber decking, are applied. Construction can also be finished with another roofing system, such as metal standing seams, or rainscreens in other materials. All these types are discussed in this chapter.
TIMBER CHAPTER
Timber roofs are a traditional form of construction that use mainly tiles, slates and shingles in housing projects. In recent years, the increased use of metal sheet on timber roofs has led to an increase in more complex geometries that do not need to follow the principles of those traditional lapped roofing materials. Flat timber roofs, thin planting and metal sheet, in addition to the more traditional single membrane finishes, are set out here.
PLASTICS CHAPTER
GRP panels have the advantage of providing well insulated translucent panels that are more economic than those in glass.They are much lighter than glass, allowing more visually delicate support structures to be used for these panels. Glass reinforced polyester (GRP) can produce opaque roof forms that are free of joints, forming continuous roof structures such as shells and domes that form a monolithic, lightweight material with a watertight finish on its outside face. All these types are explained in this chapter.
FABRIC CHAPTER
The Fabric Chapter discusses tensile roof structures, air supported types and smaller scale canopies. PTFE membranes can be stretched over supporting structures, typically stainless steel cables with tubular steel supports. PTFE sheet is also used to form inflated 'air pillows' that are supported on an aluminium frame.Their advantage of high thermal insulation and lightness in weight is making them an increasingly preferred option for roof structures.
QUALIFYING COMMENTS
The building techniques discussed and the built examples shown are designed to last for an extended period with a relatively high performance. However, buildings for exhibitions and for temporary use are included since the techniques used have proven to be reliable in both short term and long term. In addressing an international readership, references to national legislation, building regulations, codes of practice and national standards have specifically not been included. This book explains the principles of accepted building techniques currently in use. Building codes throughout the world are undergoing increased harmonisation because of increased economic and intellectual globalisation. Building components and assemblies from many different countries are often used in a single building. Since building codes are written to protect users of buildings by providing for their health and safety, good construction practice will always uphold these codes as well as assist their advancement.The components, assemblies and details shown in this book describe many of the building techniques used by the building industry today, but this book does not necessarily endorse or justify their use since techniques in building are in a continual state of change and development. Some of the examples shown are highly developed applications of the techniques described.
MCR_5
INTRODUCTION (1) An overview of roof systems Metals Glass Concrete Timber Plastics Fabrics (2) Working with manufacturers, fabricators and installers (3) Performance testing of roofs Air infiltration test Water penetration tests Wind resistance tests Impact resistance test Dismantling of sample (4) Roof-mounted maintenance systems: Davits and monorails Trolley systems Davit systems Monorails Trolley systems
MCR_ 7
An overview of roof systems Light Wing, New York City. Architect:Tom Wiscombe / Emergent.
An essential change in recent years that has
become submerged in a thin film of water
increased flexibility) led to more adventur-
affected roofing systems in all materials is the
running across it, so that the principles of a
ous roof forms without affecting the its
increased visibility of roof designs, with some
second line of defence used in facade design
waterproofing performance.The gradual
forming a continuity with the façade
have a limited application on roofs. Some
move away from the traditional roof with a
beneath.Where roofs were once considered
designs take the idea of the roof as a com-
central ridge led to the use of brighter
to be either of traditional appearance, as
pletely watertight, single layer membrane
colours in paint-based finishes which are
with tiled and slated pitched roofs, or else
and use it to cover the complete external
associated with consumer products, particu-
completely concealed as flat roofs, they are
envelope.This is very much a principle of the
larly cars, rather than the use of traditional
now increasingly considered to be a part of
roof taken down over the walls, rather than
dark colours that imitated traditional materi-
a completely visible envelope design which is
facade design taken over the roof. Both
als such as tiles and slates, or galvanised coat-
as visually important as the external walls,
approaches are taken in sculptural forms
ing on steel sheet. By the 1980's some build-
both in their appearance and their technical
where wall and roof are combined in a sin-
ings even imitated the forms of train car-
performance.The increased performance of
gle design.
riages, with polished stainless steel roof
roofing systems in all materials has led to
Increasingly, roof systems are influencing
cladding and profiled metal that followed
greater experimentation, both technically
facade designs, and facade techniques are
horizontal lines rather than the traditional
and visually.
being incorporated into roof design. Bolt
orientation of the profiled sheet which
fixed glazing, rainscreens, silicone bonding
allows rainwater to drain easily down the
are taking on a single structural form, with
In some recent projects, walls and roofs
and unitised panels are being absorbed into
slope. By the early 1990's profiled metal
the same construction methods, materials
roof design, while ETFE cushions, polymer
roofs were using standing seam joints, which
and detailing used on both walls and roof.
membranes and fabric structures are finding
combined the long span capability of profiled
The increased technical performance and
their way into facade design.
sheet with the visually refined and very
long term reliability of roofing materials of all types has led to a much more ambitious design approach. However, an essential dif-
water tight standing seams which are
Metals A development in metal roofs over the
'zipped' together by machine on site. Since the introduction of 'zip up' sheeting, the dif-
ference between facades and roofs as that
past 10 years has been to improve the visual
ference between profiled metal and standing
facades have rainwater running across their
appearance of all metal roof systems. By the
seam systems has become slightly blurred as
surface, but roofs can be submerged in
late 1970's, profiled metal sheet roofs had
a result of these mixed methods of assembly.
water during rain. A roof has to be com-
added curved eaves and pressed metal cor-
This new 'hybrid' system has a lining panel
pletely sealed in areas where water can col-
ners to provide concealed gutters that gave
system which can be fixed from metal
lect, such as parapet gutters, with the
the roof a strong 'linear' texture that formed
sheets, with some being hung down from
assumption that rainwater will be expected
an important part of the design of industrial
roof level without any scaffolding or access
to remain on the roof if the rainwater out-
buildings.The increased reliability of jointing
platforms required at all.This makes large
lets become blocked. Even pitched roofs
together with the increased use of alumini-
roof spans, particularly at high level, such as
assume that the surface of the roof will
um sheet instead of steel sheet (with its
in covered sports halls, much easier to con-
MCR_ 8
The innovative design and construction of this roof canopy was a result not only of digital technology, but of an equally innovative use of teamwork, where individuals and groups are brought together for a specific project.The working method was as important to the design team as the aspects of design and fabrication.
struct since scaffolding is not required.
to metal roofing systems.They do not use
to achieve the same visual effect. Although
the outer seam as a first line of defence
such panels are a kind of 'virtual' metal roof
in development since the 1980's, with panels
against rainwater penetration but rather as a
rather than being formed entirely from
that provide an internal ceiling finish and
protection to the membrane beneath
metal, they can deal with varying methods of
outer roof covering in single panels which are
against the effects of the sun and to avoid
translucency and transparency in a single
semi-interlocked, with either a lapped metal
maintenance staff walking on the exposed
metal layer that can reveal its depth both
joint between panels or a metal capping that
membrane.This is becoming a visually more
from inside the building and from outside. A
clips over a standing seam-type joint. Com-
appealing alternative to smooth pebbles,
future development of metal rainscreen pan-
posite panels have still not reached the level
which also have the disadvantage of collect-
els might be to use them in conjunction with
of technical ambition of their counterparts in
ing dirt and dust from which vegetation can
a translucent roof such as GRP panels filled
facades.The joint between panels would be
grow. Metal rainscreen panels are required
with translucent thermal insulation, with var-
ideal to serve as drainage gutters to be set
to be sufficiently rigid and resistant to impact
ied amounts of daylight, allowing GRP panels
or even as a second line of defence to an
damage. Composite sheets with a plastic
to be in different colours, to which they
outer seal, as used in curtain walling, with a
core and thin metal outer facings are popu-
would otherwise be susceptible to colour
drained and ventilated slot in the joint where
lar in this regard since they achieve high lev-
fading without the perforated or slotted
water would be released at the base of the
els of flatness and are flexible enough to
metal panels.They could also be used with
roof. Some attempts have been made in this
withstand foot traffic, usually when alumini-
polycarbonate sheets or plastic-based glazing
direction, but much development is needed
um sections are silicone-bonded on the
in acrylic, for example, where the punched
to move this metal system away from an imi-
underside of panels.
metal panels allow a diffused light but where
Composite roof panel systems have been
tation of profiled sheet metal into a complete
A new development is the use of metal
the aging effects on the materials would be
system in its own right. A modest but useful
rainscreens in a mixture of opaque and per-
much less apparent and may even contribute
method of using composite panels is as an
forated or slotted, panels, which may also be
to enhancing the coloured effects.This alter-
insulated structural deck to a separate water-
used in soffit (upside down) conditions. Here
native to a glass roof would allow such roof
proof membrane set on top.While lacking
the panels are more than a semi-decorative
build-ups to be non-linear, even curving in
visibility of the panels, it is very adaptable and
covering to an economic roof covering,
two directions, in the manner of tensioned
economic, with thermal insulation not only
forming part of the expression of the build-
single layer fabric membrane roofs.
filling the voids between peaks and troughs
ing envelope in forming a continuity
of the metal sheet on its underside but also
between different parts of a roofscape, rang-
developments. Since they can also be used
providing structural stability.These composite
ing from covering air extract terminals,
as solar shading, they often can be consid-
roof panels have also been used in facades,
rooflights and gutters to forming a continu-
ered to be small roof structures in their own
where long span cladding panels are required
ous smooth continuation of the facade
right, being able to exploit folding geome-
which are difficult to obtain specifically from
below. Metal rainscreen panels can also
tries, as experiments for future building
proprietary cladding systems.
accommodate complex geometries without
envelopes.The use of CNC-based cutting
having to make individual composite panels
machines, as well as the increasingly eco-
Rainscreen panels are a recent addition
Metal canopies are undergoing major
MCR_ 9
An overview of roof systems Bruges Pavilion. Belgium. Architect:Toyo Ito & Associates.
The design of the structural composite panels, or 'sandwich' panels, underwent much development in the workshop.The extensive use of prototyping allowed an ambitious design to be developed for a relatively small building.
nomic stamping tools to make individual patterns in punched sheets, makes specially pat-
Glass Glass systems have developed consider-
have been in use for the past 25 years, the issue of the water tightness of the horizontal
terned and cut panels for each project easier
ably over the past 25 years in order to
joint has been undergoing continual devel-
to obtain in different materials.
address the issue of improved weather tight-
opment. Glazing bars have been used to
ness. So-called 'patent' glazing originally
support glass down the slope of the roof
has influenced all types of metal construction
referred to patented systems for greenhouse
where they do not impede the passage of
is the increased quality of the finishes.The
glazing with metal glazing bars and clips that
rainwater. Horizontal joints have been sup-
quality of powder coating has improved
secured the glass quickly and reliably.The
ported with stepped joints where water
enormously, with greater durability and
term patent glazing is still used but these are
running off the top of the upper glass down
colour-fastness, so that it competes strongly
now usually thermally broken and hold dou-
onto a lower glass.The glass is traditionally
with the more expensive PVDF finishes. Con-
ble glazed units.The outer seals are able to
secured with clips and is sealed with a pro-
sequently, the main constraint in the design of
remain watertight at much higher wind pres-
prietary sealant.This joint is difficult to seal
metal roofs in any of these systems is that
sures from wind driven rain, and are drained
reliably in order to achieve water tightness
metal sheet is produced in widths of around
and internally ventilated in the manner of
for higher wind pressures, and is difficult to
1200mm or 1500mm, but is usually available
facade systems. Rainwater penetration of
adapt to a drained and ventilated system.
in long lengths where coil material is used,
joints in glazing systems has long been asso-
This issue has been resolved over the past
that is, where the metal is rolled into a long
ciated with a pressure difference between
20 years with the development of silicone
coil in the factory. Most metal panels in
the external air and the air pressure inside
bonded glazing that was originally used in
facades are made from coil material, where a
the glazing system if it is completely sealed. A
glazed curtain walls. In the new method, a
similar constraint applies in material width.
lower pressure inside the system than out-
metal channel is set along the top and bot-
Thicker plate, at 4mm thickness and above, is
side drew water in through joints which
tom of double glazed units, with the units
made in flat sheet form, at around 1000mm
resulted in leaks through both glazed roofs
being set flush with one another along the
x 2000mm in size, with larger sheets being
and glazed walls.This issue has long been
horizontal joints.The units are then secured
more difficult to obtain easily in large quanti-
resolved by draining away any water that
with metal clips within the depth of the joint
ty.Working with the width of the coil in
passes through the outer seals in drainage
to provide a mechanical restraint.The hori-
forming joints, and allowing for the folding or
grooves set adjacent to the edges of the
zontal joint between units is then sealed
turning of the material at the joints, is the
double glazed units, beneath the pressure
with silicone.The aluminium frame onto
main constraint, but the material can be
plate that holds the glass in place.Water is
which the glass is fixed has ventilated
curved and folded economically to achieve
drained at the bottom, where air is allowed
drainage channels to take away any water
almost any form required, in a durable mater-
to enter into the area in which the drainage
that passes through the outer silicone seal.
ial, with finishes that will retain their crisp
chamber is located to ensure there is no
With the development of silicone bonding
appearance up to around 25 years.
pressure difference between inside and out-
techniques in recent years, the double glazed
side.
unit can also be bonded to aluminium pro-
A change over the past 10 years which
Although drained and ventilated systems
MCR_ 10
files which are mechanically fixed with
Mercedes Benz Design Center, Stuttgart, Germany. Architect: Renzo Piano Building Workshop
Like a twin wall facade, this roof design incorporates both glazing and solar shading.The use of internal shading allows daylight to be directed within the space, allowing daylight to be reflected off the internal shading to adjust the quality of daylight.
screws to a supporting frame.The joint
glass forming a continuous rooflight with the
held in a perimeter frame that supports the
between the glass units is then sealed with
supporting structure and solar shading,
cables in the form of a ring beam.Where the
silicone in the same way as the previous
where required, set outside the glass.Where
rooflight is surrounded by an opaque roof,
example. An alternative approach has been
a rooflight is seen mainly from outside, and
where it forms an opening in a concrete
to introduce horizontal glazing bars with
the structure is set on the inside, the
roof deck for example, the ring beam is not
pressure plates that are shaped to allow as
rooflight is seen in terms of its volume,
visible, but where it forms a complete roof,
much water to drain down the roof as possi-
almost as a solid block of glass without visi-
the resulting perimeter structure can be
ble, and accepts that the same water will be
ble structure.The preference for the uninter-
visually dominant, so this approach is highly
trapped behind the upper edge of the pres-
rupted plane of glass with a certain reflectivi-
dependent upon the visual elegance of the
sure plate.This small amount of rainwater
ty is developing alongside the preference for
perimeter structure when this structure is
will evaporate, and any small amounts of
transparency in rooflight design.Where bolt
exposed. Bolt fixed rooflights are moving
water that find their way through the outer
fixed glazing for rooflights was preferred
away gradually from a dependence on the
seal will be drained away within the system.
originally for its greater transparency as a
X-shaped cast bracket, which is very charac-
Both the recessed fixing method with a sili-
result of its frameless, point fixed, design, this
teristic of the technique used to date,
cone seal, and the modified pressure plate
method is now being used more for the
towards more flat plates and welded brack-
system have been proved very reliable in
uninterrupted planes and modelled forms of
ets, which are both more economic and
their performance.
glass it creates.This is seen in the technical
ensure more visual emphasis on planes or
development of the systems, where the bolt
forms created by the glass than on the fixing
applied more slowly to new roof designs
fixing supports only one side of the double
system of brackets and bolts.
than its use in facades.The technical success
glazed unit, with the outer sheet of the dou-
Bonded glass rooflights are a recent
of bolt fixed glazing is in part dependent on
ble glazed unit having no bolt fixing penetra-
development in glazed roofs, where double
high levels of workmanship on site to form
tion, and consequently no visible fixings on
glazed units are bonded directly onto a light-
the joints between glazed units.This led to
the external face of the glass.This takes bolt
weight metal frame that has no visible fixings
some difficulties in the early application of
fixed glazing a step further towards a glazing
on its external face. But where bolt fixed
bolt fixed glazing in roofs but this has been
system with no visible fixings.
glazing can conceal the fixing bolt within the
Bolt fixed glazing for rooflights has been
subsequently solved. An advantage of bolt
The use of bolt fixed glazing to provide
double glazed unit on one side, structural sil-
fixed glazing over framed systems is their
greater visual transparency has led to an
icone glazing has no visible structure at all,
ability to be fixed from either inside or out-
increased use of cable net supporting struc-
with supporting glazing bars being concealed
side.Where framing glazing has the support-
tures. Cable nets for bolt fixed glazing com-
within the width of the joint behind the
ing extrusions on the inside, even if the glaz-
prise cables, usually in a rectilinear grid of
external seal.This has led to greater freedom
ing bar extends to the outside of the roof,
stainless steel cables where bolt fixings are
in the forms used for rooflights in this tech-
the grid of metal framing remains visible.
set at the intersection points of the cables.
nique, where the position of the glazing bars,
With bolt fixed glazing the rooflight is seen
The effect of these structures is like a tennis
and how they intersect, does not have to be
increasingly as an uninterrupted plane of
racquet, where visually lightweight cables are
considered in rooflight design.The conical-
MCR_ 11
An overview of roof systems International Port Terminal,Yokohama, Japan. Architect: Foreign Office Architects.
The innovative use of a folded steel plate structure allowed the roof structure to be completely visible within the building, while providing an innovative topography of the external roofscape.
shape rooflight described in Chapter 2 has a
movement from either the building structure
appearance similar to that of fabric 'tent'
painted top which is shown formed in metal,
or from solar gain when exposed to the
membranes.This change from roof mem-
but could also be made in cast glass.There is
effects of the sun. A solution to this problem
branes which are kept concealed due to
an absence of glazing bars and cappings
has been the 'inverted' roof configuration,
their poor visual aspect are now capable of
(which require relatively simple, or large
where thermal insulation is fixed above,
being an active part of the visual design.
radiused forms in order to fix them) are not
rather than below, the waterproof mem-
Some manufacturers offer upstand angles in
required in this glazing system, so that very
brane in order to keep its temperature cool
the same material as the membrane, typically
sculptured forms can be made, where the
and relatively constant. Pebbles or paving
for PVC membranes, which can be used to
glass dominates rather than any visible grid of
slabs are set onto the insulation. But asphalt
direct rainwater across the roof in the same
framing members, capping pieces or a close
is still required to span movement joints and
way as standing seam metal roofing.This
arrangement of bolt fixings that would be
interface with other materials.The introduc-
development also allows joints between
required with other glazing methods. Bonded
tion of polymers into asphalt to provide this
membrane pieces to be joined with standing
glazing has encouraged the use of structural
greater flexibility has led to the material
seam joints in order to visually refine the laps
glass beams, which suit well a structurally
being easier to apply on site, particularly as
between strips of membrane. Roof mem-
glazed rooflights. Most bonded glass
torch-on membrane sheet rather than in liq-
branes are set to become visible finishes in
rooflights with a gently sloping, but planar
uid applied form. However, polymer materi-
their own right rather than being concealed,
surface are derived in part from examples of
als, mainly thermoplastics and elastomers, are
which will no doubt lead to more refined
glass floor decks and staircases used in build-
becoming more economic. Polymer materi-
roof edges, where a parapet wall will not be
ings that have been developed over the past
als have the advantage of increasingly being
required to conceal the roof behind, allowing
15 years.The increased use of glass beams is
able to be exposed to sunlight, which is lead-
balustrades to be used at roof edges rather
set to continue with the greater reliability
ing to roofs being covered in a few of these
than using a parapet as a visual barrier to
and understanding of the behaviour of glass
materials as a self-finish, with some buildings
conceal the exposed roof membrane.
beams when accidental damage occurs.This
taking the membrane down the facades to
technique may well find a development in
form a complete building envelope.Where a
mer-based membranes, or polymer modified
translucent plastics rather than in the contin-
smooth or level substrate can be formed,
asphalt sheet, is beginning to be used as a
ued use of glass alone.
with foam-applied thermal insulation or with
material in its own right rather than imitating
a board-material finish with thermal insula-
the appearance of traditional roof tiles or
tion beneath, these waterproofing layers,
shingles.The more refined fixing techniques
which can also be used on metal and timber
that are being made available by manufactur-
branes for concrete roofs over the past 25
roof decks, can be formed in the same way
ers will assist in this change.Waterproof
years have focused on increasing the flexibili-
as fabric membranes, which are welded
membranes are increasingly being used on
ty of the material used. Asphalt, a well estab-
together in the factory to form a membrane
unusual substrates such as folded steel sheet
lished material for concrete decks, suffered
with straight and crisply formed joints that
decks and foam insulation-clad roof decks
traditionally from an inability to take up
can form a visible self finish to a roof, with an
where there is a strong modelling of the
Concrete Developments in waterproofing mem-
MCR_ 12
On pitched roofs, visually exposed poly-
Tram Station, Strasbourg, France. Architect: Zaha Hadid Architects.
This folded concrete deck provides a roof canopy that has a strong visual form that is not visually weakened by the typical demands of waterproofing and rainwater drainage.
roof structure seen either from inside or
have become more complex, with electroni-
roofs of this type is in trying to retain the
from outside the building. Membranes are
cally controlled valves that irrigate roofs to
appearance of traditional roofs, where venti-
required to accommodate more structural
suit the vegetation for different times of year.
lation ducts and boiler flues did not, until recently, play a part. Modern tiled, slated and
movement and higher temperatures combined with an external wearing surface that
Timber
shingled roofs use two lines of defence
can be walked upon without reasonable risk
Timber-based roofs have developed
against rainwater penetration, where the
of damage, for maintenance access.The use
over the past 20 years to improve their ther-
outer layer is the outer line of defence to,
of membranes, both visible and concealed
mal insulation performance. Most techniques
and protection for, a waterproof membrane
are set to develop along these lines over the
of tiles and slates are based on long tradi-
or breather membrane beneath. As require-
next 10 years.
tion, but not with the high levels of thermal
ments for thermal insulation increase in
insulation required in recent years with the
order to reduce energy consumption within
past 20 years on more lightweight buildings
need to reduce energy consumption within
buildings, the requirements for the avoidance
rather than their more established applica-
buildings. Cold roofs, with the insulation set
of interstitial condensation within the roof
tion on concrete roof decks. A difficulty
at ceiling level with the roof void being venti-
construction will increase correspondingly. As
encountered with planted roofs has been
lated, continue to be used, but warm roofs
a result, roof forms will no doubt change, as
the weight of soil and drainage required to
have undergone much development in order
will the currently dominant requirement to
grow vegetation which increases the cost of
to properly deal with the needs of ventila-
imitate traditional lapped construction.The
the building structure. Over the past 20
tion to avoid condensation occurring within
increasing use of photovoltaic panels as a
years, thin planted roofs have evolved that
the roof construction. Some manufacturers
substitute for tiles in certain areas of a
require only 50mm of growing medium to
prefer to have no ventilation within the roof
pitched roof (which also imitate the appear-
produce a roof covered in low height vege-
construction where it cannot be easily pro-
ance of traditional tiles and slates) will proba-
tation.This, in part, is due to better designed
vided by using a high performance vapour
bly increase, as will the use of tiles as solar
drainage layers in polystyrene which hold a
barrier on the inside face of the wall con-
collectors for hot water systems in temper-
controlled amount of water, optimised for
struction immediately behind the internal fin-
ate climates.These will no doubt influence
the needs of the vegetation, so that the
ishes. In practice, this is difficult to always
the design of pitched roofs for dwellings in
weight of soil and water can be reduced to a
achieve, particularly around penetrations
the years to come.
minimum.This allows planted roofs to be
through the roof such as pipes and ventila-
Planted roofs have been in use for the
An interesting development in pitched
used on lightweight roofs in all materials.This
tion ducts. Manufacturers also provide
roofs has been the use of metal shingles.This
technique has been popular where the
increasingly higher performance vents to
technique is a hybrid of lapped tile roofing
external appearance of a roof is intended to
ensure that air can be drawn through the
and standing seam facades, and can be used
have the least visual impact on its surround-
void between the roof tiles, slates or shin-
to form both wall and roof in a single system
ings, mainly in semi-rural areas, without the
gles, and the breather membrane or roofing
that is both economic and able to deal with a
need for complex and expensive structure
felt that is set above the thermal insulation.
variety of fixing angles.Where shingles or tiles
to support the vegetation. Irrigation devices
Most of the effort in ventilating pitched
are hung from their top edge, metal shingles
MCR_ 13
An overview of roof systems Natural Ellipse,Tokyo, Japan. Architect: Masaki Endoh and Masahiro Ikeda.
The membrane covering of this building mixes the methods of concealed polymer membranes, which are usually concealed, with the language of both tensile structures and plastic-based forms.This innovative use of an economic material allows 3D forms to be created economically, and without the need for traditional roofing elements.
are folded over into a seam on their sides
30 years ago, ensuring that colour fading is far
where two-sided finishes are required, as is
and lower edge, or edges, if the shingles are
less pronounced than it was.This is partly due
the case with opaque rooflights where both
not rectilinear, but are set at 45° to the verti-
to the coatings used, which are often paint-
an internal decorative and an external weath-
cal, for example.The top edge or edges are
based finishes on opaque panels. A greater
erproof finish are required. Smaller scale
fixed with nails or screws with the shingle
acceptance of plastics as durable and capable
polymer-based components have yet to use
immediately above being lapped over the top
of being moulded economically to complex
injection moulding techniques due to any sig-
of the nailed fixing in the manner of tiling.
shape has undergone the beginnings of a
nificant amount due to the costs involved.
This fixing method secures the shingles on all
revival in roof design. Some panels have been
This may change over the next 10 years as
sides while retaining a visual lap, allowing the
used as translucent rainscreen panels with
machinery costs reduce, particularly CNC
shingle to be fixed in any position, even in a
lighting or graphic displays set beneath the
milling and cutting machines which are well
soffit condition.The fixing method usually fol-
outer plastic skin.The essential difficulties for
adapted to working with plastics and com-
lows rainscreen principles by assuming that
plastics remains in their perception as being
posites. An essential difference between plas-
rainwater will pass through the joints, which
less durable than either glass or metal, for
tic-based materials and metals is that plastics
are drained in a ventilated cavity behind.
which polymer materials are seen as eco-
can be moulded to very large single forms
Metal shingles are economic to fabricate,
nomic substitutes.This perception will change
without the joints required in sheet-based
since they can be cut easily from sheet metal,
only when more complex geometries of
metal.Where metal roofs require cover strips
from aluminium, mild steel, copper or zinc. In
external enveloped are demonstrated in
and flashings at interfaces to deal with junc-
addition, tiles can be formed to a curved
buildings which could not otherwise have the
tions between components, this is not
shape in a press to give a very textured
budget available for such work in other mate-
required in plastics.The complexity of detail-
facade with a 3-dimensional quality that has
rials.Working with plastics and composites is
ing in metals gives a certain visual richness
yet to be explored in this technique.
still undertaken in relatively small-scale work-
that is not present in plastic-based materials
shops, where mock-ups can be produced
that imitate similar forms, but new forms of
easily and economically, allowing an interac-
double curves, twin layer construction of high
tion between designer and fabricator that is
levels of thermal insulation, and integrated
to imitate the appearance of glass rooflights
more difficult in larger scale factory-based
rooflight and electrical lighting installations
as flat sheet materials, and as composite pan-
methods where repeatability of large num-
can give plastics a language all of their own.
els.This is gradually changing as plastics are
bers of identical components still dominates
Examples of the moulding ability and flexibili-
no longer seen as economic substitutes for
production methods.
ty of the material is seen in consumer prod-
Plastics Translucent plastics are used mainly both
other materials but as construction materials
Glass reinforced polyester (GRP) is a
ucts and vehicles, and the possibilities are
in their own right. Earlier examples of plastic
material that is growing in popularity but is
beginning to find their way into building con-
rooflights suffered from the effects of colour
restricted to having only a finished surface on
struction.
fading or of yellowing in transparent / translu-
one side only as a result of using single-face
cent rooflights.The materials and finishes
moulds. Moulded items are bonded together
used in bonding are superior to those used
back to back where components or panels
MCR_ 14
Fabrics The use of woven textiles made from
Bus Station, Lugano, Switzerland. Architect: Mario Botta.
The use of polycarbonate panels provides a visually lightweight canopy that appears to float above the surrounding space. The crisp assembly, expressed as separate roof elements, gives the roof an elegant, durable quality.
polymers is relatively new to building con-
The large scale nature of most membrane
formed from a mixture of transparent and
struction and its use has been focused on its
roofs also makes cleaning difficult.The intro-
translucent panels.These panels are inflated,
application to create tent-like roof forms.
duction of double layer membrane roofs will
fixed to a permanent air supply that periodi-
Tension structures that imitate the geometry
no doubt change their use from purely
cally refreshes the cushions with more air to
of traditional tents from around the world
weather barrier to a thermally insulated roof,
maintain the pressure required to give them
have developed from early examples of
making them more attractive for roofs to
structural stability.The use of fabric is set to
canopies of 35 years ago.Tent-based struc-
internal spaces than shelters for sports stadi-
grow, with air cushions that can be used in
tures stretch a single membrane sheet, which
ums and semi-open courtyards in buildings.
conjunction with external solar shading or
is waterproofed on its external face, over a
More translucent insulation materials reduce
internal screen walls in a variety of twin roof
supporting structure that may use a mast to
the amount of light transmission lost through
or twin wall applications. Like sheet plastic
support the tent, and cables to hold the
these roofs, with research being undertaken
materials, ETFE cushions are just beginning to
membrane in position, in the imitation of a
to form an economic and highly translucent
be liberated from the design language of glass
traditional tent.This has led to some interest-
thermal insulation material that would suit
rooflights, with more complex geometries to
ing developments in the connection of mem-
double layer membranes. An alternative
form curved roofs. Loadbearing air cushions,
brane to cable and restraint of cables to
method of insulating membranes is to fill the
which do not require any supporting struc-
adjoining structure. Alternatively, membranes
gap in a double layer membrane roof with air
ture, are in their early stages of development
are stretched over more sculptured support-
to form an inflatable roof.The concern with
and application, and we are likely to see
ing frames, which are derived more from the
this approach is that it relies on a constant
much of this development in roof structures
established language of building construction
supply of air to hold the roof in place rather
and self-supporting envelope structures in
than from the masts and cables of tent-based
than by a supporting frame which does not
the coming years.
roofs.The design life of these roofs is gradual-
rely on electrical machinery to retain its
ly increasing as both a result of observing
structural integrity. Although inflatable struc-
by the width in which they are manufactured,
earlier examples and developing them, as
tures are used in temporary or seasonal roof
though ETFE/glass fibre sheet is much wider
well as an improvement in the performance
enclosures, this method has been adapted as
than the PVC/polyester type.The joints in the
of the protective coatings applied. Most coat-
small 'cushions' or 'pillows' filled with air to
membrane, similar to those used in polymer
ings aim to reduce surface friction as low as
provide an insulated fabric membrane roof.
membranes on roof decks in concrete, metal
possible to reduce the amount of dust and
The most visually striking examples use ETFE
and timber, could see a convergence of tech-
dirt that accumulates on roofs, so that it is
foil which is both very durable when com-
nologies, with waterproofing membranes,
cleaned efficiently by natural rainfall rather
pared to other polymer fabrics, and also high-
glass sheet and plastic sheet finding a com-
than relying exclusively on washing the mem-
ly transparent.While this can be a disadvan-
bined language in a single roof rather than
branes by hand in regular cleaning mainte-
tage in rooflights where some amount of
being entirely different solutions for a single
nance.This is usually successful, bearing in
solar shading is usually required, it is ideal for
roof design.The combining of these tech-
mind that most fabric roofs are difficult to
many facades and is finding use in complete
nologies in less rectilinear-based roof designs
access on a regular basis for washing by hand.
building envelopes, where wall and roof is
could lead to ever new roofing techniques.
Fabric membranes are currently limited
MCR_ 15
Working with manufacturers, fabricators and installers Atelier and House, Biwa-cho, Shiga Prefecture, Japan. Architect: Shuhei Endo Architect Institute.
This building uses a roof structure which is continuous with the external walls to create a single 'wrap' for the envelope. While this design approach has been used on larger-scale projects, its use in smallscale buildings is innovative.
As roof design approaches the visual com-
mation.Where the roof design varies little
porting structure and glazing, particularly in
plexity of facades, the amount of detailed
from these standard systems, little additional
providing structural loading information
design, mock-ups and testing is increasing
information is needed in order to proceed to
which can could be incorporated into the
towards that of facades, particularly where
tender with a drawn solution that will suit a
overall structural design for the building.
the roof is either large in relation to the size
range of manufacturers whose systems could
of the envelope, or where the roof forms a
be used. If the proposed system is fundamen-
with proprietary membranes, require little
visual continuity with the facades beneath.
tally different from established systems, then
consultation with manufacturers before ten-
Concrete roofs, which are usually sealed
one or two manufacturers are usually invited
der, with movement joints and typical junc-
a mixture of manufacturers' proprietary
at an early stage to see whether they would
tions being detailed in a similar way by a
components or systems, fabricators assem-
like to develop the system further before
range of manufacturers.The exception is in
blies and installers' work on site in fixing
tender, leading to negotiations for the con-
planted roofs, where soil depth, or the rela-
these items. Most roofs are based on manu-
tract at a point when it becomes clear which
tively thin depth of an equivalent growing
facturers' systems, except on smaller pro-
manufacturer or fabricator can undertake the
medium, and its attendant loads, need to be
jects, where traditional techniques are still
project within the budget allowed.This is par-
established at an early stage in order to allow
used.Traditional techniques are largely
ticularly important in the case of mixed sys-
for a minimum of two or three different pro-
absorbed into manufacturers' proprietary
tems, rainscreens, or double layered roofs,
prietary planted roof systems to be used. Flat
systems, which focus on reliability, economy
where there are fewer precedents, and
concrete roof decks require close coordina-
and ever increasing amounts of thermal insu-
where detailed design and testing is required
tion with the rainwater drainage system to
lation, while overcoming condensation prob-
to ensure their long term performance as
ensure that they can be accommodated, par-
lems associated with these developments.
part of the completed building.
ticularly where drainage outlets are closely
Roofs and roof coverings are installed in
Roofs made primarily from metal, con-
Glazed roofs usually follow the standards
coordinated with the facades or with the
crete and timber are, for the design team,
of glazed curtain walling, and are well defined
ceiling layout below.The increased use of 2-
primarily manufacturer/installer based, while
in their range of details. However, the design
way rainwater outlets at the edge of roofs,
glass, plastic and fabrics are manufacturer/fab-
team will need to consult manufacturers at
rather than visible outlets in accessible roof
ricator based. Having established the general
an early stage if an outer layer of solar shad-
decks, makes this requirement for coordina-
appearance of a roof, the design team pro-
ing is required, for example, as penetrations
tion more acute.
ceeds to the detailed design in a variety of
through framing members and through joints
ways depending on the material used.
(in the case of bolt fixed glazing) are less
systems, with even metal shingle roofs being
Timber roofs usually use well established
commonly used in rooflights. Some large cur-
provided as tested systems.They are usually
tems, made by manufacturers with the
tain walling companies have branched into
capable of being fully designed by the design
exception of rainscreen panels and canopies,
specialised roof structures that can provide
team prior to tender, since the techniques
which are usually undertaken by fabricators.
advice, at an early stage, for unusual designs.
involved are well known. Lapped tiles, slates
Standing seam, profiled metal and composite
Companies that fabricate unusual glazed
and shingles are undergoing constant devel-
panel systems are made by manufacturers
roofs, who are based in steel fabrication, can
opment in the building industry, and the lat-
who can be approached at an early stage of
also provide useful information at an early
est improvements will be offered by installers
the project to request general technical infor-
stage about the relationship between sup-
during the tender stage.The choice of specif-
Metal roofs are mostly proprietary sys-
MCR_ 16
Saltwater Pavilion, Neeltje Jans, Holland. Architect: Oosterhuis Associates
The external membrane uses a spray-applied polymer-based coating which mixes the visual language of asphalt and liquid-applied roofing membranes with the technology of polymers to create an innovative appearance that is set to develop in the coming years.
ic tile or slate or shingle is usually made at
brane, can be made at an early stage in con-
closely linked to the design team. It is impor-
early stage of the project, with approximate
sultation with fabricators. Once the material
tant to visit their facilities at an early stage of
costs being provided by manufacturers for
and budget have been matched, a specialist
the project to establish their capability both
the supply of the materials at an early stage.
structural engineer can proceed with an ini-
in terms of complexity and scale as well as
Contractors, or installers, usually bid to install
tial design, where supporting structure can
their experience in previous projects.
a system which is already specified by the
be developed in parallel with the fabric
design team. Asphalt-based materials are
membranes.
already well developed and can be detailed
In general, working with manufacturers of
Installers, particularly if they are also general building contractors, can provide information at an early stage about the suitability
with confidence by the design team ready for
roof systems is not as flexible as with facade
of a design for ease of construction as well as
tender.
systems, but this situation is quickly changing
associated costs of bringing materials to site.
with the development of new systems in
If a suitable method can be agreed for bring-
tems, with smaller manufacturers offering
most materials. As roofs move increasingly
ing certain materials to site and lifting them
individually designed systems which are a
towards the visual complexity and technical
onto the roof easily, for example, then more
mixture of panels and specially formed com-
performance of facades, manufacturers are
ambitious designs can be realised within a
ponents, such as nosings and gutter sections.
making themselves more available to develop
more modest budget.The amount of on site
Where plastic-based roofs are made as
their systems with architects and engineers.
installation and off-site fabrication can then
structural shells, they are usually designed for
The ability to negotiate costs for the supply
be optimised by the design team to achieve
each individual project and fabricated in the
of a system to site assists in this matter, with
the required design without adding significant
workshop.The design team usually ensures
the tender being restricted to the installation
time to the construction period on site.
that the design will suit two or three tender-
of a particular system which has been adapt-
ers, but a preferred contractor may be cho-
ed by the design team for a specific project.
the properties of each material, and the
sen at an early stage due to the specialist
A visit to the factory of the proposed system
working methods associated with each,
nature of the work. Negotiation of costs at
supplier helps the design team to understand
should be grasped from the outset, together
an early stage is advisable in plastics for this
both how components are made and the
with an idea of how the materials are trans-
reason.
constraints under which they are manufac-
ported to site and assembled as a complete
GRP roofs are made as proprietary sys-
Above all, an essential understanding of
tured. It also helps to see whether any part
roof.This can assist the contractor when
ion roofs can be designed by the design team
of the system which the design team would
entering discussions about the merits of the
with the assistance of structural engineers
like to modify can be accommodated with-
setting up a temporary workshop on or near
specialising in these tensile structures, which
out adding significant extra costs to the pro-
the site, as opposed to transporting assem-
allows the design to develop rapidly without
ject.
blies over long distances from a factory.
Fabric membrane roofs and ETFE cush-
involving specific manufacturers, who may be
Fabricators are becoming more ambi-
When the design team better understands
reluctant to produce a detailed geometry
tious both technically and in terms of visual
the materials with which they are working,
and determine the forces that would be
quality offered, mainly in metals, glazing, plas-
the quality of construction is enhanced as a
applied to the supporting structure.The
tics and fabric membranes.They are usually
result.
choice of material, and hence the width of
able to respond at an early stage of a project,
material available to form a seamed mem-
and if appointed early on, become more
MCR_ 17
Performance testing of roofs The testing of a roof system is undertaken typically with a small test panel that contains the full range of joints that comprise the system as well as the maximum span that the system can accommodate. This is to ensure that adequate weatherproofing can be provided while the system experiences maximum deflections from both positive and negative wind pressures.
Testing of water tightness of mock-ups has
problems inherent in the system, particularly
beneath to provide as air tight an enclosure
until recently been restricted mainly to
if some innovation is involved, and allowing
as possible. A door is provided into the
facades. Roof structures are usually tested in
the design team to see how the roof will
chamber which is able to be clamped shut
a specialist laboratory when they differ tech-
appear before proceeding with the work in
during the testing.
nically from standard systems, or have an
the workshop or on site.The mock-up can
unusual combination of standard systems.
also be used to establish an accepted level of
air supply in order to establish the amount of
Testing is usually restricted to systems in
quality of construction, particularly with
air infiltration through the system.The air
metal, glass and plastics. Concrete, timber and
regard to visual crispness of assembly, flatness
supply is provided usually by a flexible hose
fabric do not usually require test mock-ups,
of materials, visible joint widths, finishes and
that passes through an opening in the ply-
since their performance is well established
colour.
wood chamber enclosure.The hose is con-
The test chamber is pressurised with an
nected to a centrifugal fan which can either
both in the systems used, and as industry-
The workshop usually has at least one
wide specifications.Test rigs determine the
panel or set of joints that covers an area suf-
supply air to, or extract air from, the test
ability of the mock-up to remain watertight
ficiently large to provide full structural deflec-
chamber.
and airtight when the various design loads
tions of framing members, as well as internal
are applied to the mock-up. In addition, the
ventilation and drainage in the case of glazed
testing is an aero engine with propellers
effect of a falling object onto the roof is test-
roofs.There is little point in testing a panel
which acts as a generator for the wind pres-
ed when it is considered essential to with-
300mm x 300mm in size that includes only
sures applied to the test mock-up. A grid of
stand the load to protect building users
one joint, since the overall effects of move-
water spray nozzles is set above the mock-up
beneath when they are at possible risk, from
ment under full design wind load cannot be
in order to simulate rainfall onto the roof.
higher buildings adjacent to the roof, for
determined unless a full panel is tested.The
A canvas bag filled with small diameter
example. A test that is particular to roofs, and
test mock-up panel is set at the same angle
glass spheres is provided for the soft body
is not undertaken in facades, is the flood test.
at which it is to be used in the completed
impact test, which is typically dropped from a
An area of roof is filled with water up to a
installation.Where a range of angles are
mobile platform or temporary scaffolding
level anticipated in the event of rainwater
encountered, the most vulnerable, or
tower set next to the test sample.
outlets being blocked and left standing for up
extreme, angles are taken to form the mock-
to several days.This is usually undertaken on
up.The roof mock-up is set 1500mm to
flat roofs where there would be standing
2000mm above the ground level to allow the
In order to establish the rate at which air
water in the event of blocked outlets, and
underside to be inspected easily, and set typi-
filtrates through the assembly, the mock-up is
applies to pitched roofs only at gutters or
cally on a concrete slab.The roof sample is
first subjected to a single positive pressure
drainage points.This test is usually undertak-
usually supported on a steel frame at its
'pulse' which is held for 10 seconds, which
en on site, typically for single membrane
edges in a way that simulates the structure
corresponds to half of the design pressure
roofs on a flat roof deck in either concrete,
used in the building.The space beneath the
for the roof system.This is done in order to
steel or timber.
roof is then enclosed, usually with plywood
pressurise the test chamber and ensure that
sheets which are sealed at the interfaces with
the chamber has been properly sealed.This is
the mock-up and with the floor slab or deck
done before testing commences.The pres-
Mock-ups for performance testing have the added benefit of revealing the installation
MCR_ 18
The largest external component in the
Air infiltration test
The test chamber, which is capable of being fully sealed, is fitted with an air supply to provide both positive and negative air pressures on the internal face of the roof sample panel.
sure inside the chamber is now increased to
visible as a result of penetrating the roof
repeated at 1.5 times the design wind pres-
a difference of 600 Pascals between inside
assembly.
sure in a safety test.The pressure is then increased to a maximum of 2.0 times design
and outside.The roof sample is first sealed with tape to determine chamber leakage, and measurements of airflow are taken, which, for
Wind resistance tests In these tests, pressure transducers are
wind pressure to examine what would happen in the event of failure if this limit is not
fixed rooflights should not, typically, exceed
fixed to the inside face of the roof sample, in
reached.Typically, failure occurs in a seal in
1.1 m3 per hour per m2.The airflow test is
positions where the deflectors are most criti-
the roof assembly, or a glass panel may break
repeated with the tape removed.The differ-
cal, such as at the centre of framing mem-
in a rooflight, but this occurs usually when
ence between the two readings indicates the
bers, or the centre of panels.Transducers are
the 2.0 times design wind pressure is exceed-
air infiltration rate through the roof sample.
telescopic gauges that measure deflections,
ed.
usually to an accuracy of 0.25mm. Readings
Water penetration tests
are taken digitally at a distance from the test
These tests are conducted both under
chamber.The transducers are set by applying
Impact resistance test The ability of a lightweight roof, typically a
static air pressure, that is, with no significant
a positive pressure 'pulse' of 50% of the posi-
glazed or plastic-based rooflight, to withstand
wind blowing across the sample, and at
tive wind pressure for 10 seconds. After a
an object falling on it is simulated with a can-
dynamic air pressure, where an aero engine
recovery period of up to 5 minutes, the pres-
vas bag 400mm in diameter, filled with the
blows air onto the sample. In the first test,
sure transducers are set to zero to establish
glass balls already described, to a mass of
the static air pressure water penetration test,
a 'zero' level for the test. A positive pressure
around 50kg.The bag is dropped from a
water is sprayed from nozzles onto the roof
is then applied to the roof mock-up and held
height of around 750mm to simulate an
mock-up at a rate of at least 3.4 litres/ m
for 10 seconds at different pressure deflec-
impact energy of around 350 Nm in a safety
/minute.The water spray nozzles are set out
tions. Readings are taken at 50%, 75% and
test.The test is performed on joints and pan-
on a grid so that nozzles are no more than
100% of the positive design wind pressure.
els to establish that the complete roof
700mm apart, and are fixed at around
After a period of up to 5 minutes, any
assembly would not fail under these impact
400mm from the face of the sample.This
remaining (or permanent deflections) in the
energies.
ensures that all parts of the roof sample are
sample are recorded.This process is repeated
sprayed with water. A pressure differential
for negative wind pressure, where air is
corresponding to 600 Pascals is applied
drawn out of the test chamber.The test
across the sample for 15 minutes.The interi-
starts again from the beginning, with a 50%
mock-up is dismantled to ensure that the
or face of the mock-up is checked for any
pulse held for 10 seconds in order to estab-
mock-up was built exactly in the way it
water penetration.The test is repeated at the
lish a 'zero' level for the transducers.
would be applied on the roof of the finished
2
same pressure with a propeller-type aero
These two sets of tests for positive and
Dismantling of sample When the tests are complete, the roof
building. In the event of a test failure, this dis-
engine to provide the same 600 Pascal pres-
negative wind pressures establish whether
mantle assists the design team to understand
sure difference across the sample.The under-
the mock-up deflects within the limits set out
how to resolve the matter, and prepare the
side of the mock-up, inside the chamber, is
in the design, at the design wind pressure
mock-up for a second round of testing if
checked to ensure that no water drops are
(typically 1400 Pascals).These two tests are
required.
MCR_ 19
Roof-mounted maintenance systems : Davits and monorails Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
1 10 10
5
9 2
4
5 3
Section 1:25. Davit supporting cradle in two positions.
MCR_ 20
Davit Roof finishes Facade Solar shading panels Cradle Monorail Bracket supporting monorail Beam supporting monorail Safety line for harness Cable
1
1
1
3
5
4
5
Plan 1:25. Davit supporting cradle in two positions.
With the increased use of metal, glass and
facades (discussed In Modern Construction
is usually hung on cables from a davit at each
composite materials in facade design there
Facades) are often provided in the form of
end of the cradle. Davits are moveable and
has been a greater requirement for cleaning
walkways set at each floor level. Most sys-
when in use are secured to bases in fixed
and maintenance. Building facades 30 years
tems, however, are roof-mounted and are
positions near the roof edge. Davits are very
ago were detailed with low levels of mainte-
required to be integrated into the roof
useful for roofs where the permanent visual
nance envisaged, with the use of brick, con-
design, usually with a minimum of visible
presence of a monorail or trolley system is
crete, stone and timber dominating architec-
equipment.These roof-mounted types are
not the preferred solution to facade mainte-
tural design. Facades would be cleaned only
discussed here. Most facades are cleaned
nance.
rarely, with details that would weather well
with either davits, monorails or trolley sys-
with the passage of time.Windows in mason-
tems mounted at roof level, with larger
aluminium tube and are moved with wheels
ry walls were detailed to be openable, partly
buildings having a mixture of these systems
at their base.This makes them sufficiently
to admit fresh air for ventilation and partly
on a single roof.
lightweight and mobile to be handled by one
for cleaning access.With the increased use of sealed facades without openable windows came an increased requirement for cleaning equipment. Facade cleaning systems for twin wall
Davits are usually made of mild steel or
or two people when they are moved into
Davit systems A davit is a jib or scaffold-shaped frame
position and fixed for use. Davits are usually dropped into position onto a set of bolts
from which a cleaning cradle is hung. A single
projecting up from the roof surface, typically
cleaning cradle, holding one or two persons,
as either plinths in the form of short
MCR_ 21
Roof-mounted maintenance systems : Davits and monorails
6
Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
Davit Roof finishes Facade Solar shading panels Cradle Monorail Bracket supporting monorail Beam supporting monorail Safety line for harness Cable
5
5
5
Section 1:25. Monorail supporting cradle from balcony.
Example B
Plan and section 1:25.Typical cleaning cradle.
columns, or as a recessed box below the
cradle is fitted with an electric winding
moved to its next position by descending to
level of the roof finishes where the bolts are
mechanism and rubber fenders to avoid
its lowest level and disconnecting the cables.
concealed from view, as on an accessible
direct contact with the facade.There is no
The davits are then unbolted and lowered
roof terrace.The davit is lifted into position,
winding mechanism at the level of the davit;
from their bases before being moved to the
usually by a person pulling it up with a rope
whose function is to support the cables only.
adjacent base positions for re-connection.
secured to the top of the post.The arm of
The electrical power supply for the cradle
the davit can be swung outward once it is
motors is from points either at roof level or
involving erecting davits, setting up the cables
fixed in place. Cables, secured to the end of
at the base of the facade, supplied to the
and cradle, then disconnecting the parts and
the davit arm before it is lifted into position,
cradle by a power cable. In the event of a
moving the davits again, this method avoids a
are lowered down the facade to be attached
power supply failure, a manual system in the
permanent and visible cleaning system being
to the cleaning cradle below, at the base of
winch allows the cradles to be lowered to
mounted on the roof.The davit system is
the facade.The cradles usually have wheels
the ground.Various proprietary systems of
most commonly used where the roof is
which enable them to be moved to suit each
winch motors and lifting equipment are
used as an accessible roof terrace, or garden,
new pick-up position for the davits as they
available, all with different safety features.
where a permanent cleaning system would
are moved to each new fixing point on the
When one vertical strip of facade is
roof.The cables are connected to the cradle,
cleaned by a cradle that is raised and low-
allowing it to be raised up the facade.The
ered from a pair of davits, the cradle is
MCR_ 22
While this is a relatively slow process
not be visually desirable.
7
6
10
5
3 4
5
Elevations 1:25.Typical cleaning cradle.
Monorails In the monorail system, a continuous single rail is fixed at roof level, from which a cleaning cradle is hung from a cable at each end.The monorail is set around 500mm beyond the edge of the roof to allow the cradle to hang slightly forward of the facade, typically on brackets cantilevered from the roof structure as shown in (A).The monorail is a visually strong element that is integrated into the overall design for the edge of the roof. An alternative to cantilevered fixing brackets is to cantilever the edge of the roof out by around 500mm as shown in (B).The rail is usually made from mild steel which is
Section 1:25. Monorail supporting cradle from beam.
painted or enclosed in a decorative metal cover, usually in folded aluminium sheet.
MCR_ 23
Roof-mounted maintenance systems : Davits and monorails
2
7
6
9
10
5
2
3
Section 1:40. Cleaning with harness on platform.
Where cantilevered support arms are used
rail.When manually operated, the cradle can
these can be castings or standard structural
be moved when at the bottom of the facade
steel sections to suit the design.The mono-
if maintenance personnel are assisting at
rail, set horizontally, is usually formed as a
roof level.The monorail offers a visually dis-
channel-shaped section that allows a pair of
creet method of providing a permanently
wheels to run inside the rail. Sets of wheels
fixed cleaning system at roof level.
are operated either by sliding the cleaning
Where the monorail is hung from the
cradle beneath manually, or under electrical
underside of a balcony or slab soffit, the
power for larger installations. As with the
monorail can be concealed with cladding
davit system, cables are connected from
panels set on either side of the rail. From
wheeled pulleys which travel inside the
below, only a single continuous groove is visi-
monorail.The cables are lowered down and
ble. A gap of around 20mm is provided
connected to the cleaning cradle, which is
between the monorail and the adjacent
set at the bottom of the facade. As each ver-
panel to allow for movement of the mono-
tical strip of facade is cleaned, the cradle is
rail itself when in use.This joint is either left
moved along the facade, usually when it is at
open or closed with a flexible seal, typically
roof level, just below the level of the mono-
EPDM sheet.
MCR_ 24
Section 1:50. Monorail supporting cradle from cantilevered brackets. Example A
1
2
1
1
2
3
5 3
Plan 1:25. Davits supporting cradle.
Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
Davit Roof finishes Facade Solar shading panels Cradle Monorail Bracket supporting monorail Beam supporting monorail Safety line for harness Cable
10
5
1
3
Section 1:25. Davits supporting cradle.
Section 1:50. Davits supporting cradle.
MCR_ 25
Roof-mounted maintenance systems :Trolley systems
9 1
9
1
5 8
5
Elevation 1:100.Trolley supporting cradle.
8
Section 1:50.Trolley on vertically-set rails.
5
1
1
5
8
1
8
Elevation 1:100.Trolleys supporting cradle.
MCR_ 26
5
Details 1. 2. 3. 4. 5. 6. 7. 8. 9.
1 5
Trolley Roof finishes Facade Solar shading panels Cradle Monorail Horizontal rail supporting cradle Vertical rail supporting cradle Cable
1 1
5 3
9
5 1
Section 1:250.Trolleys on vertically-set rails.
Example D
1
3
9
1
1
5
5
5 3
3
Section 1:250.Trolley on vertically-set rails.
Trolley systems
The arms are sometimes telescopic
trolley itself. As the trolley is controlled
Where a facade is required to be cleaned
(hydraulically operated) in order to reach
remotely, safety at roof level is a critical con-
from a roof which is either sloping, or has a
either the facade or, for example, solar shad-
sideration.Where roofs are required to be
stepped profile in elevation, a horizontal
ing panels in front of the facade.The arms
accessible, rails are mounted above the roof,
monorail is a much less practical solution for
are usually raised or lowered to bring the
but their dominant appearance may deter
supporting cleaning cradles. Davits are usually
cradle in and out from the facade and to
this solution in practice.Where the trolley
difficult to handle on sloping roofs.Trolley sys-
bring it to rest at roof level.The trolley itself
can be seen from below, it is usually con-
tems are better adapted to reaching facades
houses the motors for moving the equip-
cealed behind a screen or in a small enclo-
from a sloping roof and where the facade
ment along its rails, moving the arms, and
sure, allowing it to be protected from the
itself is of complex geometry.Trolleys are typ-
raising and lowering the cradle itself.The
effects of the weather.Trolley systems are
ically mounted on wheels and are secured to
trolley is usually controlled from within the
well suited to being mounted on sloping or
a continuous track, which may be beneath
cradle, allowing it to move both vertically
curved roofs where they climb steep slopes,
the trolley, as roof-mounted rails, as (C), or
and horizontally.
typically up to around 45°.
may be set vertically as (D).The trolley usual-
This system is not usually suited to roofs
Where facades step in at a lower level,
ly has arms which project out over the edge
which are fully accessible to building users
the cradle can be offset from its supporting
of the roof which support a cleaning cradle
due to the presence of rails, or a dedicated
cables by the use of counterweights attached
from cables fixed to the ends of the arms.
path, as well as the visual presence of the
to the cleaning cradle.The cradle can be
MCR_ 27
Roof-mounted maintenance systems :Trolley systems Details 1. 2. 3. 4. 5. 6. 7. 8. 9.
5
Trolley Roof finishes Facade Solar shading panels Cradle Monorail Horizontal rail supporting cradle Vertical rail supporting cradle Cable
1 2
3
7
Elevation 1:100.Trolley with reach over adjacent facades.
Example C
moved by an arm fixed directly to the sup-
behind a parapet formed by solar control
porting cables. As the arm moves from a
louvres. It is set on a track that forms a con-
vertical position to the horizontal, the cradle
tinuous loop to suit the shape of the build-
swings away from its cable.The movement is
ing. As the trolley moves around its circuit it
balanced by a counterweight at the other
is able to reach all parts of the facade.The
end of the arm which keeps the cradle level
trolley is able to reach the facades with tele-
and stable.This method is useful in facades
scopic arms that can be adjusted both in
which either step outwards as rise up or are
length and height to suit the facade being
inclined outwards through their height.The
cleaned. A single trolley is usually provided
mixture of a trolley system and cradles
for a single building, but more than one may
allows complex facade and roof forms to be
be required, working on the same track, to
cleaned and maintained from a single clean-
suit different facade geometries beneath.
ing cradle.With facade and roofs of complex
Not all large-scale trolleys require tracks to
geometry, the trolley rails can be concealed
restrain them.Trolleys with wheels, that
in a gutter at roof level where facade and
move on a raised portion of roof deck, are
roof form a single and continuous form.
also used.
In the example above a trolley is set
MCR_ 28
2
1
2
3
3
Elevation 1: 250.Trolley with reach over adjacent facades..
1
9
7 2
3
5
Elevation 1: 100.Trolley with reach over adjacent facades.
MCR_ 29
Roof-mounted maintenance systems :Trolley systems
5
6
9
6 9 9
5 5
Section 1:25. Cradle hanging from trolley.
6
5 9
5
9
5
5
Section 1:25. Cradles hanging from monorail.
MCR_ 30
Section 1:100. Cradles hanging from trolley and monorail.
Details 1. 2. 3. 4. 5. 6. 7. 8. 9.
Trolley Roof finishes Facade Solar shading panels Cradle Monorail Horizontal rail supporting cradle Vertical rail supporting cradle Cable
5 1
8
1 5
8
Section 1:100.Trolleys on vertically-set rails.
5
5
5
Plan 1:25. Cradles hanging from trolley.
MCR_ 31
1 METAL (1) Metal standing seam Site-based method Prefabricated methods Sealed and ventilated roofs Roof openings Ridges and valleys Eaves and parapets (2) Profiled metal sheet Profiled metal decks as substrates Profiled metal roof sheeting Sealed and ventilated methods Twin skin construction Ridges Openings Eaves and parapets Ridges and valleys (3) Composite panels Single wall composite panels Twin wall panels Ridges Verges Eaves Parapets and valley gutters (4) Rainscreens Panel arrangement Parapets Monopitch ridges and verges Roof geometry Roof soffits (5) Metal canopies Bolt fixed panels Fixed metal louvre canopies Electrically operated louvres
MCR_ 33
Metal 01 Metal standing seam
1
Long section1:10. Typical roof assembly with acoustic layer
6 1
3 11
2
3
4
4
11
2
5
Isometric view of roof assembly Museum, Arnheim, Holland. Architect: Mecanoo architekten
Cross section1:10.Typical roof assembly with acoustic layer
1
3
4 2
Standing seam roofs are increasingly being
The traditional method of forming a
make the use of prefabrication both unnec-
used for industrial and commercial buildings
standing seam roof is to set the sheet onto a
essary and uneconomic, due to the time
in preference to profiled metal sheet where
timber substrate, and to fold the long edges
needed to make special junctions and edges
concealed fixings and low roof pitches are
of the metal upwards to form a standing
on site.The use of a single sheet metal pro-
required for visual reasons.This is because
seam joint. However, this method is increas-
file and angle support clips used in prefabri-
standing seam roofing is both economic and
ingly giving way to prefabricated systems
cated methods is usually too inflexible for
has crisp, uninterrupted joint lines that allow
where the sheet metal is folded to a specific
such conditions.
it to be made a visible part of the building
profile either in a factory or on site with a
design, often with as much architectural
rolling machine.The folded metal is then
standing seam roofs, timber boards or ply-
presence as the facade beneath.The main
secured with a clip-based fixing system
wood sheet is used to form a continuous
advantage of standing seam roofs over pro-
rather than onto a continuous substrate.
substrate, or supporting surface. Standing
filed metal roofs is that almost no fixings pass
Both types are discussed in this section.
seams are formed by timber strips of recti-
through from outside to inside the construction.This gives the roof surface a visually crisp appearance with very few visible fix-
In this traditional method of forming
linear or curved section which are set at
Site-based method This method of fixing sheet is well suited
450-600mm centres down the slope of the roof, corresponding to the width of the
ings.The standing seams allow the technique
to small-scale applications, or where com-
sheet metal used. Sheet metal is laid along
to be used on very low pitch roofs.
plex geometries are used.These applications
the length of the roof from top to bottom,
MCR_ 34
Section 1:10. Eaves with curved gutter 11 1
3
4
7 5
12
13
Details 1. 2. 3. 4. 5. 6. 7. 8. 9.
10
Outer standing seam sheet Inner lining sheet Fibre quilt thermal insulation Vapour barrier Purlin or structural beam Secondary purlin Folded metal gutter Folded metal drip Metal fascia panel
10. 11. 12. 13. 14. 15. 16. 17. 18.
External wall Outer sheet fixing bracket Curved eaves sheet Structural frame Ridge piece Metal flashing Rooflight Pipe or duct penetration Parapet flashing
1 1
3
3
3
4 4 2
2
Cross section1:10. Typical roof assembly without acoustic layer
Long section1:10. Typical roof assembly without acoustic layer
with the sides of the sheet folded up and
lated joint, a small gap is left between the
400-600mm centres. Profiled metal sheet is
over the timber battens. Successive strips of
folded sheets to allow air to pass through
increasingly being used as a substrate, as it
metal sheet are lapped over the next to form
but not rainwater.
provides a self-finished soffit (underside) to
a continuous sealed surface.The standing
Sheet metal is fixed to the timber
the space below the roof.This is particularly
seam joint is formed by folding the metal
upstand strips either by clips, which avoid
useful where acoustic ceilings are used, with
together to form a seal. Because the roof is
penetration of the sheet metal, or by a
perforated sheet that has a paint coating on
formed, effectively, as a series of linked 'gut-
mechanical fixing through one side of the
its underside.
ters', the standing seam between each gutter
sheet.The fixing is applied to the side which
is above the level of the water draining down
has the adjacent sheet lapped over it, in
it. Rainwater is avoided being drawn through
order to avoid rainwater passing through the
the joint by capillary action by one of two
fixing penetration.Timber-based substrates
fabricated standing seam roofs is a structural
methods, where the joint is either sealed or
are increasingly being replaced by profiled
deck, typically reinforced concrete or pro-
ventilated. In a sealed joint the seam is
metal sheet, which has a much greater span-
filed metal sheet, with insulation set on top
pressed tight, as in a traditional lead or cop-
ning capability than plywood sheet, helping
and an outer (upper) sheet supported on
per roof either by folding the metal over
to reduce the cost of the supporting struc-
brackets set onto the structural deck. An
itself to form a thin seam, or by forming the
ture.Timber-based substrates, typically ply-
alternative configuration is to fix the brackets
metal over a timber roll or section. In a venti-
wood or timber boards, require support at
supporting the outer sheet to a set of metal
Prefabricated methods The most common configuration of pre-
MCR_ 35
Metal 01 Metal standing seam 15
1 1 16 11
11 3
7
3 1
4 2
4
3
10
2 10
4 5
2 5
Section 1:10. Eaves with exposed gutter
Section 1:10. Junction with rooflight
Section 1:10. Monopitch ridge
Details
Section 1:10. Folded eaves
1. 2. 3. 4. 5. 6. 7. 8. 9.
1
3
11
Outer standing seam sheet Inner lining sheet Fibre quilt thermal insulation Vapour barrier Purlin or structural beam Secondary purlin Folded metal gutter Folded metal drip Metal fascia panel
10. 11. 12. 13. 14. 15. 16. 17. 18.
External wall Outer sheet fixing bracket Curved eaves sheet Structural frame Ridge piece Metal flashing Rooflight Pipe or duct penetration Parapet flashing
Section 1:10. Roof penetration 4 1
2
5 17 11
3
10 4 2
13
5
purlins. A metal liner sheet is set below the
arrangements for road transportation in
joints are crimped to form a seal, usually
purlins to support thermal insulation quilt, set
most countries. For larger projects, long
with a 'zip up' tool that travels along the
between the purlins. A vapour barrier is set
sheets are formed on site with a rolling
joint and across the roof, sealing the joint as
between the insulation quilt and the liner tray
machine that can form the profile of the
it moves along.This fixing method gives very
on the warm (in winter) side of the thermal
standing seam sheet to any length required,
smooth and straight joints, but the long
insulation. In hot, humid countries an addi-
the profile being formed from metal coil.
lengths of sheet metal forming the roof sur-
tional vapour barrier is set on top of the
Support brackets are usually T-shaped
face can result in 'oil canning', where part of
insulation where the risk of interstitial con-
and are fixed either to the structural deck or
the metal surface appears to be crinkled as a
densation is from the outside as well as the
to purlins with self-tapping screws.The
result of uneven thermal expansion. Gener-
inside.
brackets are usually made from extruded
ally, thermal expansion is accommodated by
aluminium in order to provide a profile that
allowing the long lengths of metal sheet to
roof pitch can go down to 1°, after taking
is both thick enough to form a rigid connec-
slide over the support clips, with the sheet
into account any structural deflections that
tion and sufficiently precise in section to
itself fixed rigidly in only a few places along
would further reduce this angle. Metal sheets
retain a given standing seam profile in place.
its length.
can be made up to 40 metres in length, but
Metal sheet is formed in long lengths of fold-
road transport is difficult, with long sheets
ed trays which are then fixed onto the sup-
curves by gently bending the metal on site,
(longer than a trailer length) requiring special
port brackets. Finally the standing seam
or alternatively by curving the sheets in the
For both construction configurations the
MCR_ 36
Standing seam sheets can form shallow
1
15 1
18 11 3
3 4 7
4 2 13
10 2
10
Section 1:10.Verge
Section 1:10. Concealed eaves gutter
Section 1:10. Parapet gutter at abutment
Section 1:10. Parapet gutter at abutment
10 10 1
1 15
7 11 3
7
3
4
4
2
2 5 5
factory, to give a smooth appearance. Small
geometry.This allows the thermal insulation
traditionally been provided with open joint-
radius curves are formed by crimping the
to be set horizontally beneath, while the
ed timber boards, but this method is being
sheet in the factory, where the material is
roof form can be free of the constraints of
replaced on larger applications by a plastic-
mechanically formed with small local folds.
making the entire roof construction follow
based woven mat set onto a substrate,
Sharp folded corners are made by welding
the same geometry.Ventilated roofs have
which allows air to pass across the inside
two sheets together along the fold line.
slots at ridges, valleys and perimeter gutters
face of the zinc while using a continuous
to allow air to pass through the construction
substrate material beneath.
Sealed and ventilated roofs The choice of a sealed or ventilated roof
to ensure that the roof build-up remains dry. Sealed roofs use sealing strips in the standing
Roof openings
configuration depends upon both the metal
seam joints to make them both airtight and
Rooflights are set into standing seam
used and the nature of the construction
watertight. Moisture vapour that builds up
roofs in one of two ways: either by forming a
beneath.Ventilation is essential if the thermal
inside the construction is released by slots
pressed metal upstand around the opening
insulation is set some distance below the
for passive ventilation at the ridge and eaves.
so that the rooflight projects up around
metal sheet, as in a pitched roof where the
Unlike other metals, zinc sheet requires
150mm above the level of the roof, or by
insulation is set horizontally, above a closed
ventilation on the underside to avoid corro-
setting it level with the roof finish and form-
ceiling.Ventilated roofs are also suitable
sion from water vapour trapped inside the
ing a gutter around the edges of the
where the external roof form has a complex
construction.Ventilation for zinc roofs has
rooflight.This second method avoids the
MCR_ 37
Metal 01 Metal standing seam Details 1. 2. 3. 4. 5. 6. 7. 8. 9.
Outer standing seam sheet Inner lining sheet Fibre quilt thermal insulation Vapour barrier Purlin or structural beam Secondary purlin Folded metal gutter Folded metal drip Metal fascia panel
10. 11. 12. 13. 14. 15. 16. 17. 18.
External wall Outer sheet fixing bracket Curved eaves sheet Structural frame Ridge piece Metal flashing Rooflight Pipe or duct penetration Parapet flashing
Section 1:10. Curved ridge
Museum, Arnheim, Holland. Architect: Mecanoo architekten 1
12
4
Section 1:10. Abutment with masonry wall 10
3
8
5 2
15 1
3
13
2
need for rooflights to appear as projecting
ing is bonded to the metal sheet roof cover-
terminated to avoid the need for visually
box-like forms in an otherwise smooth, con-
ing and sealed, typically with a silicone-based
bulky filler pieces being seen from below. In
tinuous roof plane. If the rooflights are set
bond and seal. Standing seams that clash
(C) the ridge is treated as a soft fold, with-
into the opening, then a metal flashing is fixed
with the base of the skirt flashing are
out any break in the material. Although this
around its edge, being lapped under the
stopped and closed above and below the
may appear to be the most straightforward
standing seam roof on its top edge. At the
penetration.
of the ridges to form, the alignment of the
sides the flashing forms a standing seam with the adjacent joints running down the roof, and its bottom edge lapped over the top of
ridge piece is as critical as in versions (A)
Ridges and valleys
and (B) in order to create a straight ridge
Ridges are formed by a variety of meth-
line. Shadows from the sun cast across the
the roof sheet immediately below it. Penetra-
ods. In (A) a folded or curved metal sheet is
ridge will reveal any waviness in the line of
tions for small ducts and pipes through the
set over the gap between the two sides of
the top of the roof.
standing seam roofs use simplified flashings.
the roof on the level of the top of the stand-
An upstand is formed as a continuous skirt
ing seam.The gap between the top and bot-
of the standing seam roof into a folded
around the projecting pipe and a flashing,
tom of the standing seam is closed with a
metal tray forming a continuous gutter.The
usually welded to the pipe, folds over the top
formed metal filler piece, or strip. In (B) a
gutter is often welded at the joint between
of the upstand to avoid rainwater from pene-
sharp ridge line is formed as a standing seam
one length of folded sheet and the adjacent
trating the joint.The base of the 'skirt' flash-
joint, with the seams meeting the ridge being
sheet in order to avoid the possibility of a
MCR_ 38
Valleys are formed by lapping the ends
14 15
1 1 3 3
4 2
2
5
5
5
Section 1:10. Ridge with flashing
Section 1:10. Expansion joint
Detail A
Section 1:10. Ridge with recessed flashing
Detail B
Section 1:10. Abutment with masonry wall
1 14
10
3
8
4 2
Section 1:10. Curved ridge
15
Detail C 1
14
1
3
3
4
4 2
2 5
water leak in the gutter. Because of the reduced roof depth at gutters, thermal insu-
Eaves and parapets
to the top of the external wall. A parapet
Eaves are formed in a similar way to a
coping is set into this seal as an overcloak
lation set below it is often thinner than the
valley, with a gutter set at the edge of the
flashing and second line of defence against
adjacent areas of roof.The reduced thermal
roof. Increasingly, gutters are being integrated
rainwater penetration.
insulation can be improved upon by using
into roof forms in order to avoid a weak
either higher performance insulation in that
visual line formed by a gutter which is not
area, or by deepening the structure of the
continuous with the smooth lines of the
roof beneath where this is possible, to allow
roof.When additional closer pieces are used,
the depth of thermal insulation to be
such as bull nose profiles, the metal panels
increased.
are usually designed to be drained and venti-
If the roof is ventilated, the gap formed
lated to the exterior, and the line of water-
between the top of the gutter upstand and
proofing continues up the external wall to
the underside of the standing seam roofing
the underside of the standing seam roof.
allows the passage of air into the roof void
Parapets are formed by taking the side
without the need for ventilation slots, visible
of the gutter that is adjacent to the external
from below, being set into the outer face of
wall up to the parapet coping, where it is
the roof.
terminated with a rubber-based seal bonded
MCR_ 39
Metal 02 Profiled metal sheet
1
3
4
6
5
Isometric view of roof assembly
Details
Long section and cross section1:10.Typical roof assembly
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19.
1 1
3
3
4
4
6 6
5
Outer profiled metal sheet Inner lining sheet Fibre quilt thermal insulation Vapour barrier Purlin or structural beam Profiled metal structural deck Folded metal gutter Folded metal drip Metal fascia panel External wall Outer sheet fixing bracket Curved eaves sheet Structural frame Ridge piece Metal flashing Rooflight Pipe or duct penetration Parapet flashing Vented filler piece
The main advantage of profiled metal sheet
has an advantage where the interior finish is
The deep sections are also used in compos-
over other metal roof types is the ability of
designed to be in a different material, such as
ite roof decks when filled with concrete. For
the material to span economically up to
dry lining or decorative boarding. In recent
a steel profile, sheets of 0.7mm thick are
around 3.5 metres between primary struc-
years roof pitches have greatly reduced to
used for the outer skin; for aluminium a
tural supports.This self-supporting ability of
make the roof as flat as possible, usually for
0.9mm thick sheet is used. Steel is galvanised
the material, combined with its weather resis-
visual reasons. Most profiled sheet is laid to a
and coated, while aluminium is mill finished
tant, painted coating applied during manufac-
minimum pitch of around 4°. Standing seam
or coated.
ture, makes it able to be used as both a sub-
roofs can go down to a 1° pitch, depending
strate material for a finish in a different mate-
on the geometry of the roof.
rial set onto it, or as a single layer structural
When used as a substrate, profiled metal
Profiled metal decks as substrates Where profiled metal is used as a deck
and weatherproof material.Where standing
sheet can be cut to form complex geome-
rather than as a roofing material, a light-
seam roofing, with its high projecting folds, is
tries, typically supported by a steel frame to
weight build-up is usually applied, since the
suited to long, straight, or gently curving
create a 3-dimensional form. Profiled sheet
metal decking is chosen where a lightweight
spans, profiled metal sheet can both span
with an overall depth of 50mm is used typi-
roof is required.The lightweight finishes used
between supports and form complex
cally, but much deeper sections are used for
are typically an additional layer of profiled
geometries. It is this flexibility of being both
spans above 3.5 metres to around 6.0
sheet, metal standing seam (discussed in the
structural deck and waterproofing layer that
metres, with a depth up to around 200mm.
previous section), membranes (mainly elas-
MCR_ 40
1 8
4
2
12 7
3
2
13
Section 1:10. Duct/pipe penetration 10
Section 1:10. Curved eaves with concealed gutter Atelier and House, Biwa-cho, Shiga Prefecture, Japan. Architect: Shuhei Endo Architect Institute
17 1
3
2
tomers) and light planted roofs. A typical
insulation which would otherwise cause its
curved easily, where the supporting struc-
build-up is of closed cell insulation set onto
deterioration.
ture beneath requires only a few structural
the profiled metal deck, rigid enough to span across the peaks of the profile without
members to be curved, and most framing
Profiled metal roof sheeting
can be straight. Used as roof sheeting, the
deflecting significantly when it is walked upon
When used as a finish material, called
material is lapped on all four sides like metal
for maintenance access, which would other-
'roof sheeting', profiled metal sheet provides
standing seam roofs.The laps are made long
wise stretch the joints in the membrane. A
a continuous weatherproof skin with the
enough to avoid capillary action through the
single layer membrane is then set onto this
ability to be curved in one direction. A limi-
joint.This simple jointing system provides
insulation, usually an elastomeric membrane
tation of the material is that openings for
large areas of reliable, weathertight roofing
that can be left exposed to the effects of the
rooflights, edges, and junctions with other
that can be installed quickly.
sun without damage. Sometimes a thin layer
materials are not easily integrated into the
of smooth pebbles is laid on top to keep the
profile of the sheet. Even simple rectilinear
sun off the membrane and allow mainte-
openings have few standard profiles to close
nance access without risk of puncturing the
off the gap between the flat flashing and the
profiled metal roofs can be used as a roof
membrane.The closed cells of the material
gaps between the peak and trough of the
covering in either sealed or ventilated con-
ensures that any water vapour trapped in
profile. However, one of the main advantages
struction.Ventilation is used mainly where a
the construction is not absorbed by the
of profiled metal sheet is its ability to be
timber supporting structure is used, where
Sealed and ventilated methods In common with standing seam roofing,
MCR_ 41
Metal 02 Profiled metal sheet 10
1
1
15
5
8
3
3
7
5 4
4 13
13
Section 1:10. Folded metal valley gutter
Section 1:10. Abutment with masonry wall
Section 1:10. Prefabricated valley gutter 1
3
3
11
11
Details
1
19
2
2
5
Detail A
5
13
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19.
Outer profiled metal sheet Inner lining sheet Fibre quilt thermal insulation Vapour barrier Purlin or structural beam Profiled metal structural deck Folded metal gutter Folded metal drip Metal fascia panel External wall Outer sheet fixing bracket Curved eaves sheet Structural frame Ridge piece Metal flashing Rooflight Pipe or duct penetration Parapet flashing Vented filler piece
the timber is ventilated to avoid rot in the
tion. Sound is allowed to be absorbed partly
typically 1.5mm thick, with nylon washers or
material from moist air in the void that
by the insulation quilt.This helps to reduce
sleeves between the purlins and the outer
would otherwise be trapped within the con-
reverberation, particularly in noisy internal
and inner sheets to provide a thermal break
struction.This is discussed further in the sec-
environments. A vapour barrier is set
as well as a pad to seal the screw fixings on
tion on timber pitched roofs.The following
between the thermal insulation and the thin
the outer roof sheet. In recent years the Z-
topics in this section deal with the use of
layer of acoustic insulation beneath.
shape section has developed into to a wide
profiled sheet as a sealed roof covering. In sealed roofs, the thermal insulation usually fills the voids in between the inner
range of section types. Sheets are fixed with
Twin skin construction Profiled metal sheet roofs have the abili-
self tapping screws which, in addition to fixing the sheets to the supporting structure,
and outer skins, but ventilators are often pro-
ty to conceal the supporting structure within
are also required to be weathertight. A
vided at the ridge and eaves to allow some
the depth of the roof construction.This gives
vapour barrier is provided on the warm (in
breathing through the ribs of the profiled
a smooth finished appearance to the inside
winter) side of the insulation, between the
sheet.This helps to keep the insulation com-
face of the roof. An outer metal sheet is sup-
liner tray and the thermal insulation.
pletely dry.
ported on metal roof purlins, and an inner
Because the inner lining sheet presents a
This construction method contrasts with
lining tray, which supports the thermal insula-
composite panels, where the outer skin, min-
hard surface under the roof, perforated
tion, is fixed to their underside.The purlins
eral fibre thermal insulation quilt and inner
sheets are used to improve sound absorp-
are usually Z-shaped galvanised steel types,
lining are combined into a single panel which
MCR_ 42
1
14 1 3 2
11
2
7
5 3
5
10
3
13 13
3
10
Section 1:10. Monopitch ridge
Section 1:10. Eaves with exposed gutter
Section 1:10. Folded eaves
Section 1:10. Abutment with vertical roof panel
10
3 5
1
11 3
1
4
2
10
11 5
4
3
3 2
5
11
13
13
is fixed onto a supporting structure which
surfaces together. Sheets are normally lapped
beneath the profiled sheet. Closer strips are
remains visible.The supporting roof struc-
150mm over one another, while laps
used to seal the gaps in the profiled sheet
ture, visible from below the roof, is either left
between sheets on their side edges are
where it meets the ridge cover strip set on
exposed on its underside or is concealed
made with a single lap of profile, with a sin-
top of the profiled sheet.
with a layer of dry lining.
gle seal of butyl tape set at the centre of the
Where a pitched roof meets an abut-
Laps between profiled sheets along their
lap. In common with standing seam roofs,
ment with an adjacent wall as in (A), the
top and bottom edges are sealed with butyl
the thermal insulation quilt is usually 150-
cover strip between wall and roof is folded
sealant strip.Two strips are normally used,
200mm thick in order to achieve a U-value
up the wall and is fixed to it. A flashing pro-
one at the end of the external lap and the
of 0.25 W/m2K.
jecting from the wall is lapped over the out-
other at the top end of the internal lap.The outer seal provides protection against capillary action of rainwater being drawn up into
side of the ridge strip in order to direct rain-
Ridges
water over it and down onto the roof.
Ridges at the junction of a double
Openings
the lap between sheets, while the other pro-
pitched roof use a folded metal strip to form
vides a vapour barrier that avoids moisture,
a continuous ridge sheet.These sheets can
generated inside the building, from condens-
be folded on a straight line or formed to a
standing seam roofing, a gutter is required
ing in the joint. Self tapping screws that hold
curved line.The void beneath is filled with
along the top edge of rooflights, along which
the sheets in place clamp the two sealed
thermal insulation in addition to that used
water running down the roof is directed to
In common with rooflights fixed into
MCR_ 43
Metal 02 Profiled metal sheet 16
1 1 4
2
5
4 3
2 3 7
13
13 10
Section 1:10. Eaves with semi concealed gutter Section 1:10. Rooflight formed with upstand
Section 1:10. Rooflight formed as profiled sheet Section 1:10.Verge
Details 1. 2. 3.
1
3
5 2
2 4
5
3
4
2
13
4. 5. 6.
15
1
13
10
7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19.
Outer profiled metal sheet Inner lining sheet Fibre quilt thermal insulation Vapour barrier Purlin or structural beam Profiled metal structural deck Folded metal gutter Folded metal drip Metal fascia panel External wall Outer sheet fixing bracket Curved eaves sheet Structural frame Ridge piece Metal flashing Rooflight Pipe or duct penetration Parapet flashing Vented filler piece
the sides.The gutter can be formed in front
counter flashing is welded or bonded to the
al, so that the parapet forms a visual break
of the metal sheet as in a parapet detail, or
upper part of the pipe, above the roof,
between them. However, many profiled
be concealed by setting the profiled sheet
which laps down over the flashing to protect
metal roofs are used in conjunction with
close to the rooflight and concealing the gut-
it from rainwater running down the pipe
walls in the same material using a concealed
ter, leaving only a 50mm gap between roof
above the roof level.
gutter that allows wall and roof to be contin-
sheet and rooflight.The gutter can be concealed for small rooflights since they carry little rainwater and so do not need to be very
uous. Manufacturers provide standard
Eaves and parapets Parapets are formed by creating a gutter
curved pieces to different radii in profiled metal sheet that allows the same material to
big.The sides of rooflights parallel to the
at the base of the profiled sheet, then con-
form a gently curved edge or, alternatively, a
slope, and along the bottom edge, have flash-
tinuing the line of the gutter up to a parapet
sharply curved termination to the roof
ings lapped down from the rooflights and
coping with laps over the top.The gutter is
which can be lapped into the profiled sheet
onto the adjacent roof sheets.
formed from a single folded sheet to avoid
forming the wall beneath. Eaves pieces with
Penetrations for small ducts and pipes
the possibility of leaks, and is lapped under
sharp edges are also manufactured as part
through the roof are sealed with a flashing,
the vertical sheet that forms the seal
of proprietary systems.These are formed to
usually welded to form a single upstand collar
between gutter and coping. Parapets in pro-
different angles by welding two profiled
around the pipe and fixed to the roof deck.
filed metal sheet are often used where the
sheets together to form a continuous
Also in common with standing seam roofs, a
external wall is formed in a different materi-
smooth fold in the roof. Curved pieces are
MCR_ 44
14 14 1 1 3 3 4 5
4 2
5
13
Section 1:10. Ridge with flashing
Section 1:10. Ridge with flashing
Section 1:10. Parapet gutter
18 1
Atelier and House, Biwa-cho, Shiga Prefecture, Japan. Architect: Shuhei Endo Architect Institute
3
10 3 7
4 5
usually made by crimping the material along
filler piece, usually forming part of the manu-
the vertical edges of the profiled sheet, to
facturer's system.Ventilated roofs do not
give a characteristic appearance, but these
require this filler piece, with the resulting gap
pieces are increasingly being made with a
between the folded ridge sheet and the pro-
continuous smooth appearance.
filed sheet being usually sufficient to provide ventilation into the construction.
Ridges and valleys These folds in metal roofs are formed
Valleys are also formed in a similar way to that discussed in standing seam roofs,
using the same methods discussed in the
with a ventilation gap provided in the gap
previous section on standing seam roofs. But
between the gutter and the underside of the
where standing seams can be cut down to
roofing sheet.
form a flat ridge without a projecting ridge piece, this not possible in profiled sheet, and instead a folded ridge piece is fixed to the upper surface of the profiled sheet.The gaps between the ridges and troughs of the profiled sheet are filled with a proprietary metal
MCR_ 45
Metal 03 Composite panels Section1:10. Panels with rainscreen covering at step in roof 1
Details 1. 2. 3. 4. 5. 6. 7. 8.
2 3
3
5
1
Metal rainscreen panel Single layer membrane Composite panel Folded metal coping Purlin or structural beam Secondary purlin Folded metal gutter Folded metal drip
9. 10. 11. 12. 13. 14. 15. 16.
Metal fascia panel External wall Outer sheet fixing bracket Panel 1 Panel 2 Ridge piece Structural frame Pipe or duct penetration
2
Section 1:10. Pipe / duct penetration
15
1
1
2
16
3
5
2
3
5
There are two types of composite panel
membrane is then typically finished in rain-
This development of composite panel design
used for roofs: twin wall and single wall pan-
screen panels or smooth pebbles, depending
has yet to be commercially available in a
els.The first is a development of profiled
on the geometry and required appearance
technically reliable system.
metal sheet, where outer sheet, thermal insu-
of the roof.
lation and inner sheet are combined into a
A development in composite roof panel
Single wall composite panels
single panel.These are used in pitched roofs
construction which has been slow to appear
and have an appearance very similar to that
commercially is the truly interlocking panel
filed metal on the lower loadbearing face of
of profiled metal roofs.Their main advantage
with integral gutter, where the principles of
the panel which is bonded to a foam-based
over profiled metal roofs is the speed of
composite wall panels would be applied to
insulation that fills all the voids in the profiled
erection on site, but they are usually a little
roof panels, making for use in (nominally) flat
sheet, providing a smooth, flat upper surface.
more expensive than an equivalent profiled
roofs.These panels would have the smooth
The depth of the thermal insulation is deter-
metal sheet roof.The second composite roof
face and edges used in wall panels to pro-
mined by the U-value required, and manu-
panel type, single wall panels, consists of pro-
vide a construction that would be both eco-
facturers are often flexible in this regard.The
filed metal sheet bonded to a layer of foam
nomic and very elegant.The joints between
upper face of the panel is waterproofed with
type thermal insulation.The insulation is laid
panels would form gutters that would create
an independent membrane, typically an elas-
face up to receive a separate waterproofing
a connected grid of drainage channels that
tomeric type that requires no upstands or
layer, typically a single layer membrane.The
could form a crisp joint line between panels.
special joints between sheets. Panels are usu-
MCR_ 46
This panel type has a single sheet of pro-
1 2
3
5
Section 1:10.Typical panel to panel junction Section 1:10.Typical panel to panel junction
School of Decorative Arts, Limoges, France. Architect: Labfac / Finn Geipel, Nicholas Michelin
Section 1:10. Parapet edge
Detail A 4
2 3
1
2 3
5
5
ally set butted up to one another, with the gap between panels filled with foam-based
direct sunlight. At ridges and folds in the roof geometry,
tional length of membrane is then bonded to the top of the upstand and is mechanical-
thermal insulation. A separating layer is usual-
panels are joined in the same way, with the
ly fixed or bonded to the top of the adjacent
ly set between the waterproof membrane
gaps between panels filled typically with a
external wall, typically formed in composite
and the insulated panel to allow movement
foam insulation applied by injection on site.
wall panels or glazed curtain walling.This
to occur freely in both the membrane and
The membrane sheets are usually joined at
parapet flashing is then protected by a fold-
the composite panel substrate.The sheets of
the fold in the roof, and a strip of the same
ed metal coping set onto it as shown in (A).
waterproof membrane are bonded or torch
material is bonded along the joint to provide
welded together by lapping one sheet over
a weathertight seal.
the other, or by using bonding strips in the
At parapet gutters, an upstand is formed
Single faced composite roof panels are well adapted to complex roof forms, where a lightweight, well insulated roof can be pro-
same material that form part of the propri-
in the same insulation material as that used
vided without the need for complex junc-
etary system.The membrane is often pro-
in the composite panels, the upstand being
tions that would be needed with twin wall
tected with a lightweight covering of smooth
bonded to the composite panel beneath.
panels.The use of a separate waterproof
pebbles that can be walked upon for mainte-
The outer edge of the upstand is sealed and
membrane on a substrate that is easy to
nance access without puncturing the surface.
stiffened with a metal strip fixed to the
form into a smooth continuous surface
Metal rainscreen panels are also used to
underside of the composite roof panel or
allows junctions to be formed easily, particu-
protect the membrane from the effects of
the supporting structure beneath. An addi-
larly around roof penetrations such as duct
MCR_ 47
Metal 03 Composite panels 1
2 3
5
Section 1:10. Panel to panel junction at fold Section 1:10. Panels with rainscreen covering
1. 2. 3. 4. 5.
3
5
Section 1:10. Panel to panel junction
Details
6. 7. 8.
Metal rainscreen panel Single layer membrane Composite panel Folded metal coping Purlin or structural beam Secondary purlin Folded metal gutter Folded metal drip
9. Metal fascia panel 10. External wall 11. Outer sheet fixing bracket 12. Panel 1 13. Panel 2 14. Ridge piece 15. Structural frame 16. Pipe or duct penetration
13
12
5
Section 1:10. Folded metal gutter set between panels
1 2
3
3
5
openings and pipe penetrations, where waterproof membranes are well suited due
Twin wall panels This panel type, which combines the
one long side, as (C), which laps over the adjacent panel.This gives a continuous
to the ease with which they can be cut,
separate components of profiled metal sheet
ribbed appearance to the roof that is visually
formed and sealed on site. Gutters can be
has two joint types: a double seam with a
no different on its outside face to profiled
formed by using the rapid site assembly
cap on top in the manner of standing seam
metal roof cladding. Both methods have
method of setting lengths of composite panel
roofing, or a single lap of profile in the man-
lapped joints on their short edges, where an
together, while a membrane bonded to the
ner of profiled metal decking.With the first
uninsulated edge projects down to form a
upper surface gives a watertight finish. Com-
method, panels have raised edges on their
lap joint very similar to that used in profiled
posite panels forming a valley gutter or para-
long sides running down the slope.The
metal roofs.These horizontal joints are also
pet gutter are fixed rigidly to reduce the
raised edges are butted together and sealed
sealed with butyl tape to avoid capillary
amount of structural movement that would
with butyl tape, as (B). A metal capping is
action from rainwater outside, and to pre-
otherwise damage the membrane, which is
fixed over this joint to provide a weather-
vent the passage of water vapour into the
typically bonded to the base and edges of
tight seal which sheds water onto the panels
joint from inside the building.
the gutter in order to closely follow its shape.
either side of the joint.This method gives a distinct visual appearance of wider joints.The second method has an uninsulated rib of the outer sheet projecting from the panel on
MCR_ 48
14 3
3
5
5 7
15
15
10
Section 1:10. Eaves with exposed gutter
Detail D
Section 1:10. Ridge with flashing Section 1:10. Parapet gutter
Section 1:10. Abutment with vertical roof panel
3 3
4
3 5
5
10
Ridges Ridges for twin wall composite panels
ceal, so that precise positioning is essential to the overall visual appearance of the ridge.
15
Verges Verges between composite panels and
are formed by fixing a metal flashing over
The gap between the panels is filled with
the adjacent wall construction is formed
the junction between the panels.The flashing
thermal insulation on site, with either miner-
with a folded metal closer.Where composite
is profiled to match that of the panels onto
al fibre quilt or, more frequently, with the
panels form the wall construction, a folded
which it sits. Manufacturers often make these
same foam-based insulation used to manu-
metal strip is sealed to the top of the last
profiles as part of their proprietary system.
facture the panels. Insulation is injected into
'peak' on the roof panel and is then sealed
Alternatively, a flat ridge flashing is used
the gap to provide a U-value to match that
against the wall panel. Alternatively, a Z-sec-
which sits onto the top of the profiled upper
of the adjacent panels.
tion closer piece is fixed and sealed to pro-
sheet.The gaps are then closed with a pro-
The inner face of the panels forming the
filed sheet and the flashing is fixed to the hip
filed filler piece as used in profiled metal roof
ridge is sealed with a folded metal sheet, typ-
of the closer piece.Where glazed curtain
construction.The angle between the meeting
ically fixed to adjacent roof purlins and
walling is used, the metal flashing is glazed
panels is closed by adjusting the angle of the
sealed against the inner face of the compos-
into the top transom of the glazed wall. As
fold of the ridge flashing on site, or by folding
ite panel to provide a continuous vapour
with ridges, the gap between the roof panel
a flat flashing over the joint to give a smooth
barrier.This inner trim is made either flat or
and the wall construction is filled with ther-
curve across the ridge line.The ridge flashing
profiled to suit the composite panels used.
mal insulation, and a folded closer strip is
has visible fixings which are difficult to con-
applied to the internal face of the joint to
MCR_ 49
Metal 03 Composite panels
3 3
3
5 5
10
15 15
Section 1:10. Monopitch ridge
Section 1:10. Prefabricated valley gutter
Details 1. 2. 3. 4. 5. 6.
Metal rainscreen panel Single layer membrane Composite panel Folded metal coping Purlin or structural beam Secondary purlin
7. 8. 9. 10. 11. 12.
Folded metal gutter Folded metal drip Metal fascia panel External wall Outer sheet fixing bracket Panel 1
13. 14. 15. 16.
Panel 2 Ridge piece Structural frame Pipe or duct penetration
4
Section 1:10.Verge with parapet upstand 10 3
5
provide a vapour barrier between the insula-
panel in the same way as for the eaves
els 'peaks' and cantilevering out to support
tion and the inside of the building.
detail.The inner face of the joint is sealed
the top of the gutter. An essential advantage
with a folded metal closer strip to provide a
of the metal support arm on the roof is that
vapour barrier.
it does not require any penetration through
If the verge overhangs the external wall instead of meeting it directly, then the void created by the overhang can be either ventilated or sealed. If sealed, then the overhang-
the wall construction to the supporting
Eaves
structure, but can be fixed through to the
ing verge follows the same detailing princi-
These are formed in a similar way to
ples. If the eaves void is ventilated, then the
profiled metal panels, by lapping the edge
fixing to pass all the way through the wall
edge of the verge is sealed to the edge of
roof panel over a gutter.The gutter is closed
panel, thus reducing the risk of any rainwater
the roof, while the wall beneath is sealed to
against the underside of the composite
penetration through the building envelope.
the underside of the composite metal roof in
panel either by folding it outwards and seal-
order to provide a continuous weather seal
ing it, as in (D), or by folding the top edge
without any break in the thermal insulation.
inwards, up the underside of the panel.The
Verges that terminate in a parapet use a
roof panels which do not usually require a
Parapets and valley gutters Unlike eaves gutters, parapet gutters are
gutter is supported by either a bracket
thermally insulated, since they form part of
flashing that is set behind the vertical panel,
beneath the gutter that is fixed back to the
the external envelope.The gutter is usually
or onto it to avoid a thermal bridge, and is
primary structure, or by a metal support
prefabricated to form part of the overall
folded to be sealed onto the composite roof
arm set onto the top of the composite pan-
composite panel system. Since an advantage
MCR_ 50
14
3
School of Decorative Arts, Limoges, France. Architect: Labfac / Finn Geipel, Nicholas Michelin
Isometric view of roof assembly Section 1:10. Panel to panel junctions
Section 1:10.Verge
Detail C
3
12
13
5
Detail D 10
15
12
13
of composite panel construction is the
prefabricated gutter being critical to avoid
thermal insulation to avoid a thermal bridge
increased speed of construction on site over
water penetration in the event of the valley
occurring through the coping into the air
other metal roofing methods, this advantage
gutter being filled to capacity in the event of
space behind.
would be lost if the gutters took much
a blocked rainwater outlet.
longer to fix and the panels themselves.The
The tops of parapets are closed with a
gutter shape, in cross section, is formed to
pressed metal coping that is folded down
provide continuity in the thermal insulation
over the face of the external wall and the
from roof panel through to the adjacent
inside face of the parapet to provide a com-
parapet wall. Seals are provided to avoid any
plete weathertight seal.The top of the cop-
water from penetrating the seals and passing
ing is usually inclined towards the inside face
into the building, which might occur in the
of the wall (into the gutter) to avoid dust,
event that the rainwater outlets become
that settles on horizontal surfaces, from
blocked and the entire gutter becomes filled
being washed down the face of the external
with water up to the level of the outer (top)
wall during rain.The coping is usually made
face of the composite roof panels.
from a minimum 0.7mm thick steel sheet or
Valley gutters are formed in a similar way, with the seal between roof panel and
3mm thick aluminium sheet.The void immediately beneath the coping is faced with
MCR_ 51
Metal 04 Rainscreens
1
2
Detail A 3
Detail B
4
5
Isometric view of roof assembly Section1:25.Typical cross section
3
1
2
4 5
The use of metal rainscreen panels is rela-
the backing wall, with a cavity between the
vide a lightweight covering that forms part of
tively new in roof construction, and has
thermal insulation and the inner face of the
the visual language of the external walls.
developed from its use in external walls. In
metal rainscreen panel, as shown in (A).
Although smooth pebbles are also used to
facades, rainscreen panels are used in a con-
In contrast, metal rainscreens for roofs
protect waterproofing membranes on roofs,
figuration that allows most of the windblown
vary considerably from the configuration
pebbles and gravel are obviously not suited
rain that reaches a metal panel facade to
used in external walls. Firstly, most of the rain
to sloping or curved roofs.The use of metal
drain down its face. Joints between metal
falling onto a metal rainscreen roof is not
rainscreen panels is well suited to these
panels are left open jointed, so that only a
usually drained away on the outer layer of
roofs which form a visible part of the design.
small amount of rainwater passes through it.
panels, unless the roof has a relatively steep
These panels allow traditional roof elements,
Rainwater is drained away in the cavity
pitch or curved section. Rainwater is still
which are usually visually dominant, such as
behind, the rear face of the cavity being
expected to drain onto the waterproofing
gutters, parapets and ridges, to be accom-
sealed, typically with a single layer membrane
layer beneath as if the panels were not in
modated within a smooth, continuous finish,
on an insulated, lightweight, backing wall. A
place.The main function of the rainscreen
allowing roofs to take on the visual charac-
commonly used alternative is of a bitumen-
panels on roofs is to protect the membrane
teristics of external walls and become a
based paint on a reinforced concrete or con-
from the effects of the sun (heat and UV
'facade' in their own right.
crete block backing wall. Closed cell thermal
radiation) as well as from the worst effects
insulation is usually set on the outside face of
of windblown rain. Rainscreen panels pro-
MCR_ 52
Although metal sheet is used, metal and plastic composites are becoming increasingly
Details 1.
1
2. 2
3. 3
4. 5.
4
6. 7. 8.
Metal rainscreen panel Single layer membrane Closed cell thermal insulation Structural deck Purlin or structural beam Secondary purlin Folded metal gutter Folded metal drip
Section 1:10. Panel to panel junction
Detail C Section1:25.Typical long section
1 2
3
4
Shimosuwa Municipal Museum, Lake Suwa, Japan. Architect:Toyo Ito & Associates
9. 10. 11. 12. 13. 14. 15. 16.
5
Metal fascia panel External wall Outer sheet fixing bracket Panel 1 Panel 2 Ridge piece Structural frame Pipe or duct penetration
Section 1:10. Panel to panel junction
1
3 2 4
popular, as they are less likely to become
1200mm wide, in lengths from 2400mm to
in the same plane in this configuration. Panels
dented from foot traffic during maintenance
3000mm, depending upon the manufacturer.
in a flat grid are set onto metal Z-sections,
work, which maintains the flatness associated
In practice, panels may only be around
which are either bonded to the top surface
with composite metal materials.The 'oil can-
600mm wide if they do not have additional
of the waterproof membrane to avoid any
ning' effect of depressed or dented panels,
supporting framing beneath to stiffen them.
risk of water penetration through mechani-
resulting from regular maintenance access is
Framed panels can reach the maximum sizes
cal fixings, or are set above the membrane
usually avoided by using these composite
already mentioned, but care must be taken
on support pads.These pads are usually cov-
sheet materials. In such materials a thin layer
to avoid the pattern staining or denting that
ered with a waterproofing membrane to
of plastic is faced with two thin sheets of alu-
can reveal the frame behind during the life-
reduce the number of fixing penetrations
minium which are bonded to the plastic
cycle of the roof.
through this layer.The rainscreen panels are
sheet core.The size of metal rainscreen panels is restricted more by the panel width that can be walked upon for maintenance access
then screw fixed to the Z-section with
Panel arrangement Rainscreen roof panels are typically
brackets that avoid the screw fixings being seen at a distance where this is a visual
than by the sheet size available.The maxi-
arranged either as panels laid in a flat grid, or
requirement. Unlike rainscreen panels for
mum size of metal sheet is usually in a width
as lapped panels, where the bottom edge is
walls, roof panels cannot be secured easily
of 1200mm or 1500mm metal coil. Com-
lapped over the top of the panel beneath.
on a hook-on type support system while
posite sheets are typically 1000mm to
Side joints remain open jointed and are set
being set near a horizontal plane. Since pan-
MCR_ 53
Metal 04 Rainscreens 1
1
1 2 3 2
4
5
10
Details 1. 2. 3. 4. 5. 10
Section 1:10. Concealed parapet gutter
6. 7. 8.
Detail D
Metal rainscreen panel Single layer membrane Closed cell thermal insulation Structural deck Purlin or structural beam Secondary purlin Folded metal gutter Folded metal drip
9. Metal fascia panel 10. External wall 11. Outer sheet fixing bracket 12. Panel 1 13. Panel 2 14. Ridge piece 15. Structural frame 16. Pipe or duct penetration
Section 1:10. Concealed parapet gutter with cantilevered edge 1
3
4
9 5
10
els must have the ability to be removed easily
rim.This allows the screw fixings to be con-
and regularly for maintenance access, screw
cealed from view, while allowing each roof
fixings in all panel corners are most com-
panel to be removed without affecting adja-
parapets is that the gutter and upstand can
monly used. Concealed fixings are more diffi-
cent panels.
be made without either element being visi-
cult to accommodate, though such systems
An alternative fixing method for panels is
Parapets An advantage of rainscreen panels for
ble. Consequently, eaves, monopitch ridges
are likely to appear over the next 10 years as
to set screws in each corner of the face of
and verges can have a similar outward
demand for this roof system increases.
the panel onto a support rail system, as
appearance of an uninterrupted panel layout
Panels are made usually by folding the
shown in (C). Screw heads are difficult to
extending from roof down to the external
edges down to form a tray, then outwards to
coat in a colour that matches the panel, and
wall. Parapets are formed only by a gutter
form a rim around the panel, as shown in (B).
even if this is achieved, then scratching of the
that also provides the necessary upstand
Holes are drilled at the corners to allow
panel is likely as a result of removing panels
height for the parapet itself. A coping is then
access to screw fixings beneath. Short lengths
for maintenance access. Screws are usually
formed by using the same rainscreen panels
of bracket are bonded or riveted to the sides
left as a self-finish, and have a particular
as elsewhere on the roof in order to provide
of the tray beneath the projecting panel rim.
appearance when viewed as a complete set
a continuity of appearance.The waterproof
The panels are then screw fixed at the brack-
of roof panels. Countersunk screws have the
membrane beneath is then sealed against
ets to the supporting rails or Z-sections by
least visually obtrusive appearance.
the wall construction or against the side of
passing the screw through the hole in the
MCR_ 54
the sealed roof deck, which is closed off with
1
2
3
4 9
10
10
Section 1:10. Monoridge with curved fascia panel
Detail E
Section 1:10. Monoridge with cantilevered edge
1
3
9
2
4
5
10
a folded metal strip, in the case of profiled
The parapet gutter can be covered with
tinuous with the external wall beneath.The
metal sheet or composite metal panels being
a perforated or slotted metal cover in the
rainscreen panel at the edge of the roof is
used.
same material and finish as the adjacent rain-
linked directly to a fascia panel. In (E) a
screen panels. Since rainwater runs off each
curved panel is shown which is structurally
then finished with another rainscreen panel,
panel at its edges onto the membrane
independent of the external wall beneath.
set vertically, which is fixed in front of the
below, there is no need to leave the gutter
This allows the roof deck to deflect and
parapet. Unlike parapets in profiled metal or
uncovered, as is the case with other metal
move under normal structural loading with-
composite panels, the vertical fascia panel
roof systems.Water running down the
out affecting the wall beneath. If wall and
can extend up to the top of the wall in
membrane is drained directly into the gutter,
roof were rigidly fixed together, the wall
order to conceal the coping flashing. In other
and water underneath the gutter cover
would deflect with the roof, to amount that
types of metal roofing, the coping extends
drains through slots or perforations.
would be too much for curtain wall systems,
The depth of the roof construction is
over the top of the wall, resulting in a thin visual edge to the top of the wall.This coping line can be concealed from view in rain-
whose movements are very restricted.This is
Monopitch ridges and verges These ridge types, as shown in (D) are
a common detail for roofs where the expected structural movements are higher
screen roof panel construction.The external
formed by sealing the waterproof mem-
than the modest movements allowed with
wall beneath is typically sealed up to the
brane against the side of the roof deck to
curtain wall facades.
underside of the roof deck.
provide a watertight enclosure that is con-
A seal between the external wall and
MCR_ 55
Metal 04 Rainscreens Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.
1 2 3 4
9
10
Metal rainscreen panel Single layer membrane Closed cell thermal insulation Structural deck Purlin or structural beam Secondary purlin Folded metal gutter Folded metal drip Metal fascia panel External wall Outer sheet fixing bracket Panel 1 Panel 2 Ridge piece Structural frame Pipe or duct penetration
10
Section 1:10.Verge with projecting fascia panel Section 1:25.Typical section with rainscreen panels draining directly to membrane 1
2
1
3
15 2
the underside of the roof is provided by two
solution is to introduce a gutter at the edge
directions. Panels are increasingly being twist-
layers of EPDM sheet with flexible insulation
of the verge to give greater height to the
ed in two directions in order to create gen-
quilt set between them. Folded metal sheet
verge upstand without it becoming visible,
uinely curved roof finishes. Alternatively, pan-
can also be used, but is less flexible in the
and without breaking the continuous line of
els can be set flat but with each panel set at
longitudinal direction (along the length of the
rainscreen panels.
different angles to create a facetted roof sec-
roof) than EPDM sheet. Verges are similar to monopitch ridges, but differ in that they require an upstand at
tion.
Roof geometry An advantage of rainscreen panels is
Although the drawn examples here show lightweight roof configurations to suit
the roof edge to prevent rainwater from
their ability to form complex geometries
the lightweight nature of the metal rain-
spilling off the roof.The upstand can be low if
from flat panel components. Since the panels
screen panels, any compatible roof substrate
the verge is flat, and if relatively small
are not required to be waterproofed, they
can be used, from reinforced concrete slabs
amounts of rainwater are flowing along this
do not require any joints between panels
to timber shell structures.
edge of the roof. If large amounts of water
that would become difficult and expensive
flow are expected then the roof can be
for roofs with complex geometries. Flat pan-
around 100mm above the membrane, some
angled upwards slightly to avoid an upstand
els can be fixed down at their corners on a
can be up to 1000mm above the roof deck
that extends above the line of the rainscreen
curved roof to create a set of gently curved
in order to accommodate mechanical plant
roof panels, as shown in (F). An alternative
panels that are turned in either one or two
equipment and duct outlets for mechanical
MCR_ 56
Although most rainscreens are set at
12
13
2 3 4
Shimosuwa Municipal Museum, Lake Suwa, Japan. Architect:Toyo Ito & Associates
Section 1:10. Panel fixing
Section 1:25.Typical section with rainscreen panels draining from panel to panel
1
1
4
ventilation within the building.This allows
a complete soffit to the underside of a roof.
in the past 10 years, making this a roofing
rainscreen panels to provide weather pro-
When mixed with perforated or slotted
method set for new developments.
tection for equipment as well as a visual
panels and louvres, a roof can become a sin-
screen to these items, which can have a con-
gle visual entity, set above its external walls
siderable visual impact on a roof. Rainscreen
as a separate and distinct element.This can
panels set 1000mm above the roof are fixed
be achieved without the need for an expen-
to a secondary support framework, typically
sive structure, or for an expensive water-
of cold formed steel sections or aluminium
proofing layer, since the membrane is con-
extrusions.The framework is fixed at its base
cealed from view and is chosen for its per-
to pads or Z-section profiles in the same
formance rather than for its visual qualities.
way as the rainscreens set close to the roof
The easy removal of panels for maintenance
membrane.
access both on the roof, and into the ceiling void from the soffit panels beneath, make it
Roof soffits Metal rainscreen roof panels can also be
an economic and easy to use system for roofs of complex geometry.The range of
used as soffits panels to either an overhang-
colours for composite sheet and for coatings
ing eaves or parapet, or alternatively to form
to sheet metal have increased considerably
MCR_ 57
Metal 05 Metal canopies
2 1
6
3
Section 1:25. Canopy edge The Giovanni and Marella Agnelli Art Gallery at Lingotto,Turin, Italy. Architect: Renzo Piano Building Workshop
Section 1:80. Canopy assembly
Example B
1 6
6
3
3
Metal canopies use all the techniques avail-
tures, but with the more durable finishes
native method of joining metal panels
able to metal: standing seam, profiled sheet,
associated with metal panels. In common
together is by riveting them together, leaving
composite panel and rainscreen panels with a
with other canopy types, metal canopies are
a hairline joint between the sheets.This is
membrane beneath. However, the preferred
expected to be fully watertight.The generic
done either by butting flat sheet together
technique for metal canopies is usually none
example here follows this principle.
and riveting the two sides together as (C), or
of these, but instead a method suited to
In generic example (A) the metal canopy
by folding the sheets down and riveting the
small-scale construction of complex geome-
also serves as a sealed roof to part of a
underside as (D). In (C), the sheets are fixed
try.This method uses metal panels with fold-
glazed wall. An inclined glazed wall meets a
with countersunk rivets fixing the edges of
ed edges, sometimes called cassettes, the
metal canopy at mid-height which might
each sheet in place. A compressible polymer
joints between panels being sealed with sili-
form part of an entrance, or may serve as
sheet is set beneath the sheets to provide a
cone sealant. Panels can be individually folded
solar shading to a facade.The sealed outer
weathertight seal. In (D) a similar sheet
to different shapes to form a canopy of com-
layer of the canopy comprises metal panels
material is set between the riveted panels to
plex geometry.There has been a gradual
which are folded to form an overall curved
provide a seal. In practice, seals (C) and (D)
move towards larger metal panel sizes, even
profile, each panel being made from metal
are difficult to achieve where a high weath-
a complete form made from metal coil,
sheet which is folded at its edges to form a
ertight performance is required. Instead, the
which imitates the homogeneous forms
tray.The folded edges form the surface to
seal (E) used in the generic example shows
found in GRP membranes and tent struc-
which the silicone sealant adheres. An alter-
silicone seal around 10mm wide between
MCR_ 58
1
6
Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.
Extruded aluminium louvre blade Mild steel box section Mild steel tube Structural pin connection Mild steel I-section Bolt fixed metal panel Aluminium sheet Mild steel or aluminium support frame Thermal insulation Silicone seal Glazed wall
3
3
Section 1:25. Canopy edge and support
Isometric view of assmebly: Electrically operated louvres
Sections 1:10.Typical louvre sections
Sections 1:10.Typical louvre sections
Detail H 5
Detail J 5
1 1
panels which are fixed with brackets back to
smooth and consistent, and this is usually
ver-grey colours match well with silver
a supporting structure.This provides a reli-
accepted visually as part of their appearance.
coloured panels to give an overall appear-
able seal that maintains its weather tightness
If much thicker sheet is used, there is a disad-
ance of a single colour for the complete
in the long term.
vantage in increased cost as well as a greater
canopy, particularly when recessed joints are
difficulty in working the sheet to form
used between panels, shown in (B). Flush
either mild steel or aluminium sections. Alu-
The supporting structure is made from
smooth shaped pressed panels. Aluminium
joints in silicone tend to give the canopy sur-
minium sections are usually preferred for
panels are typically either PVDF coated or
face an homogenous appearance, giving it
their durability but mild steel is often used
polyester powder coated, while steel sheet is
more the appearance of concrete than of
for its greater rigidity. Mild steel is galvanised,
usually polyester powder coated only.The
metal.This can detract from the crisply fitted
painted, or both, while aluminium, with its
use of anodised aluminium as a finish on
assembly of panels which is characteristic of
greater durability, can be natural, anodised or
sheet has increased in recent years as a
metal and also one of the advantages of the
cromated (similar to anodising) depending
result of greater reliability of the finish, which
material.
on the individual application. Metal panels of
until recently has suffered from uneven
large size, made from 1200mm x 2400mm
colour consistency. In generic example (B)
set of assembly techniques available to the
sheet, can result in a gentle oil-canning effect
the silicone used to seal the joints can be
material within a single assembly.With folded
around their edges.This gives panels their
applied in a variety of monotone tints, rang-
panels, the edges are welded and ground
characteristic soft edge, but they look
ing from white, to greys, to black. Some sil-
smooth, and the complete panel is coated to
Metal panels can bring together the full
MCR_ 59
Metal 05 Metal canopies Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.
Extruded aluminium louvre blade Mild steel box section Mild steel tube Structural pin connection Mild steel I-section Bolt fixed metal panel Aluminium sheet Mild steel or aluminium support frame Thermal insulation Silicone seal Glazed wall
Plan and section 1:200.Typical canopy asembly
a single consistent colour.The use of counter-
folded under the bottom transom.The metal
ventilated internal drainage system of the
sunk screws, painted on site in a colour
sheet forming the top of the canopy
glazed wall framing.The metal sheet forming
matching that of the panels, enhances the
becomes a vapour barrier on the internal
the underside of the canopy on its internal
overall appearance.
side of the wall, rather than the full weather
face is taken as close to the glass as possible
barrier used on the external face of the
before being folded back to align with the
canopy.
transom.
In generic example (B) the glazed wall above the canopy is sealed to it by extending the metal sheet forming the external gutter
The glazed wall on the underside of the
Metal canopies are increasingly using a
up into the bottom transom (horizontal glaz-
metal coping is joined in a way that disturbs
single seal between panels to form a weath-
ing bar) of the glazing system to form a con-
the line of the canopy as little as possible as
ertight joint.This method uses the applica-
tinuous seal with the glazed wall above.The
it passes it from outside to inside.The metal
tion method of bolt fixed glazing, where a
thermal insulation within the canopy is con-
sheet on the exterior face of the wall is
reliable silicone seal between double glazed
tinued in order to meet the thermally broken
glazed into the top transom of the wall
units is the norm. However, where a foam-
transom where it forms a continuity with the
below. Any excess rainwater that is blown
based backing rod is used to support the sili-
double glazed units above.The metal sheet
into the joint drips off the top of the tran-
cone applied from the outside, workmanship
forming the top of the canopy on the inter-
som pressure plate and capping. Small
on site must be of the highest quality to
nal side of the wall is lapped up the internal
amounts of rainwater that find their way into
ensure a durable weathertight seal.Where
face of the glazed wall framing where it is
the transom are taken away through the
this is difficult, as where the edge of the
MCR_ 60
5
1
1
1 2
1
1
Section 1:10. Junction of louvre panel and frame.
Section 1:25.Typical louvre panel
Detail K
Electrically operated louvres
Plan 1:80.Typical louvre panel
5
Detail G
Detail F
1
5 1
panel has a small edge return, or where pan-
ite sheet can be bolt fixed using proprietary
temperature of the building. An alternative is
els are not able to be very rigid due to their
systems destined for use in point fixed glaz-
to form the insulation with the shortest dis-
geometry or manufacturing method, a sec-
ing.The use of oversized holes or slotted
tance between the glazed walls above and
ond line of defence for weather tightness is
holes in the metal panel ensures that the
below, so that the structure and void are at
provided by an elastomeric or thermoplastic
metal panels can move with thermal expan-
the external temperature.The warm roof
waterproof membrane.The ends of the
sion without bowing or bending.
solution is usually preferred.
waterproofing sheet at their top and bottom
Gutters and rainwater outlets can be
Fixed metal louvre canopies
ends are fixed into the glazing system above
formed in sheet metal as shown in (B).The
and below where small amounts of water
rainwater outlet can be finished to match
that penetrate the outer silicone seal are
the adjacent metal finishes so as not to
as canopies to provide solar shading while
allowed to drain to the outside.
detract from the overall visual form of the
still allowing daylight to pass through the
canopy.
canopy. Louvre blades are set typically at 45°
Bolt fixed panels
In (B) the canopy forms part of a glazed
Arrangements of metal louvres are used
to the vertical in order to block the passage
wall, and is thermally insulated.The insulation
of direct sunlight but allow the light to be
on the canopy edges in generic example (A).
usually follows the form of the outside of the
reflected off its surfaces down to the space
With flat panels, such as minimum 3mm
canopy to keep the voids within the struc-
beneath the canopy. Louvre sections are cre-
thick aluminium sheet, and metal / compos-
ture at a similar temperature to the internal
ated from folded strips of aluminium or mild
Metal panels can be bolt fixed, as shown
MCR_ 61
Metal 05 Metal canopies Example A Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.
11
Extruded aluminium louvre blade Mild steel box section Mild steel tube Structural pin connection Mild steel I-section Bolt fixed metal panel Aluminium sheet Mild steel or aluminium support frame Thermal insulation Silicone seal Glazed wall
7
7 9
8
7
7
8
Plan and section 1:20.Typical metal canopy
Example A
The Giovanni and Marella Agnelli Art Gallery at Lingotto,Turin, Italy. Architect: Renzo Piano Building Workshop
11
11
9
7
steel sheet, but these have limited stiffness
profile has screw ports that form part of the
sections are shown bolted together to form
and stability, requiring restraint along their
extrusion, into which the screws are fixed, as
a flat frame structure, into which are set lou-
length to hold their straightness in length.
shown in (K). Aluminium extrusions can be
vre panels, prefabricated and finished in a
Greater stiffness is provided by extruded alu-
made in lengths up to around 6000mm, and
factory, then fixed to the supporting mild
minium sections, where the elliptical section
are supported at centres to suit their struc-
steel frame on site.The steel tubes are fixed
is most commonly used, mainly for its ability
tural depth. An elliptical section will span typ-
to the flat frame with pin connections.Two
to reflect daylight in a way that reveals its 3-
ically 1500mm for a 75mm to 100mm deep
flat plates are welded to the ends of the
dimensional form, enhancing its appearance.
section while a 250mm deep section will
tubes, and a single plate forming a cleat is
Sections are either a half ellipse as (H) or a
span 2500mm, depending upon design wind
fixed to the underside of the flat frame and
full ellipse as (J). Flat louvre arrangements
speed and related loads.When fixed at their
the base support below the roof.The fork
provide much less visual vibrancy when
ends, as shown in generic example (B), a
ends of the tubular supports and the sup-
viewed from below. Extruded aluminium sec-
fixed louvre assembly can be made without
port cleats to which it connects are fixed
tions require end caps, usually for visual rea-
visible fixings.
together with face-mounted or countersunk
sons, and these are either fixed with counter-
The supporting structure in (B) compris-
bolts to form a visually crisp connection.The
sunk screws into the wall of the section, or
es a mild steel frame fabricated from box
tubes have tapered ends shown which is
are welded and ground smooth.Where end
sections, supported by tube sections that
typical of this type of steel construction.The
caps are screwed to the ends, the aluminium
spring from points below the roof.The box
aluminium louvre panels are fixed to the
MCR_ 62
Plan and section 1:20.Typical metal canopy Example A 7
8
9
11
Plan, section, elevation 1:100.Typical metal canopy Example A
7 11
11
8
Joint types 1:2
Detail C 7
11
11
Detail D
Detail E
the two diagrams of (F) and (G).
supporting flat frame with brackets that are
metal, to avoid the need for regular lubrica-
welded to the sides of the bottom flange of
tion. Louvres can be solid or perforated to
the steel I-section.The aluminium louvre
different percentages of solid to void, from
around 6000mm long for those 75mm to
panel is supported on these brackets, with a
around 10% void to a maximum of 50%,
100mm deep, requiring support at 1000mm
nylon spacer between them to allow for
though the latter is difficult to fabricate.
to 1500mm. Sliding arms typically support
Louvres are typically a maximum of
thermal movement.The louvre panel is fixed
Louvres are fixed by steel pins into a
up to a 6000mm length of louvre blades, giv-
to the cleat bracket with a countersunk bolt.
sliding aluminium section at each end of the
ing an overall square shape (in plan) to each
profile, as shown in (F) and (G).The louvres
set of controlled louvres of 6000mm x
are also fixed at their centre in section. As
6000mm size which are fixed into the sup-
Electrically operated louvres
the sliding aluminium rod moves, the alumini-
porting I-section frame. A 100mm deep I-
zontal and inclined glazed roofs, excluding up
um louvres move together, opening and clos-
section will span typically 1000mm -
to 90% of solar heat gain when set at a 45°
ing together.The sliding rods are connected
1500mm between supports depending on
angle. Louvre blades are 75mm-100mm in
at each end of the louvres are fixed to a
the design of the glazed roof below.The dis-
typical proprietary systems but blades up to
supporting frame of aluminium I-sections.
tance between the moveable louvre panels
300mm wide can be made as a single extru-
The single tube is powered by an electric
and the glazed roof below is made sufficient
sion. Nylon sleeves and washers are used at
motor, and as it turns, the sliding arms move
to allow for access for cleaning the glass
the connection of moving parts, rather than
through the arrangement of gears, shown in
below and the louvre assembly itself.
Louvre canopies are also used for hori-
MCR_ 63
2 GLASS (1) Greenhouse glazing and Capped glazing Greenhouse glazing Modern roof glazing Capped systems (2) Silicone-sealed glazing and Rooflights Junctions Use of capped profiles Rooflights (3) Bolt fixed glazing Generic structural support methods Supporting brackets Bolt fixings Arrangement of bolt fixings Glazed units (4)Bolt fixed glazing: Pitched roofs and rooflights Base of glazed roof External and internal folds Small glazed rooflights Larger rooflights (5) Bolt fixed glazing: Twin wall roofs (6) Bonded glass rooflights Generic conical rooflight Generic rectangular rooflight Generic monopitch rooflight Glass roof decks (7) Glazed canopies System assembly Four edge restrained canopy Bonded glass canopies
MCR_ 65
Glass 01 Greenhouse glazing and Capped glazing systems
2 3
1
1
Section1:25. Greenhouse glazing. Typical ridge section.
3 4
2
3
Section1:25. Greenhouse glazing. Typical section. Section1:25. Greenhouse glazing. Typical cross section.
Isometric view of roof assembly
Detail A
Detail D
Section1:25. Greenhouse glazing. Abutment.
1 3
4
4
2
7 8
Greenhouse glazing
thicknesses being used typically.The lapped
set typically at 3000mm centres with purlins
glass results in water being drawn up
running between them to support the glaz-
nal walls have been adopted, over the last 20
between the sheets by capillary attraction,
ing bars at 600mm centres.
years, as a reliable method of constructing
which can cause water leaks and staining.
glazed roofs to replace earlier systems devel-
However, complete weather tightness is a
houses for agricultural activities, but has poor
oped from greenhouse glazing.Traditional
secondary issue in greenhouses, this design
thermal insulation, since their purpose is to
greenhouse glazing used thin steel or cast
being a very neat and economic solution for
absorb the heat from the sun rather than
iron sections to support glass sheets on their
its purpose.
excluding it.The use of single glazing, with no
Curtain walling principles used in exter-
vertical edges to form a pitched roof. Since
The glazing can be used in a pitched
This glazing system is still used in green-
thermal breaks and high air infiltration rates
rainwater needs to run down the slope
roof as well as a vertical wall to form the
(by curtain walling standards), make it ideal
without being impeded by glazing bars, a
traditional greenhouse enclosure. For large
for agricultural use, but very poor for the
method of lapping glass sheets over one
greenhouses an additional aluminium or
use in general building construction. Howev-
another was used, as shown in (A).Tradition-
steel frame is used to support the glazing. A
er, the concept of greenhouse glazing has
ally, the glass is lapped with no seal, with glaz-
typical structure is of lightweight metal truss-
been developed into the highly insulated, air
ing bars set at around 600mm centres in
es, used to support the glazed roof, are set
sealed and watertight glass roof systems
order to keep the glass as thin as possible,
on steel or aluminium box section columns
used in contemporary buildings.
with glass thicknesses from 4mm to 6mm
that also support the glazed wall.Trusses are
MCR_ 66
An essential component of greenhouse
4
4
4
4
2
7
Section1:5. Greenhouse glazing.Valley Section1:5. Greenhouse glazing. Eaves
Detail F
Greenhouse details 1. 2.
1
Section1:5. Greenhouse glazing. Ridge
3. 4. 5. 6. 7. 8.
Extruded aluminium glazing bar Extruded aluminium sections Single glazed sheet Double glazed unit Aluminium clip-on capping Polycarbonate sheet Aluminium gutter Concrete base
Section1:5. Greenhouse glazing. Polycarbonate to glass junction Detail E 5
6 3
4
6
1
1
Amazonian House, Stuttgart. Architect: Auer und Weber
Section1:5. Greenhouse glazing. Detail C 6
6
3 1
Glass to glass junction. Detail B 6 3
1 8
glazing that has been retained in modern
glass sheets is sealed with either a clear
are held in place on the aluminium glazing
glazed roofs is the glazing bar, which corre-
coloured seal, typically silicone sealant, or
bars and which press against the glass to
sponds to a mullion in glazed walls.The
with continuous aluminium clips. Some
provide both a cushion for the glass as well
greenhouse glazing bar has a condensation
greenhouse systems still have lapped glass
as a water and air seal.The strength and stiff-
channel beneath of the glass to drain away
with no seal between the glass sheets, mak-
ness of the glazing bar is provided by the
water that passes through the outer seal dur-
ing it very economic, but not very airtight,
central flat bar that extends beyond the glaz-
ing rain.The condensation channel also
which suits certain agricultural applications.
ing line either inside or outside the glazing.
serves as a drain for moisture inside the
Ventilation in greenhouse glazing is pro-
Unlike curtain walling based systems, where
building that has condensed within the fram-
vided at the eaves and at the ridge, while
the structural mullion extends on the inside
ing. Condensation channels are either open
opening lights are used for more closely
face of the glass, with a pressure plate on the
at the edges, as (B), or are enclosed as (C).
controlled ventilation. Single glazed sheets
outside, greenhouse glazing has only clips
Modern greenhouse glazing is made from
are held in place on their sides by support-
either side of the control bar, allowing it
extruded aluminium sections with no thermal
ing them on the glazing bars and securing
greater freedom to extend both inside and
break, since high thermal insulation is not
them in place with continuous aluminium
outside the face of the glass.The rubber
required, but includes the condensation chan-
clips that snap onto the glazing bar.The alu-
seals are deep enough and soft enough to
nels to avoid water from dripping below.
minium sections are separated from the
allow the bottom of the glass sheet to lap
glass by extruded rubber-based seals which
over the top of the sheet below on the hori-
The horizontal joint between lapped
MCR_ 67
Glass 01 Greenhouse glazing and Capped glazing systems 6 1
4
2 6
1
2
1
2 1
2 6
Section 1:10. Capped glazing. Eaves with glass to glass fold
Section 1:10. Capped glazing. Eaves gutter
Section 1:10. Capped glazing.Valley gutter
2
Detail J
1
4
Section 1:10. Capped glazing. Eaves with profiles at fold 1
Section 1:10. Capped glazing. Ridge
2 8
8 6
4 5
1
1
7
zontal joints. Greenhouse glazing can accom-
horizontal joints are usually sealed with sili-
45°. A condensation channel set into the
modate double glazing units, as shown in (D).
cone to provide an air seal. Greenhouse sys-
glazing section is drained either into the glaz-
The main reason for this is usually to provide
tems can also accommodate both flat poly-
ing bars that intersect with it, which drains
greater control of the internal temperature
carbonate sheet and the multi-wall type. A
down the slope of the roof to the eaves, or
for agricultural buildings.Thermal breaks are
twin wall sheet has thicknesses with are simi-
is drained at its gable ends if the ridge can
still not required, but there is a larger provi-
lar to those of double glazed units, ranging
be set level to allow the water to drain
sion for slot ventilation at the ridge and eaves
from around 24mm to 32mm, allowing the
freely.
locations to encourage natural cross ventila-
same aluminium profiles to be used for both
tion.The increased weight of double glazed
double glazing and polycarbonate sheets, as
files to a box section used at junctions
units over single glazed sheets results in big-
shown in (E).
beneath it.The glass simply overhangs the
ger glazing bars to support them, but the sys-
Gutters are formed by fixing gutter pro-
Ridges are formed by special extruded
edge of the roof to drain rainwater into the
tem remains essentially the same.The snap-
aluminium sections that hold the glass with
gutter. At ground level, the glass often over-
on glazing clips or screw-on types in use usu-
the same clips used for the glazing bars
laps the concrete ground slab, where a fin-
ally have a stepped profile to accommodate
which meet at the ridge. Since each ridge
ished floor is provided.Where the green-
the increased glass depth, while short length
extrusion can suit only one roof pitch, manu-
house glazing has no floor, as is the case in
aluminium clips are used along the horizontal
facturers offer ridge profiles to suit a limited
many agricultural applications, a brickwork or
joints to hold the lapped units in place.These
range of roof pitches, typically 22°, 30° and
concrete blockwork edge is provided to ter-
MCR_ 68
Detail H
Detail G
6
6
4
3
4
6
1 1
1
2
1
Section 1:10. Capped glazing.Typical profiles
Capped glazing details
Isometric view of roof assembly
1. 2. 3. 4. 5. 6.
Extruded aluminium glazing bar Transom Single glazed unit Double glazed unit Ridge bar Pressure plate and capping
7. 8. 9. 10. 11. 12. 13.
Section 1:10. Capped glazing. Parapet upstand.
4
Insulated gutter Insulated flashing Rooflight Thermal insulation Pressed metal flashing Concrete base Pressed metal trim Detail K
4
6 1 5
1 2
2
1 8
12
minate the glass above ground level, where it
weight of a gutter filled with rainwater.
principles of glazed curtain walling. Drained
could otherwise be susceptible to damage.
Although not useful for most applica-
Valley gutters, which occur typically
tions in general building construction, green-
mal breaks and double glazed units. Pressure
where glasshouse roofs are set next to one
house glazing is useful for the reader for two
plates rather than clips are used to hold
another, are also formed from extruded alu-
reasons: to understand how glazed roofs
large glass units in place in capped systems,
minium sections, with the glass being secured
have evolved from a simple mass produced
and toggle-type plates are used to provide
in the same way as the glazing bars, as
system, as well as for applications where a
flush joints in silicone based systems.This lat-
shown in (F). An additional upstand is often
glazing system is required that is minimal in
ter type is discussed in the next section of
added to the aluminium section for
both its components and its overall assembly
this book, while this section focuses on pres-
increased rigidity. Gutters in other roof sys-
as well as where an uninsulated glass struc-
sure plate based, or 'capped' systems.
tems are usually insulated, where the depths
ture might be required, without the need to
of insulation, together with the inner lining,
use thermally broken glazing systems which
provide a rigid gutter.With greenhouse glaz-
are designed for much larger glass units.
ing, with no thermal insulation provided, an upstand or downstand formed within the gutter extrusion performs the same function of providing sufficient stiffness to bear the
and ventilated systems are used, with ther-
Capped systems The system shown in (G) comprises glazing bars which are assembled on site in a
Modern roof glazing Systems for glass roofs use the principles of greenhouse glazing, but incorporate the
grid of members that resemble the mullions and transoms of stick glazed curtain walling. The base of the curtain wall, at the bottom
MCR_ 69
Glass 01 Greenhouse glazing and Capped glazing systems 6
4
4 4
9
1
1
2
5
11
2. 3. 4. 5. 6.
Extruded aluminium glazing bar Transom Single glazed unit Double glazed unit Ridge bar Pressure plate and capping
6
Section 1:10. Capped glazing. Junction with rooflight
Capped glazing details 1.
10
7. 8. 9. 10. 11. 12. 13.
Insulated gutter Insulated flashing Rooflight Thermal insulation Pressed metal flashing Concrete base Pressed metal trim
6 1
1
2
Section 1:10. Capped glazing. Parapet upstand 4
Section 1:10. Capped glazing.Typical profiles
6
Section 1:10. Capped glazing. Abutment Section 1:10. Capped glazing. Ridge
1
6
11 2 4
4
10
5 1
1
of the extruded profile, may have an addi-
without eaves, where the roof angle changes
tems use a pressure plate and cover capping
tional condensation channel, as shown.This
from pitched to vertical wall, rainwater is
with chamfered edges that allows rainwater
provision can also be made by setting the
allowed to run on down the wall to the base
to pass over it easily. A small amount of
condensation channels immediately beneath
of the roof. At the 'fold' point of the roof
water is left trapped on the top edge of this
the glass, as shown in (H).The glass is set
the internal drain in the glazing bar is contin-
horizontally-set glazing bar, but this is soon
onto rubber-based air seals fixed to the glaz-
uous with the vertical wall, and the system is
blown away by the wind or else evaporates.
ing bar and is secured with a continuous
drained at the base of the wall, which could
Any water that penetrates the outer seal is
pressure plate of extruded aluminium. A strip
be a reinforced concrete slab at roof level.
drained away through the internal drain in
of extruded EPDM is set between the pres-
While glazing bars running down the
the glazing bar.
sure plate and the glass to provide a weath-
roof project above the surface of the glass,
ertight seal. As with glazed curtain walling, the
those running along the roof, holding in
principles of greenhouse glazing.The box
glazing bars are drained and ventilated, or
place the top and bottom edges of the glass,
section, or chosen profile of the typical glaz-
pressure equalised, internally.Water that is
require a method of allowing the water to
ing bar is usually made deeper to take the
able to find its way through the outer seal
run over the junction. Some systems use a
higher structural loads of the ridge. Glazing
drips into an internal channel where it is
step at this point, without a pressure plate
bars that intersect with the ridge profile are
drained away safely to the bottom of the
on top that would otherwise impede the
notched at the top to allow the drained and
roof, typically at the eaves. In smaller roofs
passage of water down the roof. Other sys-
ventilated inner chamber to drain water
MCR_ 70
Ridges, like glazing bars, follow the main
Section 1:10. Capped glazing. Ridge
11
6
6
4
4
1
1
Amazonian House, Stuttgart. Architect: Auer und Weber
Section 1:10. Capped glazing. Junction with rooflight
Plan and section 1:100. Capped glazing. General principle
Section 1:10. Capped glazing. Parapet upstand
1
2
6 1
2
4
9
6
2 10
4
1 13
2
12
internally down the glazing bars that follow
the relatively high level of thermal insulation
that terminate at flashings and gutters allow
the slope down the roof. A specially made V-
and to avoid a thermal bridge across the sys-
the internal drain to release water at these
shaped continuous pressure plate is used to
tem. If a downstand flashing is used to sepa-
points. Drops of water that find their way
secure the glass at the ridge, with a similar
rate the roof from the gutter, to make it eas-
into the drainage chamber are drained out
shaped cover cap set on top.While cover
ier to install the gutter, then two layers of
onto the outer (top) surface of the down-
caps are not an essential part of glazed
flexible membrane seal are used between
stand flashing.
roofs, as is the case with curtain walling, their
the downstand insulated flashing and the
function is to conceal the drainage slots and
insulated gutter.This seal is required to be
screw fixings in order to provide a consistent
fully watertight if the gutter becomes
visual finish to the glazing bars.
blocked and water in the gutter fills to the
Gutters, at both valleys and eaves, are very different to greenhouse glazing. Instead of lapping the glass into the gutter, the gutter
top of the gutter during a storm, for example. Regular downstand flashings, shown in
profile (or downstand flashing) is clamped
(K), are insulated in order to provide a conti-
into one side of the horizontally-set glazing
nuity with the thermal insulation of the adja-
bar at the base of the pitched roof, as shown
cent construction at the base of the roof in
in (J). An insulated gutter is used to maintain
order to avoid a thermal bridge. Glazing bars
MCR_ 71
Glass 02 Silicone-sealed glazing and Rooflights
4
3 1
Cross section1:10. Junction with adjacent roof Detail F
Detail E 3
3
4
Cross section1:10. Junction with adjacent roof Cross section 1:10. Corner
4 DG Bank, Berlin, Germany. Architect: Gehry 3
8
Silicone-sealed systems
continuous around its perimeter.The extrud-
at 300mm centres.The gap between the
ed aluminium channel is recessed into the
glazed unit is sealed with silicone, typically
previous section, suit pitched roofs, they can-
gap at the edge of the unit usually used to
15mm to 20mm wide, and with a backing
not reliably be used on (nominally) flat roofs,
bond the unit together and to seal the edges
strip or 'backing rod' behind it to form a
where the roof pitch is usually 3° to 5°.This
behind the spacer.The adjacent spacer in the
back edge to the silicone seal.
is mainly because the rainwater running
double glazed unit both keeps the glass at a
down the roof cannot pass the horizontal
fixed distance apart as well as having desic-
box or fin removed in order to fix it directly
glazing bars which project above the surface
cant within it to absorb any residual mois-
to a steel support frame. Square hollow sec-
of the glass.The smooth, continuous finish
ture within the sealed cavity between the
tions are shown here. Alternatively, an all-alu-
required for flat glazed roofs is achieved with
glass sheets.The recessed aluminium channel
minium glazing bar can be used, as shown in
a silicone seal between glass panels that is set
is bonded to each glass sheet and also pro-
(B). As with capped systems, small amounts
flush with the surface of the glass.The glass is
vides the edge seal to the completed unit, as
of rainwater that pass through the outer sili-
clamped in place with short lengths of pres-
in a regular double glazed unit.The short
cone seal are drained away in the condensa-
sure plate that are recessed below the outer
lengths of pressure plate are then set into
tion channels set below the glass, within the
seal.The recessed plates are secured to an
the gap formed by the recessed channels of
glazing bar. In practice, silicone seals are very
aluminium channel which forms an integral
abutting glazed units, and are clamped to the
reliable but are dependent upon good work-
part of the double glazed unit and which is
glazing bar with self tapping screws, typically
manship on site, so the condensation chan-
While capped systems, described in the
MCR_ 72
In (A) the glazing bar has its structural
Section1:25.Typical assembly
3
Plan 1:50.Typical layout
3
Plan 1:5. Corner
Details Extruded aluminium glazing profile 2. Pressure plate and capping 3. Mild steel support frame 4. Double glazed unit with recessed edge 5. Insulated metal panel 6. Silicone seal 7. Glazing channel 8. Concrete base 9. Adjacent opaque roof 10. Rubber-based glazing profile
3
Plan 1:5. Panel to panel junction
1.
Detail C 4
4
4
2
2
Long section1:10. Horizontal panel to panel junction 2
4
3
3
3
nel is often not used in practice but serves
required angle, while the glazing bar forming
carried away in a gutter, but in practice
as a secondary chamber to support the
the ridge is the same as that used elsewhere
glazed rooflights require regular cleaning to
inner air seals. Silicone-sealed glazing bars
on the roof, with some modifications to the
maintain their crisp appearance.
can be used in all directions across a roof,
angle of the clips that hold the inner EPDM
unlike capped systems, since the glazing bars
seal in place.The edges of roofs are also
a single specially formed glazing bar, as (C),
present no barrier to the passage of water.
treated as folds, with rainwater usually
or with two glazing bars meeting as shown
allowed to run off the edge into a gutter,
in (D). In (C), the recessed lengths of pres-
either just below the roof, or down to the
sure plate are folded to form the required
base of the glazed wall below the glazed
angle, and the silicone is chamfered to form
systems is of continuous glazed surfaces
roof. An advantage of this system is the abili-
a flat surface between the two meeting glass
uninterrupted by visible glazing bars, ridges
ty of the roof to be continuous with a glazed
panels. Silicone is rarely used to make a
and valleys are treated as simply folds in the
wall in the same system with a simple 'fold',
sharp angle between the two double glazed
surface of the glazing, since rainwater runs
without reducing its weather tightness.Typi-
units as it is very difficult to achieve a straight
across the complete sealed surface of the
cally the wall is not very high, forming part of
line without the assistance of an additional
glass rather than being directed into gutters
a larger glazed roof. Dust that is carried
metal angle bedded into the silicone.The
across its surface.The short lengths of pres-
down off the roof during rain is washed
alternative method of forming a roof edge,
sure plate can be folded in the factory to the
down the vertical glazing, rather than being
as (D), requires the edge of the double
Junctions Since the advantage of silicone-sealed
The folded corner is formed with either
MCR_ 73
Glass 02 Silicone-sealed glazing and Rooflights
6 4 4 1
1
1
3 3
6
1
Section 1:5. Horizontal panel to panel junction with capping Detail A
Cross section1:5. Corner
Detail D
Section 1:5. Horizontal panel to panel junction without capping
Section 1:5.Vertical panel to panel junction with capping
Section 1:5. Horizontal panel to panel junction without capping Detail B Section 1:5. Junction with adjacent roof
Detail G
4 6 4 6 1
6
7
3 4
glazed unit to be coated or 'opacified' to
the thermal insulation is lined with a vapour
then a separate flashing can be used, fixed to
avoid the frame behind being visible through
barrier, typically a 3mm thick folded alumini-
the glazing bar but independent of the gut-
the glass.This is often achieved by stepping
um sheet.The opacifying of the glass is done
ter.The gutter is still sealed to the glazing bar
the glazed unit, with the outer glass extend-
by screen printing on the internal face of the
with a flexible EPDM gasket to provide a
ing to meet the corner, while the inner glass
glass.While black is often the preferred
continuous seal, as in (F).
stops at the glazing bar to allow the recessed
colour, in order to match with the silicone
aluminium angle to be bonded in its usual
seals, other colours and patterns are increas-
nates in a glazed wall can meet an adjacent
position adjacent to the glazing bar.The glass
ingly being introduced in glass manufacture.
concrete roof slab with either a metal glazing
Where a gutter is required, an insulated
channel, as (G), or in an upstand and flashing
unit is secured in the same way, with a
The base of the glazed roof that termi-
recessed length of pressure plate, while the
gutter is fitted to the glazing bar as shown in
as (F).Where a glazing channel is used, the
outer glass is cantilevered to meet the adja-
(E). Prefabricated gutters are used where
double glazed unit sits in a profile formed
cent glazed unit at the corner.Thermal insula-
they are seen from the underside, inside the
from extruded aluminium, stainless steel or
tion is bonded to the outer glass along the
building.They can be glazed into the system
painted mild steel.The glass is levelled on
cantilevered edge to form a continuity of
following the line of the internal face of the
metal shims (short lengths of metal strip)
thermal insulation, and avoiding a thermal
double glazed units.Where the gutter is
then sealed with silicone.The advantage of
bridge that will result in condensation occur-
required to be separated from the glazing
the glazing channel is that it can be set flush
ring in temperate climates.The inner face of
structures, typically for structural reasons,
with the finished internal level to provide a
MCR_ 74
Typical cross section 1:25. Capped glazing.Typical profiles
4
9
4
9
3
Typical long section 1:25. Capped glazing. Parapet upstand
4 4 4
3
3
Section 1:5. Horizontal panel to panel junction without capping
Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
4
Extruded aluminium glazing profile Pressure plate and capping Mild steel support frame Double glazed unit with recessed edge Insulated metal panel Silicone seal Glazing channel Concrete base Adjacent opaque roof Rubber-based glazing profile
junction with no visible horizontal glazing bar.
4
3
rarely presents any difficulty.
Alternatively, the glazing can terminate in a horizontal glazing bar, to which an aluminium flashing can be fixed. A downstand flashing is
Detail H
The most common application of this method is where capped profiles are used
Use of capped profiles An advantage of silicone sealed glazing
for the vertically-set glazing bars running down the slope of a roof, while silicone-
more easily fixed to a horizontal glazing bar
over fully bonded glazing (discussed in the
sealed glazing is used on horizontal joints to
than a glazing channel.The vertical glazing
next section) is its ability to be mixed with
allow rainwater to pass down it unimpeded
bars (forming the mullions) are fixed to
capped glazing. Since both systems are
by any projecting glazing bars. Junctions in sil-
brackets that are secured to the upstand. A
drained and ventilated (pressure equalised),
icone sealed glazing such, as edges of roofs
concrete upstand is shown in (F) with exter-
the same glazing bar can be used in a mixed
and ridges, are formed in the same way,
nal insulation and a single layer membrane.
roof system of flush silicone joints and
while the capped system follows the folds
The metal flashing extends down the face of
capped profiles. Although this mix is done
with continuous pressure plates that are
the upstand to protect the joint. As with gut-
often for visual reasons, it does allow for eas-
mitred and sealed at the folds. Butyl tape is
ters, an EPDM membrane extends down
ily formed junctions with adjacent areas of
used as an extra seal at folds, set between
from the horizontal glazing bar where it is
roof in different materials, and for a mix of
the pressure plate and the outer EPDM gas-
bonded to the membrane.The roofing
metal panels and glazed panels in a single
kets. Cover caps are also mitred to give a
membrane and the EPDM are always
roof using a reliable drained and ventilated
crisp appearance.
checked for compatibility, but in practice this
system.
MCR_ 75
Glass 02 Silicone-sealed glazing and Rooflights 4
4
3 3
3
Long section 1:10. Edge of rooflight
4
9
3
Cross section 1:10. Edge of rooflight. Long section 1:10.Typical profiles
6
4
9
6
9
3
The internal drainage of the mixed glaz-
porting structure, is used as an alternative to
the increased use of the combination of sin-
ing system works in the same way, with any
the extruded aluminium glazing bar, usually
gle layer membranes and rainscreen panels
water that penetrates the silicone sealed
for larger glass panels where the supporting
with capped and silicone sealed to provide
glazing being drained along the internal con-
fin or box profile to the aluminium extrusion
individual rooflights that are visually integrat-
densation channels before draining into the
would be visually too deep or too wide.
ed into adjacent areas of opaque roof. In (J),
profiles of the capped system and onwards down to the base of the roof.The condensation channel and inner air seal can also be
a single layer membrane roof is sealed into
Rooflights A useful application of combining
the edge of a capped glazed rooflight by clamping the membrane into the glazing sys-
formed in a single EPDM extrusion, as shown
capped and silicone sealed glazing is in
tem. In (J), a metal rainscreen is shown, com-
in (H), without the use of any aluminium
sealed rooflights, where strips or bands of
pletely independent of the rooflight, but set
extrusion, but with a supporting structure
glazing are combined with a roof in a differ-
onto the membrane to both protect it and
behind. In this case, the short lengths of pres-
ent material.Traditionally, individual rooflights
give a visual continuity to the rooflights
sure plate holding the glass in place are
are formed in upstands that sit high above
across the roof.
secured by self tapping screws that are
the level of the adjacent roof. Large numbers
secured to a supporting structure behind. A
of these traditional individual rooflights lack
a capped glazing profile, while the joints
hollow box section is shown in (H).The
the visual elegance of continuously glazed
within the rooflight, running across the
EPDM gasket, combined with a steel sup-
roofs. In recent years this has changed with
rooflight (at 90°), as shown in (H), use a sili-
MCR_ 76
The edge of the rooflight is formed with
Section 1:5. Horizontal panel to panel junction with capping 2 4
4
3
DG Bank, Berlin, Germany. Architect: Gehry
Cross section 1:10. Junction of 2 rooflights with opaque roof 2 2
2 4
9
3
3
Section 1:5. Edge of rooflight
Detail J
9
4
6
Detail K 2
9
4 10 10
3
cone-sealed profile to allow water to run
the rooflight where it is released above the
Details
down to the bottom edge of the rooflight
roof level of the adjacent membrane. Open-
1.
shown in (J).This lowest edge of the rooflight
able rooflights, as shown in the previous sec-
has a silicone sealed edge with a drip flashing
tion on capped glazing systems, can be incor-
glazed into the edge of the profile to drain
porated easily, with the use of an additional
water off the edge.The single layer mem-
sub frame, into which the openable light is
brane is tucked under this flashing and is
set.
clamped down with the pressure plate that extends the full width of the rooflight.The
Extruded aluminium glazing profile 2. Pressure plate and capping 3. Mild steel support frame 4. Double glazed unit with recessed edge 5. Insulated metal panel 6. Silicone seal 7. Glazing channel 8. Concrete base 9. Adjacent opaque roof 10. Rubber-based glazing profile
top edge of the rooflight (running parallel with the roof slope) has a capped profile to allow water to drain around the sides of the rooflight as shown in (K).The condensation channels in all profiles are set at the same level to ensure that any water that passes through the outer seal is drained through a set of linked channels to the bottom edge of
MCR_ 77
Glass 03 Bolt fixed glazing
Cross section1:10. Horizontal panel to panel junction 5
5
Detail V2
4
1
1
8
8
5
9 8
8
Hydrapier, Haarlemmermeer. Netherlands. Architect: Asymptote. 5
7
Section 1:10. Corner Detail V3
This method of glazing for roofs has been
being bolted directly to a supporting struc-
glazed roofs in mainly commercial and public
adapted from the technique used for glazed
ture without patch fittings at all.This further
buildings.
walls, where glass is fixed at points with spe-
enhances the essential concept of frameless
cially designed bolts rather than with a frame
glazing which is to provide greater visual
raised over the reliability of the waterproof
supporting the perimeter of the glass. Bolt
transparency than an equivalent framed sys-
silicone seals between glazed units, but these
fixed glazing for facade construction devel-
tem.
were soon overcome with a mixture of lab-
oped from patch plate glazing in the 1960's,
The patch plate method of frameless
During the early 1990's doubts were
oratory testing and a better understanding
where single glazed sheets of glass are bolted
glazing is not used very often in roofs, since
of the workmanship required with silicone
together with mild steel brackets. Glass fins
the glass fins become glass beams in such
jointing.While manufacturers offer propri-
are used to stiffen the glazed walls to replace
applications.While glass beams have been
etary systems for walls, which can include a
the aluminium mullions.The L-shaped patch
used in modest rooflight applications, there is
supporting structural system such as cable
fittings bolt the fins and glass together, as well
uncertainty surrounding the difficulty of
trusses, roof glazing systems are usually
as bolting the glass to the supporting struc-
replacing cracked or damaged beams once
designed for individual applications.
ture at the top and bottom of the wall.While
the roof is completed.This has limited the
this glazing method has been developed and
use of glass beams to modest applications in
is still in use, the idea of frameless glazing has
glass roofs. In contrast to this, bolt fixed glaz-
evolved further into double glazed units
ing has become increasingly popular for
MCR_ 78
Section1:50.Typical assembly
Detail V1
Plan1:10.Vertical panel to panel junction
Detail V4 5
3
3
3
2 9 3
8
3 5
Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.
3
Plan 1:50.Typical assembly
Mild steel connector Mild steel support frame Double glazed unit Silicone seal Bolt fixing Support bracket Concrete base Stainless steel cable Mild steel tension rod Mild steel plate Adjacent external wall
Plan1:10. Bolt fixing
3
3
8
8
8
5 5 1 3
3
Generic structural support methods
tilevered from the beam to support the
the edge of the glazed roof to form a tensile
edge of the panel above as well as one side
supporting structure like a tennis racquet.
of the panel next to it.This method provides
The cable trusses, always in tension, require
turally supported by either top hung or bot-
greater visual transparency than (A) but
an equivalent surrounding structure in com-
tom supported methods, the support of
requires larger brackets, which in practice
pression to transfer the loads to the main
glazed roofs is by trusses, steel sections or
detract little from the increased effect of
building structure.
purlins that span across the roof opening.
transparency.
Where glazed walls are usually struc-
For (nominally) flat roofs, the most common
The single tube section shown in the
Supporting brackets
arrangement of supporting beams is as
diagrams would suit only a short span, as in a
shown in (A) and (B). In (A) a supporting
rooflight, but large span roofs require deeper
brackets to which the bolt fixings are
beam is set under each glass joint, so that
beams, usually formed as open trusses in
attached. In the case of a short bracket
bolts are supported on each side of the
order to maintain the sense of transparency
attached to a beam, a mild steel bracket can
beam by a short bracket. In (B), only half the
at oblique viewing angles.Triangulated truss-
be welded to each side of the tube shown in
number of beams are required to support
es, as (C), provide both structure and sup-
(E). Because the bracket is welded, the
the same three panels of glass.This is
port for the glass, but tend to be visually
adjustment for tolerance between fixing of
achieved by setting the beam in the middle
heavy. Cable trusses, as (D), are often pre-
the supporting structure and the glass panels
of alternate glass panels. Brackets are can-
ferred, but they require a ring beam around
is taken out in the position shown in (E) at
All these supporting structures require
MCR_ 79
Glass 03 Bolt fixed glazing Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.
2
4
Mild steel connector Mild steel support frame Double glazed unit Silicone seal Bolt fixing Support bracket Concrete base Stainless steel cable Mild steel tension rod Mild steel plate Adjacent external wall
4
3
3
1
5
5 8
9
8
8
Section 1:10.Vertical panel to panel junction Section 1:10. Junction with adjacent roof
Section 1:10. Horizontal panel to panel junction
8
Elevation 1:100.Typical assembly
Detail W1
2
3
3
3
3
2
the connection between the bolt and the
either mild steel or aluminium.The casting
bracket. A slotted or oversized hole is cut
for this application would be made from a
into the supporting bracket and the bolt sup-
steel mould which is expensive to manufac-
method, the bolt fixing, is made typically in
porting the glass is fixed to it.The bolt may
ture, so a large quantity of cast brackets are
stainless steel, and consists of several com-
be off-centre from the bracket, and each bolt
needed to make this method economic.
ponents that form the complete assembly.
may be in a different position in relation to its
Adjustment is made in the same way as (F).
The part that passes through the glass has
neighbour.This can produce an awkward
In (H) the beam becomes a cable truss,
either a disc on each side of the glass to
appearance when seen from below the roof,
where a supporting bracket in either mild
clamp the glass or double glazed unit togeth-
but this is certainly one of the most econom-
steel plate or a casting is clamped to the
er, or alternatively is angled to form a coun-
ic solutions. In (F) a channel-shaped bracket is
cable. Here the adjustment for tolerance is
tersunk device within the depth of the dou-
welded to the top of the beam. A single
made in two places; at the junction of the
ble glazed unit.The countersunk fitting is set
bracket, typically mild steel plate, is bolted to
bracket and the bolt fixing, as well as at the
flush with the outer face of the glass, and the
the channel bracket. An oversize hole in the
junction of the bracket and the cable clamp.
face fixed disc type is set forward of the face
bracket is used to make the adjustment for
There are, of course, many variations on
of the glass. A polished stainless steel finish is
tolerance.The bolts supporting the glass are
these types, but these are the most com-
mostly used on the outside in order to make
set at each end of the bracket. In (G) the flat
monly used bracket support methods.
it easy to clean and maintain. In the face
bracket is replaced by a casting, usually in
MCR_ 80
Bolt fixings The essential component in this glazing
fixed type, which is currently the most com-
Section 1:10. Corner
Detail W4
Section 1:10. Horizontal panel to panel junction 4
4
5
1 5
5 5 2
2
4
8
8
Plan 1:10. Horizontal panel to panel junction at edge 8
Section 1:10.Vertical panel to panel junction
Detail W3
8 4
4
1
4
2
monly used fixing, the inner disc screws over
exposed, or be covered with threaded
increases dramatically with the increase of
the threaded shank that forms part of the
sleeves and stop ends, as shown in (J).This
thickness (the relationship between glass
outer disc until it is tight up to the inner face
bolt type is used regardless of the orienta-
thickness and cost is not linear).With bolt
of the glass.The threaded shank projecting
tion of the roof, whether flat or pitched.
fixings in these positions, the most economic
into the building is able to rotate about a ball bearing where it meets the inner face of the double glazed unit.This allows the double
position of support brackets is as shown in
Arrangement of bolt fixings The arrangement of brackets for bolt
(K). Flat plates can be used, subject to structural requirements.
glazed unit to rotate up to around 12°
fixed roofs is dependent upon the position
under wind load and associated structural
of the fixing bolts. In (K), rectangular shaped
tant from the edges of the glass as in (L), a
Where the glass fixing bolts are equidis-
deflections.This swivel joint is essential in
double glazed units are arranged with sup-
cross-shaped bracket allows four glass con-
avoiding the over stressing of the glass under
porting beams set in the direction of the
nections to be made with a single bolt con-
full wind load that would otherwise result in
long side of the panel. Bolts are positioned in
nection between this support bracket and
breakage of the glass unit.The threaded
a way that reduces the span of the glass by
the beam beneath.The cross-shaped bracket
shank is then used to clamp the complete
pushing them away from the edge.The
is carrying a high load of glass to a single
bolt fixing to a support bracket with either
reduced glass span allows the glass thickness
point on the beam. Stiffening fins are usually
threaded discs or nuts, as in (J).The visible
to be thinner, making it more economic, par-
needed on the underside of the cross-
thread in the shank can be either left
ticularly given that the material cost of glass
shaped bracket.These can be individually
MCR_ 81
Glass 03 Bolt fixed glazing 3
3 8 9
9
8
8
3
8
2
Section1:50.Typical assembly Section 1:10. Vertical panel to panel junction
Hydrapier, Haarlemmermeer. Netherlands. Architect: Asymptote.
3
4
2
8
welded and ground, but it is often economic
and adjusted to form even joint widths
support external sun shading and mainte-
to make them as castings, which have a more
between all the units. Joints of 20-28mm are
nance equipment.These brackets are usually
reliably refined appearance. Mild steel brack-
used, though around 20mm is the most
in the form of flat plates that are welded to
ets require painting; stainless steel brackets
common joint width (in elevation) that
the internal supporting structure, and pro-
can be buffed or polished to the preferred
allows for both structural movement and the
ject through the joint, as (M). Although an
visual finish.
slight variations in the size of the glass panels.
additional lip around the projecting plate
Unlike capped roof glazing systems, the
may provide additional protection to water
entire double glazed unit is visible from both
penetration between the silicone and the
outside and inside, and the edges are not set
bracket, in practice it has been found that
the inner glass of a double glazed unit is usu-
behind pressure plates that conceal any vari-
this detail as shown in (M) performs well if
ally made from laminated glass. In the event
ations in glass panel size. Joint widths up to
the seal is applied to a good level of work-
of a double glazed unit being broken, the
around 28mm, which is deemed close to the
manship.
inner laminated sheet remains intact, while
maximum practical joint width for the adhe-
the broken pieces of the heat strengthened
sion of silicone sealant in a regular double
made as an outer silicone seal with an inner
or fully toughened outer sheet come to rest
glazed unit, is used where brackets penetrate
backing rod of extruded EPDM.The gasket
on top of the damaged, but intact, inner
the outer seal from inside the roof to out-
has projecting flaps on each side to form a
sheet.The double glazed units are first fixed
side. If required, these brackets are used to
'fir tree' section which prevents any water
Glazed units In common with other glass roof types,
MCR_ 82
Seals between double glazed units are
Detail H Detail E
Detail F
Detail J
Detail G
Detail M
Detail K
Detail N
Detail L
Detail A
Detail B
Detail C
Detail D
that penetrates the external seal from reach-
Isometric view of roof assembly
The holes in double glazed units, to
ing the inner face of the seal.This EPDM gas-
which the bolt fixings are attached, are made
ket also serves as an inner air seal, and pro-
by cutting holes in the glass around 10mm
vides a crisp appearance of sharp lines in the
larger than the metal circular sleeve that fits
interior face of the glazed roof.
between it.The circular sleeve bonded to
In the manufacturing of double glazed
coatings, this is done after heat treatment.
the glass is sealed around it to maintain the
units, the butyl seal between the spacer and
sealed cavity of the double glazed unit.This is
Details
the glass creates a slightly wavy line, visible to
particularly important in the case of argon
the eye when it spreads beyond the face of
filled cavities, where the gas improves ther-
the spacer.This slightly uneven appearance of
mal insulation.
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.
the edge of the glazed unit can be concealed
The drilling of the glass itself is now well
by the use of edge 'fritting', or a baked-on
established in glass manufacturing, with both
screen printed edge in black, which ensures
float glass and laminated glass being drilled
that the edge of the unit, as shown in (N),
before any heat treatment to make them
has a crisp black edge.This is mainly where
either heat strengthened or fully toughened.
the rooflight glass can be seen at close prox-
Where coated glasses are used, such as solar
imity.
control coatings or low emissivity (low e)
Mild steel connector Mild steel support frame Double glazed unit Silicone seal Bolt fixing Support bracket Concrete base Stainless steel cable Mild steel tension rod Mild steel plate Adjacent external wall
MCR_ 83
Glass 04 Bolt fixed glazing : Pitched roofs and rooflights
Section 1:25. Panel to panel junction
2
2
Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.
2
Mild steel connector Mild steel support frame Double glazed unit Silicone seal Bolt fixing Support bracket Concrete base Stainless steel cable Mild steel tension rod Mild steel plate Adjacent external wall Plan 1:10. Panel to panel junction
5
2
4
Section 1:25.Typical assembly Section 1:10.Typical assembly 4
5
1
5
5
The generic support structures described in
visual consistency regardless of where the
welded, then an inner sleeve is inserted
the previous section suit a range of roofs in a
glazed roof is viewed below the roof.The
between the sections being jointed and the
single plane, whether pitched or (nominally)
ladder principle as shown in (P) is actually
edges of joints are welded together and
flat. Supporting structures which are facetted
two vierendeel trusses linked together, with
painted. An alternative fixing method is to
or curved to form complex geometries
the short cross members welded to the
bolt the sections together.This method
require a slightly different approach.These
long members. If additional stiffness is
avoids the bolts being visible, leaving only a
supporting structures are dictated more by
required in part or all of the structure, then
hairline joint visible at the junction, giving the
the demands of the form that is being creat-
cross bracing is typically added. Additional
joint a minimal appearance and avoiding
ed rather than by optimising the position of
structural stability is provided by folding,
welds which form a visible ring around the
supporting members to maximise visual
curving or ribbing the surface the surface of
joint.This joint method also allows a faster
transparency through the structure. Struc-
the structure, also as shown in (P).This
installation than if welding were used, with
tures for arches or curved surfaces are usual-
avoids the need to deepen the structure
the additional benefit that steelwork can be
ly made with as little structural depth as pos-
with trusses that significantly reduce the visu-
installed with a fully painted finish from the
sible, with the visually successful types using a
al transparency offered by bolt fixed roof
factory if required. In this method, a mild
single 'plane' of structure formed in 'ladder'
glazing.
steel plate is welded to each end of the tube
forms as shown in (P). Circular hollow sections and box sections are preferred for their
MCR_ 84
The 'ladders' are bolted or welded
being jointed. A rectangular hole is cut into a
together to form the complete structure. If
wall of one of the hollow steel sections, big
Section 1:75.Typical assembly
Conference Bubble, Lingotto Factory Conversion,Turin, Italy. Architect: Renzo Piano Building Workshop.
Plan 1:10. Junction with adjacent wall
Detail T4
2 11
4
Section 1:10. Base upstand
Detail S1 5 5
2
Plan 1:10. Junction with adjacent wall
Detail T3
2
5 4
7
Base of glazed roof
enough to pass a hand through. Accessing
a tubular supporting structure with mild
the inside of the hollow section from the
steel brackets fixed to the main tube (as
rectangular hole, bolts are fixed through the
described in the previous section).The posi-
rooflight, and a surrounding reinforced con-
end plates to fix the two steel sections
tions of the bolt fixing in relation to the edge
crete slab is shown in (S1), (S2) and (S3). An
together.The rectangular hole is then cov-
of the glass is optimised to reduce the glass
essential feature of junctions in bolt fixed
ered with a thin metal plate which is either
to an economic thickness. In (R), bolt fixings
glazed roofs at their perimeter is that there
bonded to the surrounding metal or is
are set mid distance between two horizontal
is no mechanical connection between the
screwed into the surrounding wall of the
ladders.This might correspond to a joint
double glazed unit and the adjacent roof
hollow section.
between two double glazed units or an addi-
deck, or parapet, since the glass is bolted
tional bolt fixing to secure a large double
some distance away from the corner, and
ly corresponds to the layout of the glass
glazed unit. A v-shaped mild steel bracket is
the edge of the glass is cantilevered from the
panels, since the corners of panels are fixed
set at 90° to the brackets in (Q).The stain-
bolt fixing.The adjacent roof or external wall
back to the supporting structure, which is
less steel bolts are aligned in elevation with
(in a different material) meets it with two
preferably as close to the glass joints (in ele-
adjacent brackets in (Q).
sets of silicone seals only, or alternatively
The structural form of the 'ladder' usual-
Junctions of the bolt fixed glazed roof, or
vation) as possible. In (Q) and (R) the struc-
with EPDM seals which are bonded to the
ture is set in line with the joints in the glass.
edge of the glass unit. In (S3), a low pitched
In (Q) the bolt fixings for the glass is fixed to
roof meets a reinforced concrete upstand
MCR_ 85
Glass 04 Bolt fixed glazing : Pitched roofs and rooflights Elevation 1:10. Internal fold
Details
5
1. 2.
10
3
3
Mild steel connector Mild steel support frame 3. Double glazed unit 4. Silicone seal 5. Bolt fixing 6. Support bracket 7. Concrete base 8. Stainless steel cable 9. Mild steel tension rod 10. Mild steel plate 11. Adjacent external wall
1
1
4
4
5
3
2
3
Plan 1:100. Penetration of plate through glass joint Section 1:10. Base upstand
5 4
Detail S2
5
3 5
2
1
3 5
5
4
2
1
7
2
Sections 1:10. Internal fold
Detail T2
forming part of a concrete roof deck.The
up the face of the upstand across the top.
supporting steel structure is fixed to the
This combination provides an inner, second
edge of the concrete slab, which typically
line of defence to the flashing above.The
forms a continuous ring beam around the
outer flashing is set on the outer face of the
opening to carry the load of the glazed roof.
glass, and has a folded edge in order to bond
that form ridges and valleys are formed as
The base of the glazing has a cantilevered
it with a silicone seal, typically 20mm wide to
external folds and internal folds respectively.
edge of the double glazed unit which is
match visually with the other seals between
While the joint is formed in the same way as
sealed to an aluminium flashing. An additional
the glass units. Any rainwater which pene-
other joints, with an outer silicone seal and
flashing, which is continuous with the water-
trates the outer seal is drained away on the
an inner extruded EPDM baffle, or air seal,
proofing membrane, is set on the inside face
inner metal flashing onto the waterproof
the double glazed units are stepped on their
of the glass.This folded aluminium strip is
membrane.The void between the two flash-
edges to ensure that the joint is not wider
bonded with silicone to the bottom of the
ings is filled with closed cell thermal insula-
than adjacent joints, as in (T1) and (T2).
double glazed unit. It can be either concealed
tion, sometimes as injected foam to fill the
With an external fold the outer glass is
by the interior finishes or be coated, usually
cavity completely.Variations of this principle
stepped beyond the edge of the unit to
in a PVDF or polyester powder coated finish.
are shown in (S1) and (S2). In (S1) an all-
maintain a constant width through the depth
This aluminium strip is bonded to the edge
metal upstand flashing is used, while in (S2)
of the joint, as (T1), while in (T2) the internal
of the waterproofing membrane that extends
the upstand is concealed by an accessible
fold has the inner laminated glass extending
MCR_ 86
timber deck.
External and internal folds Changes of direction in bolt fixed roofs
Plan 1:100. Concealed framing connection
Section 1:10. External fold
Detail T1
4
10
5 10 3
Plan 1:100.Typical glass fixing arrangements
3
Detail R
2
Elevation 1:10. External fold
Plan 1:100.Typical glass fixing arrangements
5
Detail Q 4
1
1 4
3
3 5
beyond the outer glass to perform the same function.The joint width both externally and
external wall clad in terracotta panels. Support brackets for external shading
Small glazed rooflights An essential aspect of small rooflights is
internally is made to match the width of
and for rope fixing points for abseil-based
the greater number of interfaces with sur-
adjacent joints in order to allow the same
cleaning are sometimes designed to pene-
rounding construction and other materials
extruded EPDM gasket to be used as an
trate through the joints between the glass
than is usually the case with large glazed
inner seal.
joints.This method is described in the previ-
roofs.Where small rooflights have a bolt
Junctions of the edge of the roof with
ous section.Where these brackets occur at
fixed glazing assembly mixed with gutter ele-
external walls in other materials as (T3) and
external and internal folds, the brackets are
ments in a typical single rooflight, as (U), the
(T4) are similar to flashings at the base of
usually designed so as to avoid penetrating
glazing is sealed against the adjacent con-
the roofs, as (S3), with which these joints can
the joint at the corner itself.This is done to
struction. In (U) an outer seal is formed
be continuous as the roof perimeter turns
avoid a complicated junction of the bracket
against an external roof panel in a different
from roof to external wall. In (T3), an insulat-
together with the four corners of a joint
panel. A second inner seal is made with an
ed aluminium closer is bonded to the edge
meeting at the same place.This is both diffi-
inner metal panel. Glazing channels can also
of the double glazed unit and is sealed
cult to seal and difficult to give a smooth,
be used (as described in the previous sec-
against the adjacent wall construction. In
continuous appearance as seen from inside
tion) in order to seal the gap but the glazing
(T3) the roof meets a metal rainscreen wall,
the building.
channel must be connected to a flexible seal
while in (T4) a bolt fixed roof meets an
such as an EPDM strip to allow the bolt
MCR_ 87
Glass 04 Bolt fixed glazing : Pitched roofs and rooflights
Section 1:10. Junction with another material
3
5
Section 1:10. Base upstand junction Detail U 5
Isometric view of roof assembly
3
Detail P
2
Conference Bubble, Lingotto Factory Conversion,Turin, Italy. Architect: Renzo Piano Building Workshop.
7
fixed glazing to move independently of the
bolt fixings are secured to a cross-shaped
ners of meeting double glazed units in bolt
other materials making the junction. In (U) it
bracket which is in turn bolted to two halves
fixed roofs have a wide sight line, the conti-
is assumed that these structural movements
of a clamp bolted to the supporting cables.
nuity of the glass and its reflections obscure
are small.
A vertical mild steel rod forms the central
the effect of the fritting and silicone seals
In small rooflights the supporting struc-
vertical element in the truss, as shown in
behind.
ture is made visually lightweight in order to
(V2).The absence of steel tubes spanning
maximise the effect of the bolt fixed glazing.
across the centre of the top of the rooflight
Stainless steel cables are often used to
increases its visual transparency. Junctions at
increase transparency. In (V1), a small
the corner and at the base of this typical
metres high and 8.0 metres wide, lightweight
rooflight of 3500mm x 3500mm in plan is
small rooflight as shown in (V3). In plan in
hollow mild steel sections, together with
made from a mild steel tube supporting
(V4), external corners are formed by step-
stainless steel cables are commonly used.
structure.The top of the rooflight requires
ping the edges of the double glazed unit in
This rooflight size suits glass sizes which are
four glass panels in order to span from side
order to maintain a constant joint width for
around 2000mm x 2000mm for horizontal-
to side.The bolt fixings in the centre of the
all rooflight joints.The visible area of silicone
ly-set units and around 2000mm x 2500mm
top of the rooflight are supported by two
behind the glass can be concealed with silk
high for vertically-set units. A modest rectan-
cable trusses spanning diagonally from the
screen printing, or 'fritting', usually in a black
gular steel frame forming the edges of the
corners, intersecting in the centre.The four
colour. Although external and internal cor-
generic rooflight shown in (W1) and (W2)
MCR_ 88
Larger rooflights For bigger rooflights up to around 5.0
Section 1:10. Bracket support
2
5
5
5
3
3
5
Long section 1:10. Base upstand
3
4
4
Detail S3
Section 1:10. Bracket support 5
3 3
3
2
4
Section 1:10. Bracket support
2
7
3
can support stainless steel cables spanning
greater visual transparency than the all-tube
both vertically and horizontally to which bolt
solution.The main stainless steel cables of
fixings and cross-shaped brackets can be
the truss span across the diagonal corners,
fixed.The cross-shaped bracket is fixed to a
meeting at a central vertical tubular post, as
clamp which is bolted to the cable, as in
described in the previous paragraph for
(W3). For glass joints set directly in front of
small rooflights.The increased span is assist-
the tubular steel structure, the bolt fixings
ed by a set of secondary steel cable trusses
are secured directly to a channel-shaped
set at 45° to the diagonal geometry
bracket welded to the main supporting steel
(orthogonal with the glass), as shown in
tube, as in (W4). All bolt fixings in these
(W2).The secondary trusses both stiffen the
modest sized rooflights have their adjust-
main trusses and provide a fixing point for all
ment for fixing tolerance made at the junc-
bolt fixings.The principle of this medium size
tion of the bolt fixing and the support brack-
generic rooflight can be adapted to suit a
et.The glass units set horizontally can be
range of individual designs of similar overall
supported at their corner fixings by either a
dimensions.
grid of steel tubes immediately below the
4
3
Details 1. 2. 3. 4. 5. 6. 7.
Mild steel connector Mild steel support frame Double glazed unit Silicone seal Bolt fixing Support bracket Concrete base
8. 9.
Stainless steel cable Mild steel tension rod 10. Mild steel plate 11. Adjacent external wall
joint, or with a cable truss, which provides
MCR_ 89
Glass 05 Bolt fixed glazing :Twin wall roofs
8
2
8
5
5
3
8
4
1
4 3
2
Elevation 1:25.Typical assembly
Bolt fixed glazing can be used as solar shading in twin wall rooflights.Two generic examples are shown here for a square-shaped rooflight and a circular-shaped rooflight, both of a
8
medium size.The square example is 8.0 2
metres x 8.0 metres for the inner glass roof, and the circular rooflight has a radius of 9.0 metres across its inner glazing. Both use the same structural principle of a tubular steel frame with stainless steel cables stretched between them, but the position of the structure in relation to the bolt fixed glazing is different for each rooflight.These examples aim to show a visually lightweight solution that
Section 1:25.Typical assembly
suits the quality of visually transparency that can be achieved with bolt fixed glazed roofs rather than more conventional framed solu-
MCR_ 90
Section 1:25.Typical assembly
Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.
Mild steel connector Mild steel support frame Double glazed unit Silicone seal Bolt fixing Support bracket Concrete base Stainless steel cable Mild steel tension rod Mild steel plate Adjacent external wall
8
2
8 3
3
Plan 1:25.Typical assembly
3
2
4
8
8
tions that detract from the thin joint lines of this roof glazing method. Both examples have an inner sealed rooflight and an outer layer of open jointed glass solar shading pan-
3
3
els.The outer glass can be either screen printed with dots or patterns to provide shading, or have a solar control film set next to the PVB interlayer within the laminated glass.The inner glass in each example comprises sealed double glazed units. A crossshaped support bracket has been used in each rooflight, and the glazed units are square shaped to keep the examples as generic as possible. The square rooflight has two rectangular frames, one set inside the other, linked by diagonal members.The inner roof is hung
MCR_ 91
Glass 05 Bolt fixed glazing :Twin wall roofs 12
2
12
8
8
3
3
3
3
3
3
8
Details
12
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.
8
3
3
Mild steel connector Mild steel support frame Double glazed unit Silicone seal Bolt fixing Support bracket Concrete base Stainless steel cable Mild steel tension rod Mild steel plate Adjacent external wall Single glazed solar shading glass
3
7
2 11
Section 1:80.Typical assembly
2
3
3
3
2
12
Plan 1:80.Typical assembly
MCR_ 92
2
12
12
Part plan 1:80.Typical assembly
3
3
3
3
12
12
Elevation 1:80.Typical assembly
12
12 2
12 3
3
3 2
3
3
3 3
7
Section 1:80.Typical assembly
12 12
12
12 2
2
12
12 8
3
2 12 2
3
3
7
11
Key plan 1:200.Typical assembly
MCR_ 93
Glass 05 Bolt fixed glazing :Twin wall roofs 3
3
8
Plan 1:25. Penetration of primary structure fixing bracket through joints bewteen glass panels.
2
3
3
8
4
3
3 4
2
Elevation 1:25.Typical assembly
from steel cables which span from side to 2 3
side in both directions, forming a rectilinear grid of cables. Cross-shaped bolt fixing brackets are set at the intersection of these cables.The vertical parts of the inner sealed rooflights are set out in the same way, so that the supporting structure is entirely outside the building.The external sun shading is
3
fixed in the same way, but with the outer glass fixed above the supporting cables.The rooflight has solar shading on its roof and on three vertical sides, so that from outside the
Section 1:25.Typical assembly
building the supporting structure is seen only through the shading.The outer shading is tilted out of plane in relation to the inner cube. With this construction method the inner and outer cable structures do not need to
MCR_ 94
Plan 1:25.Typical assembly
Section 1:25.Typical assembly 3
11
3
Section 1:25.Typical assembly
Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.
Elevation 1:25.Typical assembly
3
Mild steel connector Mild steel support frame Double glazed unit Silicone seal Bolt fixing Support bracket Concrete base Stainless steel cable Mild steel tension rod Mild steel plate Adjacent external wall
2 3 8 8 9
2
2
3
follow the same geometry. The circular rooflight has an outer shad-
top of the glass is cleaned by passing the rope of the person's harness through the
ing set on top of the inner sealed rooflight
open joints between the glass shading
to provide partial solar shading.Where the
panels.The gap is 20mm-25mm which is
square rooflight has a gap of approximately
sufficient for a rope and securing hook.
1.0 metres between the two skins of glass to
The use of bolt fixings instead of a
provide maintenance access for cleaning, the
framed rooflight system allows the glass
circular rooflight has a gap of only 600mm
panels to experience deflections under
around its edge.Where there is not sufficient
wind load that are higher than those per-
space for a 600mm to 1000mm gap for
missible in a rigid, framed system.This
maintenance access, a structural tube is
allows a single line of cables to be used,
removed when access is required.
where they would have to be formed into
Cleaning and maintenance is undertaken on both rooflights by walking on the glass
(more rigid) trusses if a framed system were used.
itself, with individuals wearing harnesses which are secured to the upper cables, which also serve as a fall arrest cable.The
MCR_ 95
Glass 06 Bonded glass rooflights Section 1:25.Typical assembly Type A
6
6
3
Section 1:5. Junction with adjacent material
1
3
Section 1:5. Glass to glass junction
3
3
Section 1:5. Junction with upstand Key plan
3
3 3
5
The method of silicone bonding glass to alu-
minium frame. Silicone bonding avoids cover
minium framing is well developed for use in
caps which would have to be curved both
In (A) a lightweight steel frame is used
glazed curtain walling to provide visually
vertically and horizontally, which would be
to support double glazed units that form a
smooth glass facades with no visible cappings.
extremely difficult to fabricate. In (B) a
rooflight.The structural frame comprises box
The use of silicone sealed rooflights, dis-
rooflight is bonded together without a sup-
sections set vertically, held in place by thin
cussed in an earlier section, can be taken a
porting structure; the glass provides its own
tube sections running horizontally to form a
step further to become a full bond without
support. In (C) a flat monopitch rooflight is
circle.The glass panels are supported on
the need for the mechanical restraint of pres-
bonded to a frame to provide a small
steel flat sections which are welded to the
sure plates. In silicone bonded rooflights, the
rooflight from one double glazed rooflight. In
horizontally set tube section, as (E).The glass
glass is glued to a supporting frame.The glue
(D) laminated glass sheets are used to form
is levelled on blocks set onto the horizontal
is also the external seal.This technique is use-
a glass roof which can be walked upon. Simi-
flat section, and the silicone is applied to the
ful for small rooflights, where cappings would
lar to a glass floor used inside a building, it
joint. At the base, the horizontal metal sec-
be very difficult to fabricate, and in rooflights
must also take heavier traffic loadings and be
tion projects out to form a flashing over the
which are walked upon, where the rooflight
weathertight.
upstand in which the rooflight is set. An addi-
is an external glass floor. In (A) a generic conical rooflight has curved double glazed units bonded to an alu-
MCR_ 96
Generic conical rooflight
tional inner metal upstand can be provided with another silicone seal if there is risk of future flooding from blocked rainwater out-
Section 1:10.Base upstand. Junction with adjacent material.
Details 1. 2. 3. 4. 5. 6. 7. 8.
Silicone bond Mild steel support frame Single glazed laminated glass panel Silicone seal Concrete base Insulated metal panel Folded metal flashing Reinforced concrete support frame
Detail F
Plans 1:5. Glass to glass junction 3
3
4
6 2
4 3
3
3
3
2
2
Detail E 3
Pavilion, London. Architect:Toyo Ito & Associates
7
5
lets, for example. In (E) the waterproof
with the double glazed unit, as shown in (F).
the corners, but this additional safety feature
membrane for the roof slab is continued up
The fold forms an edge to make a silicone
is dependent upon the individual rooflight
the upstand and is bonded to the base of
seal.The glass is bonded to another steel flat
design and the local building codes.
the horizontal section that supports the
set below the metal cover.This provides lat-
glass.This provides a complete seal from the
eral support to the glass unit as well as mak-
glass to the roof membrane, with the metal
ing an additional inner seal.The metal cover
flashing providing both a protection to this
is typically formed from a single piece of alu-
a supporting frame. Mechanical restraint is
seal and a means of concealing the closed
minium or stainless steel that is welded and
provided at the corners in the form of pres-
cell thermal insulation set on top of the
ground smooth, and is insulated with inject-
sure plate clips.The double glazed units at
waterproof membrane.
ed foam or mineral fibre quilt to provide a
the corners are fabricated with a recessed
continuity of thermal insulation.
groove on the two sides of the panel form-
At the top of the rooflight, a metal panel is used to seal the pointed form.The glass
The use of silicone bonding in this
Generic rectangular rooflight In (B) a rooflight is constructed without
ing the corner in order to receive the clip.
can be continued almost to the top, with
rooflight avoids the need to use visually
An alternative method is to fix the metal clip
only a small pointed metal cover, but this
obtrusive bolt fixings, allowing the form of
to the outside of the glass at the corner.This
example aims to show how the glass is
the rooflight to be seen more clearly. In
avoids the need for specially made corner
sealed to another material set above it.The
some countries, additional restraining clips
pieces but it does form a visible fixing.The
metal cover is folded inwards at its junction
are required on the outside of the glass, at
modest size of this rooflight allows the hori-
MCR_ 97
Glass 06 Bonded glass rooflights
Section 1:5.Typical assembly
Detail G
7 4
3
3
3
3
2 3
3
3 2 7
5
Section 1:5.Typical assembly
5
Plan 1:5.Typical assembly 7
3
3
Plan, Section, Elevation 1:25.Typical assembly
Type B
Plan 1:5. Typical assembly
zontally-set glass to span from side to side
brackets to the required height of the flash-
insulation can be difficult to install in such sit-
with no additional support.The corners of
ing.These metal brackets are fixed to the
uations, the continuity of insulation is essen-
the rooflight are stiffened by short lengths of
adjacent roof deck. A concrete upstand is
tial to avoid the effects of thermal bridging.
pressure plate which hold the glass in place.
shown in (G).The waterproof membrane for
The glass has a specially shaped groove in the
the adjacent roof extends up the upstand
at its base is bonded to an inner metal angle.
depth of the double glazed unit, to which the
and up the face of a folded aluminium sheet
The outside face of the glass is sealed to the
pressure plates are fixed. Corner joints have
that forms a complete weathertight seal.
metal flashing below with silicone. Any water
an outer corner piece of folded aluminium
Closed cell thermal insulation is applied to
that passes through the outer seal is drained
which is silicone bonded either to the face of
the outside of this membrane, and an outer
to the external face of the roof membrane
the adjacent glass units, or is folded at 90° to
pressed aluminium flashing is fixed to protect
beneath.
bond it to the side of the unit. Glass-to-glass
both the membrane and the thermal insula-
Small rooflights can have upstands as
joints between horizontally-set units have a
tion.The insulation forms a continuous layer
flashings which can appear to be large in
silicone seal with an aluminium angle set on
from the junction with the roof insulation up
relation to the area of glass. In highly visible
the inside face to provide a second seal.
to the silicone seal in order to avoid any
or accessible roofs this can be avoided either
The inside face of the double glazed unit
At the base of the rooflight the glass
thermal bridges that would cause condensa-
by setting the rooflight on the outer edge of
units are seated on aluminium or mild steel
tion to form on the inside face of the fram-
the upstand to create a flat appearance to
sections which are in turn supported on
ing in temperate climates. Although thermal
the flashing, or by adding a layer of decking
MCR_ 98
Key plan 1:25.Typical assembly Type C
Section 1:5.Typical assembly
Details 1. 2. 3.
Silicone bond Mild steel support frame Single glazed laminated glass panel Silicone seal Concrete base Insulated metal panel Folded metal flashing Reinforced concrete support frame
4. 5. 6. 7. 8.
3
7
7
3
3
7
3
5
5
Section 1:25.Typical assembly
to conceal the upstand. Decking is usually in
between glass and frame is then sealed with
nal decks, manufactured as proprietary sys-
the form of open jointed concrete slabs or
silicone using a polymer backing rod.The sur-
tems. Single glazing is used, since double
timber boards.
rounding waterproof membrane is lapped
glazed units are difficult to use as a result of
up the edge of the vertical ring to provide a
solar gain around the edge of the unit,
continuous seal around the rooflight. Detail
where the glass is exposed to the outside,
(G) shows a metal panel forming the edge
but is supported on its underside, allowing
visually simple method of closing a roof
of the silicone seal around the glass.The con-
heat to enter but not to escape.Where
opening formed in a different material.The
tinuity of thermal insulation is provided by
black coloured edge 'fritting' is used, the situ-
circular rooflight is formed by a circular ring
closed cell insulation set onto the roof mem-
ation is made difficult. However, double
of aluminium fixed on Z-shaped brackets
brane that extends up to the silicone seal.
glazed roof decking is in development and
Generic monopitch rooflight The monopitch rooflight (C) provides a
will no doubt become much more common
which are fixed to the concrete upstand beneath. A vertical metal flat section is
Glass roof decks
over the next 10 years. The glass used is laminated, in common
screwed to the Z-sections and the junction
Rooflights formed as (nominally) flat,
with the flat ring is sealed with silicone.The
accessible roof decks have been in use over
with other rooflights, both to avoid the pos-
circular double glazed unit is set into this ring
the past 10 years. Previously used only inside
sibility of any falling objects from penetrating
frame in a bed of silicone with spacer blocks
buildings for walkways and stairs, they are
the glass on impact, as well as preventing
to locate it evenly on the ring.The joint
now being used as fully waterproofed exter-
damaged glass from falling immediately into
MCR_ 99
Glass 06 Bonded glass rooflights
Detail L
Type D 3 4
4
1
3
1
2 2
2
2
5 10 10
9
Key Plan :Typical assembly.
Detail H
Detail K 3
3
Detail J
3
2
Details for glass deck 2
8
1. 2. 3. 4. 5. 6.
Silicone bond Structural glass beam Single glazed laminated glass panel Silicone seal Concrete base Insulated metal panel
the space below.The glass is set into a series
depending upon the individual design.The
glass beams are supported by a metal shoe
of extruded aluminium angles to which it is
glass beams here comprise three layers of
support, made from either mild steel or alu-
bonded on its underside. A gap between the
glass, each 19mm thick, which are laminated
minium as (L). Stainless steel is used where
frame and the top of the glass is sealed with
together. In the event of one glass being bro-
corrosion is an essential consideration of the
silicone of a different type. An additional con-
ken, the remaining two glasses will take the
design.The metal shoe is bolted back to the
densation channel is set below the glass to
full load, avoiding collapse of the beam.The
supporting structure or reinforced concrete
catch any water that penetrates the silicone
overall thickness of the beam, of approxi-
floor slab.The gap between the edge of the
seal, or any water that passes through a dam-
mately 60mm, also provides sufficient bear-
glass deck and the adjacent roof finish mate-
aged joint.
ing for the two glass sheets that meet on
rial is made with a silicone seal as shown in
top, as shown in (J). Each glass has 20-25mm
(L).
The details here show alternatives for both steel beam and glass beam supports to
bearing, with a 15-20mm joint width
the glass panels. Detail H shows a typical
between the glass decking sheets, to suit the
1000mm x 1000mm to 1500mm x
rooflight with glass panels 2400mm x
individual design.Where steel plate is used
1500mm. Both panel size and overall glass
1200mm in size.The supporting structure has
to provide a beam instead of laminated glass,
thickness are determinants in the overall
a glass beam set in the centre, spanning the
as (K), a steel flat is welded to the top of the
rigidity of the glass deck and its associations
full length of 6000mm. Its depth is approxi-
beam to form a T-section that gives enough
vertical deflections.Typical vertical deflec-
mately 600mm, but the beam depth will vary
bearing for the glass deck.The ends of the
tions for the glass build-ups, given below,
MCR_ 100
Typical glass deck panel sizes range from
Section, plan 1:25.Typical assembly 3
3
2 5
2
5
7. 8.
Folded metal flashing Mild steel plate beam as alternative support 9. Folded aluminium decorative cover 10. Steel aluminium support ‘shoe’ 3
Pavilion, London. Architect:Toyo Ito & Associates
5
3
range from 0.2mm to 2.0mm, though the
steel cleats in the manner of steel framed
glass, which has the added benefit of reduc-
acceptable amount of vertical deflection
floor construction. Both methods require at
ing visibility through the glass from below.
under full design load is dependent upon the
least one of the glass beams to be drilled in
specific design application.Typical laminated
order to bolt the metal component to the
glass build-ups for the range of panel sizes
beam.When bolting a glass beam to a steel
just mentioned are as follows.The thickness-
beam, as in (K), the same principles apply of
es of interlayers have been ignored for clari-
using a metal shoe.The drilling of glass is a
ty:
well established technique developed mainly for bolt fixed glazing. 15mm+12mm+12mm = 39mm thick
Glass decks usually have an additional
15mm+15mm+12mm = 42mm thick
layer applied to the top surface of the glass
15mm+15mm+15mm = 45mm thick
to increase its friction which reduces the possibility of a building user from slipping
At the junction of glass beams, the sec-
while walking on the glass. Carborundum is
ondary glass beam is fixed to the primary
sometimes added to the top surface of the
beam by either a mild steel shoe, in the
glass for this reason. An alternative method is
manner of timber floor construction, or mild
to 'frit' or screen print the top surface of the
MCR_ 101
Glass 07 Glazed canopies
8
7
2
2 6
Plan, section 1:25.Typical assembly
Example A
6
6
6
2
2
Details
Section 1:10. Bolt fixing details
1. 6
3
3
3 1
1
2
1 2
2. 3. 4. 5. 6. 7. 8.
Cast mild steel or stainless steel angle bracket Single glazed panel Mild steel or aluminium tube Support bracket Bolt fixing Steel strut secured to primary structure External wall Building structure
An essential development in glazed canopies
the side of a flat roofed building, that might
between glass and supporting structure, can
has been in the use of frameless glazing tech-
be one or two storeys high.The tubular
be controlled much more carefully in small-
niques to create an effect of increased trans-
metal structure shown can be fabricated in
er-scale canopy construction.
parency, where the glass surface and its
both steel and aluminium. Because of the
reflective qualities are visually stronger than
relative small scale of the construction, the
comprises horizontally-set tubes fixed at one
the supporting structure and the visual
canopy frame can be built to very close fix-
end to the building structure.The other end
rhythm of the glazing bars. In framed glazing
ing tolerances in relation to the glass, allow-
is supported by a diagonally-set rod hung at
canopies, particularly those of traditional
ing the bolt fixings to be secured without
an angle of 30°, the rod being fixed at its
design, the framing is more visually dominant.
the usual slotted connections used in bolt
upper end back to the building structure.
Both bolt fixed glazing and clamped glazing
fixed glazed wall or glazed roof construction.
The horizontally-set tube is fixed to the diag-
techniques are used, with bolt fixed glazing
This gives a visually refined appearance, with
onally-set rod with a pin connection, typically
using in frameless glazing, typically, a support-
the curved support arm for the bolt fixing
a 12mm diameter bolt, for this scale of con-
ing steel frame, and clamped glazing using
being fixed directly to the supporting struc-
struction. A rod is used rather than a cable,
laminated glass beams as a supporting struc-
ture with a precisely positioned threaded
since the glass canopy is required to with-
ture fixed with stainless steel clamps.
hole.This use of high levels of fixing preci-
stand wind loads which are both positive
sion, which is much more difficult in large
and negative, that is, for both downdrafts
assemblies due to the difference in position
and updrafts of wind.The visible bolt con-
The bolt fixed example shown in generic example (A) shows a glazed canopy fixed to
MCR_ 102
In generic example (A) the metal frame
Plans 1:5. Connection at top of strut
Plan 1:10.Typical glass panel
8
7 8
5
5
2 7
6 6
Train Station, Heilbronn, Germany. Architect: Auer und Weber / Schlaich Bergermann und Partner 2
9. Extruded aluminium glazing bar 10. Single glazed sheet 11. Aluminium pressure plate and capping 12. Insulated metal panel 13. Silicone sealed joint 14. Silicone bond 15. Single glazed panel 16. Silicone seal 17. Laminated glass beam 18. Steel connector rod secured to primary structure
5
nections for the supporting structure to the glass are typically dome head, flat head, or of
the slotted hole junction. In common with the inner glass of over-
2
5
also be coloured or patterned by a screen printed process in order to provide solar
specially machined shape, as shown in the
head glazed rooflights, laminated glass is used
shading, or simply a degree of opacity in
drawn example.These types are visually
in order that the glass will hold together as a
order to conceal dust that would accumu-
more refined than the traditional hex head
single piece if broken, typically as a result of
late on top of the glass.The canopy as
type, which leaves the thread of the bolt
an object falling onto the canopy from
shown in (A) drains forward and discharges
exposed on one side.The small dimensional
above.The glass is made sufficiently thick to
water over its front edge. A more typical
tolerances needed both during construction
avoid any visual deflection along the front
canopy design would slope back to the
as well as to accommodate structural move-
edge of the glass, which could otherwise
building and drain into a gutter that is either
ment are provided by oversize holes in the
result in a very 'wavy' appearance from glass
visible or is concealed within the facade.
glass.The slight difference in alignment
sheet to glass sheet along the length of the
between hole and bolt fixing is concealed by
canopy. Even if the safety criteria is met, the
first attached to the glass using the method
the disc-type fixing in the drawing. Counter-
deflection of the glass under its own weight
described in the first section on bolt fixed
sunk fixings are also used but this results in
usually becomes the deciding factor in deter-
glazing in this chapter.The bolt fixing has a
the fixing tolerance being moved back to the
mining glass thickness, which may be greater
ball bearing joint inside the assembly which
junction between the bolt fixing and the sup-
than that required for safety in order to
allows it to swivel up to around 12° in order
port bracket to which it is fixed, resulting in
achieve a crisp, straight edge.The glass may
to accommodate structural movement in
In the generic example, each bolt fixing is
MCR_ 103
Glass 07 Glazed canopies
3
3
7
Plan 1:5. Bolt fixing details
Section 1:5. Bolt fixing details
Section 1:5. Bolt fixing details 6
8
3
3
1
5
5
7 2 2
the supporting frame.The threaded shank of
welded tubes is in painted mild steel and
laminated glass used, but the glass thickness
the bolt fixing is then fixed to the connector,
that the curved support arm is of polished
is determined for each application.
which is shown as a cast steel bracket. Cast-
stainless steel.The bolt fixing is made from
ings usually require some buffing after manu-
polished stainless steel as is usually the case
is to clamp the glass sheets together as
facture to remove the rough edges and
for all glazed roofs and glazed walls that use
shown in the photographs of a canopy at
uneven pitting as a result of the sand casting
this technique. A separating pad, such as a
Heilbronn Train Station in Germany by Auer
method normally used.When a semi-smooth
nylon washer, is set between the stainless
und Weber / Schlaich Bergermann.The
finish is attempted, the results usually look
steel bracket and the mild steel frame to
glazed is clamped using a technique similar
very uneven. As a result, bolt fixing castings
avoid corrosion between the two metals.
that used for glazed walls (as described in
are either lightly buffed, or fully polished. If
The bolt securing the arm to the supporting
Modern Construction Facades).The glass
mild steel is used, the casting is usually buffed
frame is also made from stainless steel.This
sheets are bolted together with disc-shaped
smooth, then painted. If stainless steel is used,
combination of materials gives a visual con-
clamps set in the joints between the glass. In
the casting either has a light buff or is pol-
trast between the two types of metal, but
this example the discs are set at the inter-
ished to either a brushed finish, which is not
the choice of materials, other than for the
section of four panels, but this reduces the
very reflective, or a fully polished finish, which
bolt fixing itself, is a matter of individual
size of each glass panel that can be used
is highly reflective. In the generic example, it
design.The glass size here is 1500mm x
when compared to placing the fixing away
is assumed that the supporting frame of
1500mm, with approximately 12mm thick
from the corners. By fixing the clamps on all
MCR_ 104
An alternative to drilling the glass sheets
Details 1. 2. 3. 4. 5. 6.
4
7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18.
6 7
4
Cast mild steel or stainless steel angle bracket Single glazed panel Mild steel or aluminium tube Support bracket Bolt fixing Steel strut secured to primary structure External wall Building structure Extruded aluminium glazing bar Single glazed sheet Aluminium pressure plate and capping Insulated metal panel Silicone sealed joint Silicone bond Single glazed panel Silicone seal Laminated glass beam Steel connector rod secured to primary structure
3
8
2 5
5
Cross section 1:10.Typical assembly Long section 1:10.Typical assembly
3
1
1 2 5
four sides, away from the corners, the distance between clamps is the same, but this
Four edge restrained canopy An alternative to the bolt fixed method
5
edge of the canopy to avoid a sheet of rainwater falling onto building users passing
allows larger panels to be used. In this exam-
is to use the more established method of
underneath, but the ends of the gutter are
ple, the glass clamps are hung from a cable
glazing bars which capture the glass with
open, serving as water spouts that freely dis-
structure which is secured to a tubular mild
pressure plates using the technique
charge the rainwater to the ground below.
steel supporting frame. Because the glass is
described in the second section of this chap-
This avoids the need for rainwater pipes that
fixed at the corners rather than away from
ter. Glazing bars with pressure plates and
often do not suit the visual qualities of
the edges, as used in the bolted fixed canopy
cover caps are set in the direction down the
glazed canopies.
example, the distance between fixings
slope of the roof, while joints running across
increases, which usually makes the glass
the slope of the roof have silicone seals
generic example (B) is 1700mm wide x
thickness greater for the clamped solution
which are flush with the top surface of the
1000mm long in 12mm thick glass. As with
than that which would be required for the
glass in order to allow rainwater to run
all these examples of glazed canopy, the glass
bolt fixed solution. But this increase in mate-
down the roof.The rainwater is allowed to
sizes are for indicative purposes only, and are
rial cost is compensated by the saving made
discharge freely from the roof and is termi-
calculated for each application. In (B) the top
in not having to drill the glass to receive the
nated without a gutter at its lowest point
of the glazing is terminated in an insulated
bolt fixings.
depending on the size of the glass. Some-
metal panel which is sealed by a flashing to
times a gutter is provided along the bottom
the external wall above. It is assumed that
The glass size shown for the drawn
MCR_ 105
Glass 07 Glazed canopies Section 1:10. Junction at top and bottom 12
12 9
13
9 13
Section 1:10. Junction at edge
9
9
13
Plan 1:10. Glazing bar
Example B 9
11
10
Section 1:100. Key section
9
9
13
the sloping rafters are supported at their
ed to glass sheets to give a canopy structure
achieved in bonded or 'structural' glass
base on a beam, and that the top end is fixed
with no visible metal fixings. In generic exam-
canopies already constructed.The laminated
with metal brackets back to the building
ple (C) a series of laminated glass beams are
glass sheets forming the top of the canopy
structure or to the external wall above.The
cantilevered from a supporting floor slab or
are bonded to the top of the glass beam, the
rafters forming the sloping beams are shown
reinforced concrete wall.The beams are can-
beams being made wide enough to provide
fixed rigidly at the bottom of the steel beam,
tilevered from mild steel brackets which are
sufficient bearing for the two abutting sheets
and have a sliding connection at the top in
bolted to the building structure. An L-shaped
of glass. Since three thicknesses of glass are
order to allow for structural movement in
bracket is set either side of each glass beam
usually required for structural safety, the
the rooflight frame. Generally, canopies using
and the beam is clamped in place by bolts
bearing of the glass is a minimum of 10mm.
this captured glazing technique use the tech-
that pass through holes in the glass.This
The joint between the glass sheets is sealed
nique developed for rooflights of similar con-
technique is now well established, and fixing
with a sealing silicone rather than the bond-
struction.
tolerances achieved are very close, allowing
ing silicone used between beams and flat
the bracket to be exposed visually as an ele-
sheet.The use of silicone as a bonding mate-
gant connection within the assembly.The
rial allows the canopy structure of glass
Bonded glass canopies The most recent development in glazed
canopy here is shown projecting 1500mm
beams and sheets to form a rigid structure
canopies has been the use of all-laminated
from the edge of the adjacent glass roof,
that requires no additional support.
glass structures where glass beams are bond-
though much longer spans have been
MCR_ 106
In the generic example (C), the canopy
Train Station, Heilbronn, Germany. Architect: Auer und Weber / Schlaich Bergermann und Partner
Section 1:10. Junction with structure 15
15
15
14
17
Details Section 1:25.Typical assembly
1.
Example C
2. 3. 4. 5. 6. 7. 8. 9. 15
18
17
10. 11.
15
12. 13. 14. 15. 16. 17. 18.
17
Cast mild steel or stainless steel angle bracket Single glazed panel Mild steel or aluminium tube Support bracket Bolt fixing Steel strut secured to primary structure External wall Building structure Extruded aluminium glazing bar Single glazed sheet Aluminium pressure plate and capping Insulated metal panel Silicone sealed joint Silicone bond Single glazed panel Silicone seal Laminated glass beam Steel connector rod secured to primary structure
is sealed against a metal flashing forming the
result of thermal stress imposed by heat
beam to beam. By increasing the number
vertical face of a parapet upstand.The glass
from the sun.
from one interlayer to four interlayers in
is shown continuing over the upstand to
The use of coloured interlayers in lami-
successive beams, the same colour can be
form a glass coping.The vertical edge of the
nated glass has led to the increased use of
used to change the tone within the same
adjacent gutter, formed either in sheet metal
bonded glass canopies as translucent struc-
colour to give a range of graded visual
or in a single layer membrane, is sealed to
tures rather than fully transparent ones.The
effects.The maximum number of interlayers
the glass with a compatible silicone. An addi-
visual benefit of having no visible metal fix-
recommended by glass manufacturers is usu-
tional second silicone seal is provided behind
ings allows the translucent structural mem-
ally four in a single lamination, but five inter-
this outer seal to form a second line of
bers to take full visual priority over the bolt
layers have been used successfully in some
defence against rainwater penetration.The
fixings or glazing bars used in other glazing
applications.The use of coloured interlayers
top of the glass, where it passes over the
techniques.The range of interlayer colours
in laminated glass is set to develop over the
coping, is fritted with an opaque screen print
available has increased dramatically over the
next five years as interlayer manufacturers
to conceal the silicone seal below.The void
past two or three years, allowing gradual
fabricate this material with specific shading
immediately below the glass is ventilated to
changes in tone and colour from beam to
coefficients, or g-values, in order to promote
avoid a heat build-up between the glass and
beam and from sheet to sheet, where
their use as a method of solar control shad-
the top of the coping below, which would
required.The number of interlayers used in
ing.
otherwise cause breakage of the glass as a
laminated beams can also be varied from
MCR_ 107
3 CONCRETE (1) Concealed membrane System assembly Framing profiles Opening lights Parapets, cills, penetrations Corners (2) Exposed membrane System assembly Framing profiles Opening lights Parapets, cills, penetrations Corners (3) Planted System assembly Framing profiles Opening lights Parapets, cills, penetrations Corners
MCR_ 109
Concrete 01 Concealed membrane
1 5
5
4 2 1 2 3
1
Section 1:10. Junction of external wall and roof slab 3
1
Isometric view of assembly 3
3
Section 1:10. 2-way drain outlet
Detail L 2
Detail A
1
Sections 1:10. Expansion joint in concrete slab 4
5 4 7
2
2 1
1
1 3
3
3
Materials
zontal roof to a vertical parapet wall, it can
costs, there have been considerable efforts
Bitumen has traditionally been used as a
pass through a maximum of 45° in a single
made by manufacturers over the past 20
waterproof layer, applied while hot in liquid
fold. For this reason 45°angle fillets are used
years to make the bitumen layers thinner, to
form onto a concrete roof slab. As it cools it
to make a 90° turn from roof to wall.
reduce the material required while enhanc-
hardens, forming an impervious membrane,
Modern bitumen-based membranes that
but will soften again if heated by the effects
are concealed beneath roof finishes are typi-
This has been achieved by replacing the thick
of solar radiation. For this reason, in order to
cally a combination of bitumen-based sheet
2-layer method with a mixture of thin layers,
keep the material cool, bitumen membranes
mixed with synthetic rubber to give flexibility
still applied in hot liquid form on site, but
are concealed by smooth pebbles, paving
combined with a reinforcement to give
reinforced with an elastomeric sheet, usually
slabs, usually with thermal insulation set
dimensional stability and tensile strength.This
bedded between the layers.This is typically
between the bitumen and the
reinforcement often allows the material to
two layers, each 3mm thick with reinforcing
pebbles/paving.Traditional bitumen roofs are
be folded through 90°, making its use con-
layers bedded into the material.This allows
usually laid in two layers, with an overall
siderably easier, where angle fillets are not
the bitumen to accommodate both small
thickness of around 20mm. One of the limit-
required.
amounts of movement at these junctions, as
ing factors with bitumen is folding the mater-
With the development of much thinner
ing its properties of strength and flexibility.
well as the sharp fold in the material, which
ial through a right angle.When the material
membranes in thermoplastics and elas-
creates a weakness in the membrane which
turns through a right angle from the hori-
tomers, together with their competitive
might otherwise be damaged during the life
MCR_ 110
Section 1:10. Expansoin joint in concrete slab
Detail B
Section 1:10. Junction of external wall and roof with slot drain
4 4
8
3 2
1 3
3
1 3
Section 1:10. Expansoin joint in concrete slab
3
Detail C
4
Details
1
1 3
3
International Port Terminal,Yokohama, Japan. Architect: Foreign Office Architects.
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.
Section 1:10. Junction of external wall Waterproof membrane and roof with overflow Thermal insulation Concrete deck 1 Paving slabs Smooth pebbles 2 Parapet coping Rainwater outlet Slot drain Opening for overflow Reinforcement at fold if required Proprietary movement joint 9 Balustrade Pipe or duct Filter sheet
4
1
2
1
3
of the building. An outer protective layer is
main areas of roof are waterproofed in
ester filter sheet is set on top, with paving or
added for vulnerable locations such as at gut-
order to allow external walls to be complet-
smooth pebble ballast on top to hold the
ters and at upstands.
ed.When an area is completed, the roof
insulation in place as well to walk on. Pebbles
Concealed membrane roofs are increas-
deck is waterproofed and finished, with areas
are 20mm - 40mm diameter, while paving
ingly being laid flat with no fall, unlike
of flat roof being bonded continuously to
slabs are around 600 x 600mm in size, 30
exposed membranes, where a slight fall is
the already completed upstands.This avoids
mm - 40mm deep. In the sealed joint config-
always required.This is partly because bitu-
the need to protect the membrane, which
uration, the bitumen membrane with its pro-
men bonds more reliably to a concrete slab
has attendant risks of being damaged before
tection layer has a drainage layer on top,
than to a thin screed, and partly because the
the building is finished.
onto which is laid a minimum 65mm
slopes required to create falls in large areas
Concealed membrane roofs are typically
sand/cement screed, usually reinforced or
of flat roofs create difficulties in level changes
in 'inverted' roof configuration with either
made sufficiently thick to avoid cracking both
across the roof which can be difficult to
open joints or sealed joints in the top layer
in the screed and the sealed paving above.
drain.The more traditional methods of
that covers the thermal insulation, usually
Paving slabs or blocks are bonded to the
screeds laid to falls and thick layers of bitu-
paving. In the open joint version, the mem-
screed with mortar and grouted.
men is used where the roof finish is sealed,
brane, bonded to the concrete slab, is cov-
such as paving with sealed joints.
ered by a protection layer, with closed cell,
Typically upstands are formed before the
rigid thermal insulation set on top. A poly-
Structural joints The main advantage of concealed mem-
MCR_ 111
Concrete 01 Concealed membrane 4
4 2 1 7 2
2
3
1
1
3
Section 1:10. Open jointed paving
3
4
1
Section 1:10. Rainwater outlet
2
Detail H
Section 1:10. Low parapet
Detail D
1 3
10
2
6
Section 1:10. Sealed paving 1
Section 1:10. Proprietary expansion joint 4
5
4
4
11
1
2 1
1 3
3
3
branes is their ability to span movement
itself, held in place by an additional protec-
water at this lower level can discharge into a
joints and expansion joints in reinforced con-
tion sheet on top.The gap between the
rainwater outlet.
crete slabs with simple, reliable details that
membrane, dipped into the joint, and the
require no upstands to form the junction.
reinforcement cover is filled with a foam
and walls are treated in a similar way, with
Expansion joints between concrete slabs of
backing rod or tube, as used in the glass
the membrane dipping down into the gap
widths between around 10mm to 50mm are
joints of bolt fixed glazing.The material used
between wall and roof and the membrane
formed by stopping the material each side of
for the reinforcement is either the same
continuing up the wall. Reinforcement is sim-
the joint and setting a rubber-based strip that
bitumen based material, or increasingly, a
ilarly applied, with a rubber-based strip fold-
dips into the gap between the slabs as (A),
rubber-based strip.
ed through the 90° corner rather than the
linking the membranes into a continuous seal.
The top of the joint is finished as level as
Junctions between concrete roof slabs
maximum 45° folds that are usually allowed
As the gap between the slabs varies with
possible with the adjacent areas of roof to
structural movements, the rubber-based strip
allow water to drain freely from the roof.
is allowed to move without being stretched
The reinforcing membrane is sometimes
are used to form part of the visible finishes,
significantly.The joint is protected and rein-
folded down into the gap, separated from
typically with sealed roof finishes. In this case
forced with an additional layer, either flat and
the membrane below with a foam backing
the seal is formed by bonding a strip of
bonded on one side only, or formed as a
rod. It can be difficult to drain water from
membrane to the metal assembly.The metal
folded, S-shaped cover that folds back over
this groove at the edge of the slab unless
expansion joint assembly is fixed on top of
MCR_ 112
in traditional bitumen-based membranes. Proprietary metal-based expansion joints
Section 1:10. Rainwater outlet
Detail J
Section 1:10. Junction of external wall and roof slab
7
4
5
4
2
2
1
1
5
2
1
1
3 3
3
Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
Section 1:10. Plinth
1
Waterproof membrane Thermal insulation Concrete deck Paving slabs Smooth pebbles Parapet coping Rainwater outlet Slot drain Opening for overflow Reinforcement at fold if required
11. 12. 13. 14.
Proprietary movement joint Balustrade Pipe or duct Filter sheet Section 1:10. Door sill
Detail E
4 5
4
1
2
2
2 1
1 3
3
the membrane, which still dips down into
where there is a risk of damage during con-
the joint. A foam backing rod is set on top of
struction.
the dipped membrane and is covered with a bed of compatible sealant to ensure that any water that penetrates the movement joint is
In (D) a low parapet wall is terminated by a concrete or stone coping.The waterproof membrane extends up the height of
Parapet upstands In forming parapet upstands, an essential
the upstand, which runs horizontally to form a full damp proof course underneath the
drained to the sides of the movement joint.
requirement is to keep the waterproof
coping.This ensures that the membrane pro-
The waterproof membrane is then formed
membrane as well protected from the
vides a continuous waterproof layer at the
up out the base of the movement joint
effects of the sun as elsewhere on the roof.
junction with the external wall. An additional
assembly to provide a complete seal across
For this reason, thermal insulation is applied
metal flashing to cover the top of the metal
the joint.
to the inside face of the parapet even if this
faced insulation to protect the junction
has no direct benefit to the passage of heat
between the top of the metal facing to the
precast concrete slabs, where only negligible
through the building.The membrane is
insulation, and the insulation itself. In (D) an
structural movement is expected, are also
turned through a full 90° as shown in the
open jointed arrangement of paving slabs is
formed with rubber-based strips.The mem-
drawings, but an angle fillet is required by
shown, with rainwater draining at the level of
brane forms a continuous lapped joint
some manufacturers to limit the angle of any
the membrane.To assist with the drainage of
across the rubber-based strip, as (B) and (C),
fold to 45°. A reinforcing strip is usually
the rainwater from the parapet coping, a
with a foam backing rod being provided
added where a 90° fold is made.
strip of pebbles is shown.This avoids staining
Joints between concrete panels, such as
MCR_ 113
Concrete 01 Concealed membrane
12
4
5
4
1
5
2
2 1
2 1 3
3
Section 1:10. Junction of external wall and roof slab
Section 1:10. Base of balustrade
Section 1:10. Base of balustrade
Section 1:10. Pipe penetrations
Detail F
13
13 4
5
4
5
2
2
1
2
2
1 3
3
of the roof level paving where it meets the
waterproof membrane.The balustrade base
columns for the support of roof-mounted
parapet upstand by allowing rainwater run-
plate is bolted through the membrane to
mechanical equipment are waterproofed in
ning off the inside face of the parapet coping
the concrete slab below. If the membrane
a similar way to a parapet upstand.The
to drain through the pebbles to the mem-
has an additional protection layer, then this is
membrane is folded up through 90° from
brane beneath. In (E) the paving is shown
usually omitted around the base plate to
the roof level and is formed to cover the
continuing up the parapet upstand. Since the
give a more reliable seal. An additional mem-
complete plinth. Detail (G) shows a rail sup-
sill to the external door shown in the detail
brane is then laid on top of the base plate
porting an I-section that would support an
covers the opening, and is supported from
with the protection layer. Alternatively, a rub-
air handling unit or a rail for a cleaning cradle
the base of the opening, the waterproofing is
ber-based seal is bonded to the top of the
trolley.The thermal insulation extends across
shown stopping at the edge of the opening.
base plate to provide a secondary seal to
the complete plinth to prevent a thermal
As can be seen from these two details, the
the penetrations in the membrane formed
bridge through the roof construction.
termination of the membrane varies with
by the bolts securing the base plate.The
each situation.
polyester filter sheet, set loose laid on top of the insulation in the detail, is wrapped
Balustrades and plinths The balustrade post shown in (F) is fixed to a base plate which is set onto the finished
MCR_ 114
Rainwater outlets The rainwater outlets shown in (H) and
around the balustrade post below the level
(J) are set at the level of the waterproof
of the paving.
membrane, with that shown in (J) is shown
Plinths which are formed as short
drained at both the level of the sealed
Section 1:10. Pipe penetrations
Section 1:10. Pipe penetrations
Detail N
13 13
5
5
4
2
2
4
2
2 1
1 3
3
3
3
Details Section 1:10. Pipe penetrations
1. 2. 3. 4. 5. 6. 7.
Detail M
13
Waterproof membrane Thermal insulation Concrete deck Paving slabs Smooth pebbles Parapet coping Rainwater outlet
8. 9. 10. 11. 12. 13. 14.
Slot drain Opening for overflow Reinforcement at fold if required Proprietary movement joint Balustrade Pipe or duct Filter sheet
International Port Terminal,Yokohama, Japan. Architect: Foreign Office Architects.
5
4
2
2
1 3
3
Penetrations for pipes and ducts
paving and the level of the waterproofing
requires regular visual inspections by lifting
layer. In (H) the base of the rainwater outlet
up the paving slab immediately above to
is fixed to the concrete slab.The waterproof
remove any debris that might collect in the
ing an upstand around the opening, or by
membrane is dressed down into the top of
gap between the rainwater outlet and the
forming a metal collar around the pipe or
the rainwater outlet and the upper part of
thermal insulation adjacent to it.
duct, similar to the balustrade detail men-
the rainwater outlet is bolted down onto
The rainwater outlet in (L) is used
Penetrations are sealed by either form-
tioned earlier. Where a concrete upstand is
the part already fixed and sealed.The geot-
increasingly to drain roof terraces into exter-
formed, a metal flashing is welded or
extile sheet is wrapped around the outlet to
nal rainwater pipes fixed to the facade, or to
mechanically fixed and sealed to the pene-
avoid dirt and debris being washed into the
a void immediately behind the facade, with-
trating pipe or duct as shown in (M). In (N)
rainwater drainage system. In (J) the rainwa-
out the need for a visible opening in the
a metal sleeve is bolted through the mem-
ter outlet is fixed in the same way, but the
parapet wall that is visually unappealing.The
brane and a reinforcing rubber-based disc is
cover is much lower, since rainwater is
2-way outlet is fixed in two parts in the
bonded to the top of the base plate.The
drained only at the edges of the cover, and
same way as the outlets in (H) and (J). A
pipe is set into this sleeve and is sealed with
not through its full height as is the case in
25mm gap is shown between the parapet
a tension clip at the top of the sleeve. In (M)
(H). In (J) the filter sheet is tucked down into
wall and the edge of the paving slab to allow
the pipe flashing detail allows the pipe to be
the edges of the rainwater outlet. Because of
rainwater to drain into the outlet.
both thermally insulated and independent of
its concealed position, the rainwater outlet
the enclosing sealed sleeve.
MCR_ 115
Concrete 02 Exposed membrane
11
1 2
3
Natural Unit / Studio House. Architect: Masaki Endoh and Masahiro Ikeda.
Section 1:10. Bonded method. Junction of external wall and roof slab Section 1:10. Bonded method. Pipe penetration
Section 1:10. Bonded method. Rainwater outlet
Section 1:10. Bonded method. Upstand for balustrade 11
10
7 1 1 2
1
2
2
3
3
3
Exposed membranes have been used for flat
been replaced. In practice these roofs were
between the roof deck and the adjoining
roofs which are not visible from below, but
patched up where leaks occurred since it
elements would sometimes result in the
this has changed in recent years as mem-
was considered to be a major undertaking
roofing sheet splitting or tearing, allowing
branes are produced in increasingly smooth
to install a completely new roof covering.
rainwater to penetrate the roof construc-
and regular finishes. Because of their light-
Damage to the bitumen-based roof materi-
tion.The weakness of these materials was
weight nature, they are often used in con-
als was typically a result of a lack of flexibility
partially overcome by introducing added sac-
junction with lightweight roofs such as pro-
of the membrane that could not easily
rificial layers. Although this had the advantage
filed metal deck and timber. This section con-
accommodate thermal and structural move-
of reducing risk of the membrane being
siders their use in concrete construction,
ments as well as deflections in the building
punctured by foot traffic during mainte-
though the same principles of waterproofing
structure. Although concrete roofs slabs are
nance, this method did not add any substan-
can be applied to these other materials.
less susceptible to thermal movement than
tial strength to the membrane and damage
some other materials, interfaces between
would occur as before.
It was still commonly the case 30 years ago for exposed membranes on concrete
wall and roof, or roof and rooflights, for
roofs to be made from bitumen or bitumen-
example, would often result in damage to
membranes provided economic waterproof-
based sheet materials.This material was
the roof membrane where the roofing sheet
ing materials that were more flexible than
expected to last around 10-15 years, after
continued across the joint at the junction of
their bitumen-based predecessors. First
which time the roof covering should have
the two materials.The structural movement
introduced in the 1960's and 1970's, they
MCR_ 116
The introduction of polymer-based
Section 1:10. Bonded method. Junction with rooflight
Details Waterproof membrane 2. Thermal insulation 3. Concrete deck 4. Paving slabs 5. Smooth pebbles 6. Parapet coping 7. Rainwater outlet 8. Opening for overflow 9. Balustrade 10. Pipe or duct 11. External wall 12. Rooflight
Section 1:10. Bonded method. Junction of external wall and roof slab
1.
12
11
1
1
2
2
3
3
Section 1:10. Bonded method. Low parapet
Section 1:10. Bonded method. Roof fold
6
1
1 2
2 1
11 2
3
became much more widely used in the 1980's and 1990's.The increased flexibility of
3
Polymer-based membranes The main advantage of the polymer-
plastics are preferred in Europe. EPDM (ethylene propylene diene monomer) is a flexi-
the new sheet materials allowed for greater
based sheet materials is their ability to be
ble and elastic material that has the appear-
amounts of movement between adjoining
cut and formed to complex shapes, allowing
ance of a synthetic rubber. EPDM is manu-
components and assemblies, allowing the
them to take up shapes precisely, sometimes
factured in the limited colours of black, grey
detailing of junctions to be relatively straight-
pre-formed in the factory before being
and white.
forward in forming reliable weathertight roof
delivered to site. Single layer membranes are
membrane. As a result of these develop-
very practical on roofs with a large number
be mechanically fixed, bonded or secured
ments, polymer modifications were also
of penetrations, typically in commercial build-
with ballast to the concrete deck beneath.
made in the older-generation bitumen-based
ings where mechanical ventilation equipment
Developments in these materials has led to
materials to make them more flexible, in
is regularly being modified or replaced dur-
them being used on timber decks and pro-
order to compete with the polymer-based
ing the lifetime of a building.
filed metal decks in addition to the concrete
sheet materials. As a result there is now a
Single layer membranes are made from
Both elastomers and thermoplastics can
decks discussed here. Both thermoplastic
wide range of exposed membrane materials
either elastomeric materials, typically EPDM,
and EPDM membranes can be welded
available to suit different budgets and individ-
or from thermoplastic materials, typically
together to form a continuous waterproof
ual roof designs.
plasticised PVC (PVC-P). Elastomeric materi-
sheet.While both material types were glued,
als are very popular in the US while thermo-
there is an increasing use of hot air welding
MCR_ 117
Concrete 02 Exposed membrane
1
11
11
1
2
2
3
3
Sections 1:10. Bonded method. Junctions of external wall and roof slab Section 1:10. Bonded method. Roof overflow
Section 1:10. Bonded method. Gutter
Details 1.
1
Waterproof membrane Thermal insulation Concrete deck Paving slabs Smooth pebbles Parapet coping
2. 3. 4. 5. 6.
11
1
7. 8.
Rainwater outlet Opening for overflow 9. Balustrade 10. Pipe or duct 11. External wall 12. Rooflight
2
Section 1:10. Bonded method. Roof fold
Section 1:10. Bonded method. Pipe penetration
8 10 1
1
2
2
1
1 2
3
1
2
2
11 3
3
3
methods, which avoid the need for flame
1960's and were used in the US from the
low levels of shrinkage, and is dimensionally
techniques or adhesive bonding methods
1970's onwards. PVC sheet material is usual-
stable and does not creep visibly with age.
that can be both slow and can damage adja-
ly reinforced with glass fibre to give it
The material experiences only very small
cent work during their application. In hot air
increased rigidity that is easier to bond to
amounts of movement under full wind load.
welding, a jet of heated air is used to soften
the substrate.
the materials and weld together, applied from
The PVC used in membranes is plasti-
Membranes are reinforced with glass fibre sheet or polyester fabric.These layers
a range of tools that are either hand held or
cised (PVC-P), unlike the unplasticised PVC
are bonded into the material.The glass fibre
fully automated, depending on the applica-
(PVC-U, or uPVC) used to make window
provides dimensional stability, making it more
tion.
frames and rainwater drainage components.
stable for bonding to the substrate.The
PVC-P is rigid at normal external tempera-
woven polyester fabric, used in tent mem-
tures, but softens when heated, making it
brane structures, has high tensile strength to
PVC membranes PVC (polyvinyl chloride) roof mem-
flexible and allowing strips or sheets to be
resist wind loads the mechanically fixed
branes have been in use since the 1960's as a
welded together to form a continuous
method is used. A typical build-up for a sin-
very lightweight and relatively economic
membrane without the need for standing
gle layer membrane is a concrete deck with
roofing material, and has become widely used
seams or visible joints. Plasticisers and filler
a vapour barrier set on top, with thermal
in recent years. Membranes in this material
material in PVC-P is added to give the mate-
insulation above that, sealed on top with a
were first developed in Europe in the late
rial greater flexibility.The material has very
single layer membrane. PVC-P membranes
MCR_ 118
Section 1:10. Ballusted method. Rainwater outlet
Section 1:10. Ballusted method. Eaves
Section 1:10. Ballusted method. Junction with rooflight
7
5
4
1
1 2
5
2 4
3
2 3 11 3
Section 1:10. Ballusted method. Low parapet
Section 1:10. Ballusted method. Upstand for balustrade
5
5 4
11
4
4
1
1
1 2
2
2
3 3
3
Sections 1:10. Ballusted method. Junctions of external wall and roof slab Section 1:10. Ballusted method. Pipe penetration 10 5
11
5
5
1 2
4
4 1
2
1
2
2 11
3
3
are typically 1.5mm - 3.0mm thick, while EPDM membranes are typically 1.0mm 1.5mm thick.
FPO (TPO) membranes A recent development in thermoplastic
3
3
Mechanically fixed method This fixing method is suited to applica-
those used in glazed curtain walling systems to hold the glass in place. Bars form strips of
tions with high wind uplift forces, as bonded
pressure plate to hold the roof build-up in
systems tend to be limited by the bonding
place.The pressure plates are fixed by bolts
strength of the vapour barrier to which the
at centres along their length to the substrate
membrane is itself bonded through the ther-
below. Membranes can also be secured by
membrane types are polypropylene- and
mal insulation layer, which is typically made
polyethylene-based materials.They have
from expanded polystyrene board.The
point fixings rather than by pressure plates.
greater flexibility than PVC-P membranes,
vapour barrier is loose laid on the concrete
50-75mm diameter rigid plastic discs are
but still require reinforcement in glass fibre
deck and thermal insulation is then mechani-
used to hold the build-up in place.These are
sheet for increased dimensional stability and
cally fixed through this barrier to the deck
set at centres to suit the design wind loads.
polyester fabric to give greater tensile
beneath.The spacing of the fasteners varies
The closed cell rigid insulation is typically
strength. Fire retardant is added to provide
with the design wind loads. A separating
made in panel sizes of 1200mm x 2400mm
fire resistance, unless PVC-P which is self-
layer of glass fibre sheet is usually laid onto
in thicknesses from 25mm to 100mm.
extinguishing when flame is applied.
the insulation with an outer single layer membrane.The membrane is mechanically fixed with pressure plate bars, similar to
Bonded fixing method The build-up of materials is the same as
MCR_ 119
Concrete 02 Exposed membrane 6
1 11
1
2
12
2
3
3
Section 1:10. Mechanical fastening method. Low parapet
Section 1:10. Mechanical fastening method. Junction with rooflight
1
Natural Unit / Studio House. Architect: Masaki Endoh and Masahiro Ikeda.
Details
1
2
1. 2. 3. 4. 5. 6.
2
3 3
Sections 1:10. Mechanical fastening method. Roof fold
Waterproof membrane Thermal insulation Concrete deck Paving slabs Smooth pebbles Parapet coping
7. 8. 9. 10. 11. 12.
Rainwater outlet Opening for overflow Balustrade Pipe or duct External wall Rooflight
Sections 1:10. Mechanical fastening method. Junctions of external wall and roof slab
Section 1:10. Mechanical fastening method. Pipe penetration
10
11
11 1
1 2
1
2
2
3
3
3
that for the mechanically fixed system.The
beneath.The membrane is then bonded to
membrane can either be bonded directly to
the insulation with a continuous layer of
the concrete deck to form a concealed
bonding adhesive on its underside. Some
cally fixed to parapet upstands.The fixing
membrane, or be in the exposed configura-
systems still bond the membrane at points
method that is used on the main area of
tion discussed here.When bonded directly to
only rather than across the entire surface of
roof is usually continued on these vertical
the concrete deck, a felt backing layer is usu-
the membrane, but this is dependent upon
areas.With mechanical fixing the pressure
ally used to overcome any roughness in the
the wind load and the proprietary system
plate can be fixed either to the upstand or
substrate that would puncture the material.
used.
to the flat roof area.The pressure plate
In the exposed membrane configuration the
Bonded membranes have a visually
Parapets and upstands Membranes can be bonded or mechani-
forms a junction between the membrane
vapour barrier is usually bitumen-based and
smooth appearance, making it suitable
sheet forming the upstand and the mem-
is bonded to the deck. Joints between the
where the roof surface is seen from points
brane sheet of the roof. Intermediate pres-
vapour barrier sheets are lapped to avoid any
around the building. It can be more difficult
sure plates are applied horizontally on the
risk of vapour passing through the roof struc-
to achieve the bonding required for high
upstand when its height exceeds around
ture from inside the building.The thermal
wind uplift conditions, but this is a matter of
500mm, depending on the specific material
insulation is then bonded to the vapour bar-
individual design.This fixing method still
used.
rier. Insulation can also be mechanically fixed
requires mechanical fixing at the edges, and
with pressure plates to the concrete deck
around openings such as rooflights.
MCR_ 120
8
11
1
1
11
2
2
3
3
Section 1:10. Mechanical fastening method. Roof overflow
Section 1:10. Mechanical fastening method. Junctions of external wall and roof slab Section 1:10. Mechanical fastening method. Pipe penetration
10
Section 1:10. Mechanical fastening method. Rainwater outlet 7
1
1
2
3
2
3
3
3
Section 1:5. Mechanically fastened pressure plate fixing
Section 1:5. Mechanically fastened point fixing
Ballasted roofs Concealed membranes which are ballasted use a top layer to weigh down the membrane and insulation rather than use
1
1 2
2
mechanical fixing or bonding methods. A typical build-up consists of a single layer membrane welded together to form a continuous sealed sheet, which is loose laid onto
3
3
a concrete deck. A backing felt is used where the concrete is considered to be too roughly finished for the membrane to be laid directly on top.Thermal insulation is loose laid onto the membrane with a filter layer set onto the insulation. Smooth pebbles are spread on top, to a depth dependent upon both the weight required to avoid wind uplift as well as to satisfy visual requirements.
MCR_ 121
Concrete 03 Planted Details 1. 2. 3. 4. 5.
6. 7. Light vegetation 8. Heavy vegetation Soil / growing medium 9. 10. Filter sheet 11. Drainage layer
Waterproofing layer Thermal insulation Vapour barrier Concrete deck Smooth gravel Coping
12. 13. 14. 15.
Detail A
Pipe / duct Supply pipe Rainwater outlet Wall cladding
1
Detail E
10 3
1 10
5 3 4
4 7
7 15
8
9
9
15
Section 1:10. Light planting. Eaves and parapet junctions. Section 1:10. Light planting. Upstand.
Section 1:10. Light planting. Rainwater outlet. 1
1 10
14
10
3
3 5
5
1
4
4
10
7 3
7
8
4
8
7 9
8
9
9
Concrete decks used for planted areas can
ers that require little maintenance and do
pipes set into the soil that provide a trickle
be waterproofed with either a concealed
not usually have an irrigation system to sup-
water feed to the soil at specific times which
membrane or an exposed membrane as dis-
ply water at controlled times, relying on rain-
may vary during the course of the year.
cussed in the previous sections. Planted roofs
water and modest amounts of watering dur-
Heavy planted roofs require regular mainte-
are of two types: light planted and heavy
ing maintenance at specific times of the year.
nance, provided by paved paths or by areas
planted. Unlike other concrete roof types,
These lightweight planted roofs suit a light-
of grass.
planted roofs are not always insulated as they
weight deck, such as a thin concrete shell,
often form the roof of underground struc-
although profiled metal decks are commonly
roofs have drainage layers beneath the
tures such as car parks, providing a planted
used as substrates. Maintenance access is
growing medium that hold water and release
roof at ground level.
provided by the pebble strips at the roof
it back to the plants when required.This
edges or by individual paving slabs that
allows the soil depth to be much less than
avoids the need to walk across the planting.
that which would be required for older land-
Heavy planted roofs permit a wide vari-
scaping methods, where the soil was expect-
Light planted roofs have resilient plants that require little or no irrigation, and that will grow in a thin layer of soil or organic
Both light planted and heavy planted
growing medium.They are not usually used
ety of plants, shrubs and trees to grow on a
ed to hold all the water.The reduced depth
on a roof accessible to building users, but are
concrete roof deck. Due to the size and
of soil allows planting to be considered for
seen from vantage points around the build-
intensity of the planting they require an
concrete roof structures that would require
ing. Light planted roofs have plants and flow-
automated irrigation system, usually from
no significant strengthening to receive the
MCR_ 122
Section 1:10. Light planting. Cill junction.
Prefectural University,Tokyo, Japan. Architect: Riken Yamamoto and Field Shop.
Section 1:10. Light planting. Rooflight upstand. Detail D
1
1
3
3 4
4 7
7 6
6
9
9
Section 1:10. Light planting. Pipe penetration.
Section 1:10. Light planting. 2-way outlet. 12
1
1
4
1
3
3 5
6
3 5
8
9
4
5
7
7
8
9
7 8
9
added weight of soil. In terms of drainage it
this is reduced due to the varying amounts
and pH values required by the plants chosen.
is estimated by manufacturers of proprietary
of water held within the soil. A root barrier
Both the soil mix and the soil depth deter-
systems that 50% to 90% of rainfall is
is set beneath the insulation to protect the
mine the amount of plant growth that can be
retained in planted roofs, but this varies con-
waterproof membrane, which forms the
expected on a planted roof.
siderably with local climate conditions and
bottom layer, which is bonded to the con-
To prevent the passage of organic matter
rainwater drainage provision.
crete roof deck.The root barrier is some-
and fine particles into the water drainage sys-
times bonded to the waterproofing layer,
tem, a filter sheet is set underneath the plant-
usually when the complete build-up is a sin-
ing.This sheet is lapped up the sides of the
gle proprietary system.
planting, where it meets an upstand, to the
Planted roof components Both light planted and heavy planted roofs have a similar build-up, comprising typi-
The essential requirements for stabilising
level of the planting. The drainage layer beneath the filter
cally a top layer of planting, with a growing
and maintaining plant growth in planted
medium or soil beneath. A filter layer is set
roofs are the provision of nutrients in the
sheet retains water that drains through the
underneath, and below this, a drainage layer
growing medium, water retention, soil aera-
planting.Water is retained in profiled troughs
and moisture mat. Beneath this lowest layer
tion and drainage. Soils used are aimed to be
in a typically polystyrene egg-crate shaped
is set thermal insulation if required. Although
relatively low in weight but are balanced to
tray that releases water back to the planting.
planted roofs provide a limited amount of
suit the nutrients, soil porosity, vapour per-
This method also performs satisfactorily on
thermal insulation from the soil, in practice
meability (from the drainage layer below)
sloping concrete roofs. Excess water is
MCR_ 123
Concrete 03 Planted
2 10 2
3 10
3
5 6
5
4
4 7
6
8
7 8
9 9
Section 1:10. Heavy planting. Cill junction.
Detail B
Section 1:10. Heavy planting. 2-way outlet.
Section 1:10. Heavy planting. Pipe penetration.
Section 1:10. Heavy planting. Cill junction.Planter edge.
12 2
2
2 10
10 3
3
3 4
4 6
6 7
7 8
8
9
9
9
drained away through gaps between the
the waterproof membrane is set on top of
25° to 30°. Heavy planted roofs have a
drainage trays.The egg-crate form allows
the thermal insulation, positioning the insula-
deeper drainage layer to provide greater
aeration, permitting the soil to absorb the
tion within the building envelope. A vapour
water storage.The soil depth, in excess of
water stored here. In drier months, water
barrier is set between the thermal insulation
150mm, requires an automatic irrigation sys-
diffuses up through the soil to the plant
and the concrete deck. In this configuration a
tem to provide a reliable water supply cov-
roots. A moisture mat is often set under this
moisture mat is set between the waterproof
erage of the complete roof.
layer to catch water that runs off the
membrane and the drainage layer above.
drainage layer.The mat is made from a durable fibre that retains moisture and nutrients as well as serving as protection to the
In inverted roof configurations, the weight of soil and vegetation is made suffi-
Soil depth
cient to avoid wind uplift and the possibility
The soil depth in light planted roofs
of the insulation floating on the water during
root barrier beneath. It is not used in invert-
ranges from 50mm to around 150mm,
rainfall. Although the ponding is often consid-
ed roof configurations. In inverted roofs, a
weighing a minimum of around 70kg/m of
ered by proprietary waterproofing manufac-
root barrier is set immediately below the
roof area.Water is stored in the growing
turers not to affect the waterproofing layer, it
insulation to protect the waterproof mem-
medium and drainage layer, making it efficient
can cause lightweight planted roofs to 'float'
brane forming the lowest layer.This layer
in mild, temperate climates. Light planted
during rainstorms if this layer is not properly
prevents planting roots from damaging the
roofs can be grown on both nominally flat
secured.
waterproofing. In warm roof construction,
roofs and on sloping roofs with a pitch up to
MCR_ 124
2
Section 1:10. Heavy planting. Rooflight upstand.
Section 1:10. Heavy planting. Low parapet.
2 10 2
3 10
4
3
5 6
4
5
7
6
8
15
7 8 9
9
Section 1:10. Heavy planting. Rainwater outlet.
Detail F
Section 1:10. Heavy planting. Upstand.
Detail C
2 10
14
Details 1.
2
2.
10
3
4
4
3.
2
3
10
4. 5. 6.
6
7.
3 4
6 7
7 7 8
8 9
9
9
8. 9. 10. 11. 12. 13. 14. 15.
Overflows Irrigated heavy planted roofs are usually
Roof junctions At upstands and eaves the same princi-
Light vegetation Heavy vegetation Soil / growing medium Filter sheet Drainage layer Waterproofing layer Thermal insulation Vapour barrier Concrete deck Smooth gravel Coping Pipe / duct Supply pipe Rainwater outlet Wall cladding
thermal insulation, and typically either paving turned on edge (the same paving used for
provided with overflow outlets so that, in the
ples apply to planted roofs as discussed in
adjacent access paving) or a metal sheet to
event of the rainwater outlets being blocked,
the previous sections on concealed mem-
match that of the parapet coping where a
a high rainfall or failure of the irrigation con-
branes and exposed membranes.The water-
metal coping is used.
trol equipment does not cause the roof to
proofing extends a minimum of 150mm
flood with water. Overflows are set typically
above the level of the planting, providing a
trims, usually from a minimum 3mm thick
at a height between 50mm and 150mm
continuity from the roof membrane to the
folded aluminium sheet or stainless steel
above the planting level to avoid flood dam-
flashing at the top of the upstand or to the
angle.The filter sheet is folded up the inside
age to both the planting and to the interior
adjacent wall construction. Upstands for
face of the angle to avoid organic matter and
of the building.When the roof is laid to falls,
parapets and door sills, high walls and
fine particles from being washed down into
some overflows are set at the level of the
rooflights shown in details (A), (B), (C) and
the drainage layer.The waterproof mem-
highest finished roof level in order to avoid
(D) respectively are formed by extending
brane is bonded to the base of the metal
planting being damaged should flooding
the waterproof filter sheet and root barrier
angle as shown in (E), where the edge is ter-
result in landscaping being temporarily sub-
up to a minimum of 150mm above the level
minated by a paving slab. Smooth pebbles
merged in water.
of the soil or growing medium.The visible
can be used, provided there is no risk of
membranes and sheets are concealed with
them being pushed over the edge, particular-
Eaves can be formed by metal edge
MCR_ 125
Concrete 03 Planted
16
17
18
16
17
Plan, section, elevation 1:10. Small balcony planter.
1
18
18
16
2 5 9
17 17
17
6 7
Example G
ly during maintenance work. Many planted roofs have low parapet or eaves edges so
Rainwater outlets The filter layer is dressed up around the
its top edges, then the water is drained by an internal waterproof tray into the transom
that the roof can be experienced visually
vertical edges of the rainwater outlets as (F).
below, where it drains to the outside.The
from the outside of the building. A fall arrest
An access cover is provided for maintenance
curtain wall system, which is drained and
system is provided, such as harnesses worn
purposes.Water drains at the level of the
ventilated internally, allows any water that
by maintenance personnel, which is attached
waterproof membrane, which is dressed into
penetrated these planter seals to drain
by a safety line to an anchor point or a latch
the base of the outlet.
through its pressure equalisation chambers.
way cable. Balustrades are provided for building users in conditions with low parapets. Vegetation barriers are provided at roof
A glazed balustrade is shown behind the
Balcony planters Planting troughs with automatic irrigation
planters, indicating that the planter would be maintained from the facade cleaning system,
perimeters, upstands, duct penetrations and
and a drainage system can be incorporated
typically cleaning cradle. In (H) and (J) larger
rainwater outlet points to avoid damage to
at roof level into curtain wall facades, as
versions of this planter are shown that are
the adjacent construction that would be
shown in (G), (H) and (J). In (G) a small
suitable for much larger plants.The planters
caused by plants. Pebbled strips with a mini-
planter is integrated into a balcony.The
are drained internally in the same way. In all
mum width of 300mm are used, with river
planter is sealed, but should any water leak
planters water is supplied at one end, typi-
washed pebbles of 16mm to 32mm diame-
either from the planter (as a result of dam-
cally by a water supply pipe of small diame-
ter.
age) or if water penetrates the seals around
ter set into the roof finishes.The drainage
MCR_ 126
Example H
Sections 1:10. Large balcony planters.
Details 1. 2. 3. 4. 5. 6. 7. 8. 9.
Light vegetation Heavy vegetation Soil / growing medium Filter sheet Drainage layer Waterproofing layer Thermal insulation Vapour barrier Concrete deck
10. 11. 12. 13. 14. 15. 16. 17. 18.
Smooth gravel Coping Pipe / duct Supply pipe Rainwater outlet Wall cladding GRP planter Glazed external wall Glass balustrade
Example J
1
2 16
18
18
5
6
1
7
9
2 16 17 17
5
7 6
9
pipe is typically of 50mm diameter for such installations, and is set either within the facade panels or directly in front of the facade. Planter boxes are made from glass reinforced polyester (GRP) which is moulded to form a single, sealed shell.This material is very resilient and can be moulded by hand to suit individual project requirements. Planter boxes made from thermoplastics are much more expensive to manufacture, requiring large numbers to be fabricated at the same size to make them economic.The boxes are set into a metal frame provided within the curtain walling system and are sealed with silicone around their edges. In this example, a metal strip is set on top of the planter to conceal the GRP from view.
Prefectural University,Tokyo, Japan. Architect: Riken Yamamoto and Field Shop.
MCR_ 127
4 TIMBER (1) Flat roof 1: Mastic asphalt coverings Warm and cold roofs The material Warm roof build-up Solar protection Upstands Eaves and verges Penetrations Gutters and rainwater outlets (2) Flat roof 2: Bitumen-based sheet membranes The material Roof build-up Solar protection Fixing methods Parapet upstands Junction with tiled roof Eaves and verges (3) Pitched roof : Tiles Plain tiles Interlocking tiles Ventilation Eaves Ridges Verges Hips and valleys Abutments (4) Pitched roof : Slates Roof folds Vents Monopitch ridges Dormer windows Abutments (5) Pitched roof : Metal Standing seam cold roofs Eaves and valley gutters Ridges and abutments Penetrations Metal tiled roofs
MCR_ 129
Timber 01 Flat roof : Mastic asphalt coverings 9
9
12
12 1 3
3 4
10
4
4
6
6
2
2
7
7
8
8
Section 1:10. Expansoin joint 8
Section 1:10. Drain outlet at parapet wall
Section 1:10. Eaves Saltwater Pavilion, Neeltje Jans, Holland. Architect: Oosterhuis Associates.
12
11
1 1
13
5
3 12
4 6
6 2
2
7
Warm and cold roofs
that avoids the possibility of rot forming in
cold roof configuration, the asphalt is set
Flat timber roofs are described as being in
the timber. A vapour barrier is set beneath
directly onto the timber deck, with a sepa-
either 'warm' roof or 'cold' roof configura-
the insulation, on the warm (in winter) side
rating layer beneath the asphalt.
tion. In the warm roof as (A), thermal insula-
of the insulation, with a dry wall or internal
tion is set on top of the timber deck, which
lining board set below this. In both warm
is protected by a waterproof layer set onto
and cold roofs, the vapour barrier avoids the
its upper face. A vapour barrier is set
passage of damp air up into the thermal
which is blended with limestone powder and
between the thermal insulation and the tim-
insulation where interstitial condensation can
fine limestone aggregate. 'Lake' asphalt is
ber deck.The roof build-up is not required
form that might damage the internal con-
used in some parts of the world, which is a
to be ventilated as the timber structure is
struction of the roof.
naturally occurring material from Trinidad.
maintained at near internal temperature
In a mastic asphalt waterproofed warm
The material Asphalt is manufactured from bitumen
Mastic asphalt, used to form a continuous
conditions. In the cold roof configuration, as
roof, thermal insulation is set on top of the
waterproof covering on flat or sloping roofs,
(B) the waterproof layer is set directly onto
timber deck, with an asphalt layer on top of
has polymer additives in some types to pro-
the timber deck.Thermal insulation is set
this. A separation layer is set between the
vide stability at the relatively high tempera-
beneath the timber deck, in the voids
asphalt and the thermal insulation. A vapour
tures experienced when exposed to the
between the timber joists and air is allowed
barrier is set between the thermal insulation
effects of the sun, as well as providing flexi-
to circulate in the void to provide ventilation
and the timber deck. In the mastic asphalt
bility of the material at low temperatures,
MCR_ 130
Section 1:10. Low parapet wall
Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.
Mastic asphalt Plywood sheet or timber boards Separating layer Rigid thermal insulation Freestanding timber upstand Vapour barrier Softwood joists Dry lining/drywall internal finish Metal flashing Fascia board External wall Expanded metal lathing Rainwater outlet
Section 1:10. Rooflight
9 9 12
5
1
1
3
11
4
4 6
Section 1:10. High parapet wall
2
2
7
7
8
8
Section 1:10. Rooflight 11 9
12
1
1
1 5
5
3
3 4
4 6
2
2
6
7
7
8
8 8
which allows it to take up movements in the
timber deck is set to continue, particularly as
substrate. Asphalt is applied in a hot liquid
a result of additives which make the material
form on site, allowing it to form a homoge-
more flexible than was previously the case.
neous material at complex junctions such as
The essential difference for timber decks
Warm roof build-up Where timber boards are used instead of plywood sheet, the boards are usually tongued and grooved and around 19mm
at upstands, roof penetrations and changes in
between a mastic asphalt covering and those
thick to provide as rigid a substrate as possi-
level.The was used more commonly 25 years
in sheet materials is at upstands, where a
ble. Plywood decks are usually WBP grade
ago, and its popularity is being challenged by
separate upstand fixed to the roof deck
and at least 19mm thick. A minimum fall of
single layer sheet membranes, which have
rather than the wall, is often formed
1:50 (2%) is used to avoid ponding and to
greater strength, flexibility, a higher melting
between the roof and supporting wall in
keep the roof clear of standing water.
point and UV resistance. However, the use of
order to better accommodate the relative
Although completely flat roof decks are used
this material is set to continue, mainly a con-
lack of flexibility in the mastic asphalt.This is
for single layer membranes, this has not been
cealed membrane, but its use as an exposed
done where slight lateral movement in the
a part of the traditional use of exposed
membrane is discussed here since this appli-
roof deck is expected that cannot be
asphalt roof coverings, so the minimum 1:50
cation is much more common in timber con-
accommodated by the asphalt.The junction
fall is still observed as a rule. Falls are formed
struction. Mastic asphalt is laid on rigid sub-
between the top of the asphalt upstand and
by either tilting the supporting timber joists
strates, typically reinforced concrete decks,
the external wall is sealed by a metal flashing
beneath the deck, or setting flat or angled
but its use as an exposed membrane on a
fixed into the upstand or onto its surface.
strips, called firring pieces, on top of the
MCR_ 131
Timber 01 Flat roof : Mastic asphalt coverings
9 12 1 5 1 3 4
4
6 2
2 9
11
7
7
1
1
8
3 4 6
Section 1:10. Rainwater outlet
2
Section 1:10. Eaves
7
1 9
8
3 4
Section 1:10. 2-way drain outlet
6 2
Section 1:10. Expansoin joint 1
1 3
7
3 12
4
13
4
6
6 2
10
2
7 11
joists.The profiled shape of the firring pieces is dependent on the direction of the fall in
fibre underlay. Thermal insulation is usually provided to
an alternative insulating material. In order to achieve a U-value of 0.25 W/m2K, an insula-
relation to the direction of the structural
give a minimum U-value of 0.25W/m2K. In
tion thickness of 100mm - 150mm is
joists.Thermal insulation which is pre-formed
the warm roof configuration, the thermal
expected, varying slightly between the mate-
in the factory to a sloping angle, sometimes
insulation is of a type suitable for having hot
rials used.
called 'tapered' insulation, is offered by some
liquid-applied mastic asphalt laid onto it. As
manufacturers as an alternative method of
mastic asphalt retains a high temperature for
mal insulation layer in order to isolate the
creating a roof fall.
a comparatively long period after being laid,
asphalt from movement, mainly at joints, in
the insulation materials used are those which
the substrate or structural deck. It also helps
underside of the thermal insulation, on the
are both compatible and which maintain
to restrain the asphalt in cold temperatures.
warm (in winter) side. Roofing felt is com-
dimensional stability under such conditions.
Sheathing felt is used typically, loose laid with
monly used, or else a proprietary metal lined
Polyisocyanate foam materials and cork
laps around 50mm between sheets.
sheet with metal foil tape to seal the joints.
sheet are commonly used for this reason,
Asphalt is usually applied in two coats to
All laps and joints are fully sealed to avoid the
typically in a proprietary composite sheet
an overall thickness of around 20mm, set on
passage of water vapour through the barrier.
form as a composite of cork board with
a separating layer. In the exposed membrane
An alternative vapour barrier is of a layer of
polyurethane foam. Extruded polystyrene is
configuration the slope if the roof does not
asphalt, around 12mm thick, set on a glass
also used in the warm roof configuration as
exceed around 5°.When asphalt is laid
A vapour barrier is provided on the
MCR_ 132
A separating layer is laid onto the ther-
Section 1:10. High parapet wall
Section 1:10. Pipe penetration
9
12
1
1
5 3
4
6 2
2
9 11
7 12 1
5
8
3 4 6 2
Section 1:10. Low parapet wall 7
8 12 1
5
Details 3
11 6
4
2
7
8
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.
Mastic asphalt Plywood sheet or timber boards Separating layer Rigid thermal insulation Freestanding timber upstand Vapour barrier Softwood joists Dry lining/drywall internal finish Metal flashing Fascia board External wall Expanded metal lathing Rainwater outlet
directly onto concrete, in a concealed or
the asphalt surface with a proprietary adhe-
forming an upstand, sheathing felt is fixed to
inverted roof configuration discussed in the
sive. A single layer of 10mm - 14mm stone
the substrate, often a separate upstand fixed
Concrete chapter, the roof slope can go up
chippings are used as permanent surface
to the roof, as mentioned earlier. Expanded
to around 30°, also laid in two coats to an
protection for asphalt.The chippings are usu-
metal lathing, typically at 150mm centres,
overall thickness of around 20mm.When the
ally bonded to the asphalt after the asphalt
primed in bitumen, is fixed to the face of the
asphalt has been laid, sand is rubbed into the
has cooled, with a bitumen solution to pro-
sheathing layer, which provides a 'key' to
finished top surface while it is still hot in
vide only a limited bond.This allows the
which the asphalt will bond.Where the
order to break up the top surface of the
chippings to be removed easily at a later
upstand is formed in lightweight concrete
bitumen.This helps to reduce the effect of
date for repair and maintenance work.
block, the surface is faced with either a sand
gradual crazing of the surface caused by the effects of the sun.
cement render, or metal laths and sheathing
Upstands At upstands, where the asphalt is usually
Solar protection
felt is used as described. As with upstands in other materials, the
set vertically, or at a steep slope, the material
asphalt extends a minimum of 150mm
is laid in three coats.The first coat is very
above the finished roof level. If the upstand is
surface is usually applied to all exposed areas
thin in order to key in the substrate, then
formed directly against concrete blockwork,
with a solar reflective paint, stone chippings
two further separate coats are applied to
then the thickness is usually only around
or thin paving slabs which are bedded into
give an overall thickness of around 20mm. In
13mm. If the upstand to be waterproofed in
In warm roof construction, a protective
MCR_ 133
Timber 01 Flat roof : Mastic asphalt coverings 1 3 9
4 1
2
12 1
7
2 1
1
5
8
3
3
3 4
4 6 2
4 6
6 2
2 7
7
8
8
8
Section 1:10. Step in roof Section 1:10. Balustrade Section 1:10. Pipe penetration Section 1:10. Rooflight
1
1 12
3
1
3
3 4
4 6
6
6
2
2 7
10
7
8
8
8
11
asphalt is higher, then the material increases
25mm away from the upstand.This is to pro-
can result in a visually uneven appearance.
to 20mm, as used on the general areas of
vide a slot for additional asphalt in order to
When the asphalt edge is terminated by a
roof.The junction of wall and roof, or
strengthen the junction of vertical and hori-
gutter, a metal flashing can be set under the
upstand and roof, is formed with an angle fil-
zontal areas of asphalt. Upstands to
bottom of the asphalt. Alternatively, an alu-
let, where the material folds through two 45°
rooflights are formed to a height of 150mm
minium or GRP edge trim can be used.
folds. A single 90° internal fold can result in a
above the finished roof level.The asphalt is
failure of the material.The 45° angle fillet
continued up and across the top of the
asphalt upstand as shown in (C), built to a
formed also strengthens the junction, allow-
upstand.The asphalt is usually bedded in
height of around 50mm to suit the expected
ing it to absorb more movement between
expanded metal lathing fixed over sheathing
flow from the roof. An alternative detail is to
wall and roof deck. In masonry walls, the top
felt, as used with other forms of upstand.
stop the asphalt at the edge of the roof and
of the asphalt is turned into a chase, or horizontal groove, between blockwork courses, or is formed by a groove being cast into a
Verges can be formed by creating an
terminate in a metal strip so that the asphalt
Eaves and verges Trims to verges and eaves are formed
cannot be seen from below, but in practice it can be difficult to achieve a reliable seal
reinforced concrete upstand.Where a timber
with a GRP or aluminium trim in order to
between the asphalt and the metal trim. At
upstand is used which is separate from the
support the bottom edge of the asphalt.
the junction with a timber or metal-clad wall
main upstand (discussed earlier) the adjacent
Some installations use no trim at all, but the
set on the roof, an upstand is formed on the
thermal insulation on the roof deck is set
edge becomes vulnerable to damage and
roof a shown in (D) so that the upstand is
MCR_ 134
Section 1:10. Parapet
Section 1:10. Parapet
9
9 11 12
11
4 1
5
1 3 4
3 4
6
2
7
7
8
8
Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.
Mastic asphalt Plywood sheet or timber boards Separating layer Rigid thermal insulation Freestanding timber upstand Vapour barrier Softwood joists Dry lining/drywall internal finish Metal flashing Fascia board External wall Expanded metal lathing Rainwater outlet
supported by the roof only, in order to avoid
6
2
Saltwater Pavilion, Neeltje Jans, Holland. Architect: Oosterhuis Associates.
Penetrations
Gutters and rainwater outlets
the possibility of rainwater penetration as a
Penetrations through an asphalt covered
result of structural movement between the
roof are formed by extending the asphalt up
created within the timber deck since asphalt
roof and the wall.
by 150mm to create a collar round the
can be laid to suit a complex geometry
material.The top of the asphalt collar has an
without the need for joints in the material.
creating a low upstand in timber sections
apron flashing around it to protect the top
Where the gutter is formed as a parapet
which are fixed down to the structural tim-
of the asphalt. An alternative method of seal-
gutter at the base of the tiled roof, the
ber deck, as (E).The asphalt is dressed up
ing a roof penetration is to form a complete
asphalt is carried up over the tilting fillet of
across the top of the low upstand, bedded in
upstand around the penetration which can
the tiled roof.
expanded metal lathing with sheathing felt
be insulated to the top of the opening. An
beneath.The insulation is separated from the
insulated metal panel can then be mechani-
the outlet at the level of the structural deck.
timber sections in order to allow the asphalt
cally fixed and sealed, or bonded, to the duct
The asphalt is stepped down with 45° folds
to dip down to the level of the deck to pro-
or pipe creating the penetration. An addi-
down into the rainwater outlet, and the
vide additional strength to the joint. An edge
tional secondary seal, formed typically with
metal grating and cover is fixed down onto
trim is usually introduced on the edge of the
either EPDM or metal sheet, forms a sec-
this.The sheathing felt extends up to the
roof to terminate the asphalt and provide a
ondary seal to this penetration.
edge of the rainwater outlet.
A verge or fascia can also be formed by
Gutters can be formed to any shape
Rainwater outlets are formed by setting
visually crisp edge as seen from below.
MCR_ 135
Timber 02 Flat roof : Bitumen-based sheet membranes
Isometric view of assembly
9 7
1
1
10 3
2
3
4
4
5
2 6
5
Section 1:10. Rainwater outlet 6 6
Section 1:10. Low parapet wall
12
Section 1:10. Rooflight
Details 1. 2. 3. 4. 5. 6.
1
8 10
3 4
2
7. 8. 9. 10. 11. 12. 13.
1
1
Bitumen-based sheet Plywood sheet Rigid thermal insulation Vapour barrier Softwood joists Dry lining/drywall internal finish Metal flashing Timber upstand External wall Angle fillet Proprietary skirt flashing Rainwater outlet Paving bonded to bitumen-based sheet
3
3 4
2
5
5
6
5
This section discusses flat timber roofs that
branes applied to concrete decks are usually
increasing their flexibility and making them
use a bitumen sheet-based membrane as a
laid in hot liquid form and are reinforced to
thinner, requiring less material, which helps
waterproofing layer in a warm roof, which is
suit the specific conditions of folds and joints
to reduce their overall cost. Bitumen-based
a common combination. Although other
occurring within the structural deck. In this
membranes can also be used with concrete
membrane materials are used on flat timber
section the material is considered as an
and metal decks, and the principles here can
roofs as both warm and cold roofs, typically
exposed and visible material on a relatively
be applied in a similar way to those roof
formed in elastomeric and thermoplastic
lightweight deck.
deck types.
membranes, their application is discussed as
Bitumen sheet membranes are econom-
The material
Exposed Membranes in the Concrete chap-
ic, and are often used with timber roof
ter.The principles of detailing in that section
decks, which together provide an economic
can be similarly applied to timber roofs. Bitu-
roof design for relatively small-scale applica-
roll form in widths of around 1000mm, is
men-based sheet can also be used in 'invert-
tions, or designs with a complex geometry
black in colour, and is typically mixed with
ed roof', or concealed membrane configura-
of low pitched roofs, as is often used in
SBS (styrene-butadiene-styrene) polymers
tion as described in the Concrete Chapter
housing and in school buildings. Bitumen-
or with TPO (thermoplastic polyolefin) poly-
where the detailing is similar, but bitumen-
based membranes have developed over the
mers.The addition of these polymers raises
based sheet is generally less robust than the
past 25 years to compete with the newer
the melting point which ensures stability in
membranes described in that section. Mem-
elastomeric and thermoplastic materials by
hot weather as well as increasing the flexibili-
MCR_ 136
Bitumen-based sheet is manufactured in
Section 1:10. Expansion joint
Section 1:10. Low parapet wall
Detail A 7
7
3 1
10
8
1
1
10 3
3 4
4
2
2
2
5
5
9
5
6
6
Section 1:10. Low parapet wall with drain outlet 7
1
12
3
1
Pavilion, Burgundy, France.Architect: Dirk van Postel. 10
3 2
5
9 6
ty of the material at low temperatures (usu-
around 25 years.TPO-modified sheet can be
liquid form to seal the joints between the
ally in winter in temperate climates) and
exposed to the effects of the sun, requiring
boards, the bitumen setting to form a
enhancing the fire resistance of the material.
no additional solar protection, since the
smooth substrate. A vapour barrier is set
Bitumen-based sheet often has a glass fibre
material provides better UV resistance than
onto the prepared timber deck, the barrier
reinforced upper face to provide greater
older-type bitumen-based membranes. SBS-
being often bitumen-based as part of a pro-
dimensional stability and resistance to acci-
modified sheet is usually covered with stone
prietary system. Rigid closed cell insulation
dental damage, as well as a polyester rein-
chippings or solar reflective paint to protect
such as polyurethane is bedded in hot bitu-
forced core to increase tensile strength.
them from the effects of the sun.
men onto the vapour barrier to hold the
These sheet materials are typically around 4mm thick, depending on the proprietary system used. Even with these additives, bitu-
insulation securely in place. A loose laid per-
Roof build-up Where plywood is used to form the
forated isolating layer is set onto the thermal insulation which is used to allow the mem-
men-based sheet is slowly oxidised by heat,
structural deck of a timber roof, the joints
brane and thermal insulation to release gases
making the material gradually more brittle
between plywood boards are usually taped
into the isolating layer which are formed as a
which eventually results in cracks.The poly-
to provide a continuously smooth surface.
result of bonding the bitumen to the insula-
mer additives reduce this effect, particularly
On timber boarded decks, where this is not
tion.The bitumen-based membrane is then
the TPO additives which help to increase the
as practical a method, a thin layer of bitumen
bonded to the thermal insulation through
life of the material, which can now be up to
is laid onto the deck, applied typically in thick
the holes in the isolating layer.
MCR_ 137
Timber 02 Flat roof : Bitumen-based sheet membranes 7
1
7
1
10
1
3
3 4
2
9
5 9
6
12
1 3
Section 1:10. Low parapet wall 4 2
Detail B
Section 1:10. Door threshold 9
5
1 6
Section 1:10. Section 1:10. 2-way drain outlet
Detail C 1
Details 1. 2. 3. 4. 5. 6. 7.
Bitumen-based sheet Plywood sheet Rigid thermal insulation Vapour barrier Softwood joists Dry lining/drywall internal finish Metal flashing
8. 9. 10. 11. 12. 13.
Timber upstand External wall Angle fillet Proprietary skirt flashing Rainwater outlet Paving bonded to bitumen-based sheet
3 4 2
5
6
Solar protection Resistance to UV radiation is provided by
Fixing methods Bitumen-based membranes are fixed
spray applied to the substrate / structural deck. Bitumen-based sheet is laid on top and
either a coating of fine stone chippings or by
typically by either torching, bonding or
is rolled into place. Laps are sealed with
aluminium solar reflective paint applied to the
mechanical fixing methods.With torching, a
adhesive, but torching is sometimes used to
visible surface of the bitumen-based sheet. As
flame is used to melt an adhesive layer on
seal the laps of bonded membranes to allow
a result of providing this additional UV pro-
the underside of the sheet so that the mem-
them to be installed more quickly. Like elas-
tection, these coatings have the additional
brane adheres to the substrate. Sheets are
tomeric and thermoplastic membranes, the
benefit of reflecting heat, which has the effect
lapped by around 100mm to ensure a water
hot air welding of laps and joints is being
of reducing the surface temperature of the
tight seal.Torches are usually gas fuelled, sup-
introduced. A tool that provides hot air to
roof below that which would otherwise be
plied from a small canister as part of a hand-
the edge of the material is used that allows
the case. Solar reflective paint gives the roof
held tool, or are supplied from a large gas
the material to melt locally and be sealed
a metal appearance, which provides a visual
cylinder set onto the roof to a variety of
together.The use of bonding avoids the need
alternative to the characteristic black colour
tools, either hand-held or wheeled, for larger
for a flame that can damage adjacent finished
of bitumen-based sheet. Membranes can also
scale applications.
work.
be provided with a solar protection layer
In the bonded method, the sheet is
With the mechanical fixing method no
during manufacture as part of a proprietary
applied cold onto the substrate, the adhesive
adhesive is required, the membrane being
bitumen-based membrane system.
being either poured and spread in place or
fastened through the insulation layer into the
MCR_ 138
Section 1:10. Low parapet wall
Isometric view of assembly
7 7
1
3
1
10 4 3
9
4
2
2
5 5 6
6
Section 1:10. Expansion joint
Section 1:10. Eaves
Detail D
7
1 1
1
1
10
7
3
3
3 4
4 2
2
5
6
5
5
6
6
9
timber deck with disc-type fasteners. Laps
formed by either fixing the sheet to the ply-
can be made from any impervious and
between sheets are usually torch sealed to a
wood face of a timber framed upstand as
durable material. A pressed metal coping is
width of around 150mm. A vapour barrier,
(A), or to the face of the thermal insulation
shown in (B), overhanging on both sides to
with sealed laps, is laid onto the structural
as (B), depending on the configuration of the
provide added protection to the membrane
deck or substrate with the insulation set on
external wall.Where a timber roof deck
as it folds over the top of the wall. Upstands
top.The insulation is mechanically fixed to
meets a masonry wall, as (B) where a con-
to high parapet walls can be formed by ter-
the deck, with the bitumen-based sheet laid
crete block wall is clad in timber rainscreen
minating the membrane 150mm above the
onto the insulation.The mechanical fasteners
panels, the bitumen-based sheet is shown
finished roof level. Above this level the wall is
are fixed within the area of the lap in the
fixed to the face of the upstand.With a low
waterproofed with a different method, as
sheet through the insulation into the deck
upstand, the membrane continues up the full
shown in (C).Typically, concrete walls are
beneath. Mechanical fixings are covered by
height and extends across the top of the
waterproofed with bitumen paint and an
strips or are lapped over the top of the fix-
wall underneath the coping.The roof mem-
external panel-based finish, or render.The
ings, the laps being sealed by torching, then
brane is made continuous with the water-
top of the membrane is protected with a
pressed in place with a roller tool.
proof seal of the external wall, with the
folded metal flashing such as aluminium,
membrane as shown in (B) terminating
which is either bedded into a groove formed
against the bitumen paint finish of the exter-
in the joint between courses of blockwork,
nal face of the blockwork wall.The coping
or the metal strip is sealed against the wall
Parapet upstands Upstands in bitumen-based sheets are
MCR_ 139
Timber 02 Flat roof : Bitumen-based sheet membranes 7 11 1
1
1 3
3
3
1
10
4
4 2
2 5
5
5
6
6
6
Section 1:10. Step in roof
Section 1:10. Pipe penetration
Section 1:10. Rainwater outlet
Pavilion, Burgundy, France.Architect: Dirk van Postel.
12 1
1 3
3
4
10 2 5
6
with silicone if a concrete wall is used.The
pitched roof is formed by extending the
edge to form a drip, so that rainwater can-
vapour barrier continues up the full height of
base layer and membrane up 150mm above
not track up into the roof construction. A
the membrane. A 45° angle fillet is used to
the finished roof level, with an additional
metal drip is sometimes used to give a visu-
avoid turning the bitumen-based sheet
reinforcing layer to strengthen the junction.
ally sharper edge to the roof.The vapour
through a full 90° fold in a junction where
The roofing felt, or breather membrane, of
barrier beneath the thermal insulation is
significant structural movement can be
the tiled pitched roof extends down over
turned up so that it terminates against the
expected.
the top of this membrane to provide a com-
edge of the membrane drip to provide a
Upstands for perforations and movement
plete weather tight seal across the roof.The
continuous barrier. A metal flashing extends
joints are formed in the same way as other
bottom top row of tiles are kept clear of this
down from the vapour barrier and is lapped
upstands, but the membrane continues over
junction in order to avoid the possibility of
over the top of the tiling to provide a com-
the top of the upstand.Where an expansion
damage and to ensure that rainwater run-
plete seal from bitumen-based membrane
joint is formed, the membrane is separated
ning down the tiles cannot run back up the
the roof tiles beneath.The roofing felt or
on one side of the movement joint to open
gap between the tile and the roof mem-
breather membrane under the roof tiling is
and close as a result of structural movement.
brane by capillary action.Where a bitumen-
terminated against the underside of the
based membrane forms a waterproof cover-
upper timber deck.Where the membrane
ing to an area of flat roof at the top of the
meets a rooflight upstand the bitumen-based
pitched roof, the membrane is folded at the
sheet is taken over the top of the timber
Junction with tiled roof The junction of a flat roof and a tiled
MCR_ 140
Section 1:10. Pipe penetration
Section 1:10. Step in roof 1 3
7
4
2
5 1
1
1 3
10
5
3
3
6
4
4
2
2
5
5
5
6
6
Details 1. 2. 3. 4.
5. 6. Bitumen-based sheet Plywood sheet Rigid thermal insulation 7. 8. Vapour barrier 9.
Softwood joists Dry lining/drywall internal finish Metal flashing Timber upstand External wall
6
10. Angle fillet 11. Proprietary skirt Section 1:10. Balustrade flashing 12. Rainwater outlet 13. Paving bonded to bitumen-based sheet
Isometric view of assembly
7
13 1 4
8
3
3 4
2 2 5
6
5 6
upstand to form a continuous seal with the
behind the drip to ensure that all rainwater
are formed with a low upstand that prevents
vapour barrier on the inside of the building,
running off the edge of the eaves is collected
rainwater from running over the edge of the
where required, as well as the vapour barrier
by the gutter, and that no water is allowed to
verge.The membrane is continued up over
beneath the thermal insulation.The rooflight
run behind the gutter and down the face of
the top of the upstand. A GRP or metal
is fixed to the top of the sealed upstand, typ-
the wall below, where staining can occur
edge trim is set at the edge to terminate the
ically with a continuous timber glazing bar or
from the dust washed off the flat roof.The
membrane as well as forming a drip at the
metal strip that seals the gap between glaz-
vapour barrier under the thermal insulation
top of the external wall. An additional sealing
ing and upstand.The edge of the rooflight
is continued to the edge of the roof to
strip of membrane is lapped over the edge
typically includes a drip to avoid water run-
ensure that the timber sections forming the
trim to provide a complete water tight barri-
ning back up into the joint between upstand
edge of the eaves are kept dry and ventilat-
er, as well as providing reinforcement to
and rooflight.
ed within the roof void beneath.The thermal
strengthen the joint.The vapour barrier
insulation is kept continuous between wall
extends up the side of the timber upstand
and roof to avoid thermal bridging that
but it is not necessary to extend it to the
reduces the thermal insulation value of the
edge of the roof due to the extra layer of
external envelope.
bitumen-based membrane that provides a
Eaves and verges The eaves detail shown in (D) is formed with a folded drip formed in the same way as described for the junction with the top of a pitched roof.The gutter is tucked up
Verges typically extend along the edge of
full seal.
shallow slopes of bitumen-based roofs, and
MCR_ 141
Timber 03 Pitched roof :Tiles 7 8 7 1 5
1
5
10 9
3 9
10
13 11
4
6
11
3
4
6
12
13
14 14
15
Section 1:10. Plain tiles. Eaves
15
Detail B
Section 1:10.Interlocking tiles. Monopitch ridge Section 1:10. Plain tiles. Eaves
Detail E
Section 1:10. Plain tiles. Abutment 15
12
Details 1. 2. 3. 4. 5. 6. 7. 8.
13
1
5
3
7
9. 10. 11. 12. 13. 14. 15. 16.
Plain tile Interlocking tile Softwood battens Softwood counter battens Roofing felt Gutter Softwood rafter Vapour permeable membrane Thermal insulation Vapour barrier Softwood joist Metal flashing Ventilator Fascia board External wall Ridge capping
16
2 5
3
7 15
Clay tiles for roofs are most commonly made
tional clay tiles in both shape and variety of
against rainwater penetration as well as pro-
from clay or concrete. In the clay type natural
colour, but large interlocking tiles are avail-
tecting the roofing felt from direct wind-
clay is mixed with additives such as quartz,
able in sizes that are difficult to achieve in
blown rain, the effects of the sun, as well as
mica, iron oxide and crystalline aluminium
clay. In common with clay tiles, concrete plain
protecting the felt from accidental damage.
oxide. Clay tiles are fired in a kiln at around
tiles are used in roof pitches down to 35°
Many tile shapes and profiles are available
1100°C to make the material both rigid and
above the horizontal. An advantage of con-
which have been developed from historical
resistant to moisture penetration. Plain tiles
crete tiles over clay tiles is that some con-
examples.The design life for tiled roofs in
are used on pitched roofs ranging from verti-
crete interlocking tiles can be used for pitch-
both clay and concrete types is around 30
cal tile hanging to pitches as low as around
es as low as 12.5° above the horizontal.
years but they are actually expected to last
35° above the horizontal. Interlocking tiles,
Both tile types are fixed to timber bat-
for around 100 years.
with grooves and complex laps can be used
tens set horizontally, that is, at right angles to
in down to a minimum pitch of 22.5° above
the direction of the slope.The battens are
the horizontal. Concrete tiles are made from
fixed onto roofing felt, which forms a second
aggregate and Portland cement which are
line of defence and full weathertight barrier
the most common being around 260mm x
mixed together and then cured in tempera-
to the roof.The roofing felt is set on timber
160mm.Tiles are lapped by a minimum of
ture-controlled chambers in the factory.Their
rafters (sloping timbers) or full timber truss-
around 35mm on their top edge, called the
appearance tends to imitate those of tradi-
es.The tiles provide the first line of defence
'head lap', when hung vertically, and are head
MCR_ 142
Plain tiles Plain tiles are made in a variety of sizes,
Section 1:10. Interlocking tiles.Eaves
Detail F
Nara Centennial Hall, Japan. Architect: Arata Isozaki
2
8 4
3
5
9 6
12
10
15
Section 1:10. Interlocking tiles.Valley gutter
Section 1:10. Interlocking tiles. Monopitch ridge 15 12
4
2
12
3 8
14
13 2
12
3 7
6
10
9
8
4
10
15
lapped by a minimum of around 65mm
tiles that lap over it.Tiles have two nibs
action.Tiles are also lapped at their sides,
when hung on any slope down to 35° above
(brackets) on their underside which hook
again with grooves set into the tiles, usually
the horizontal.The maximum head lap for all
over the battens to both support the weight
on both faces of the tiles that lap. Again rain-
conditions is around 90mm, so that tiles are
of the tile and to align them on the battens,
water is drained down these grooves onto
always lapped with three tiles set over one
which are set out accurately to ensure that
the centre of the tile below, which has the
another, as (A).Tiles are butted up to one
the required arrangement of tiles is
overall effect of draining the tile on all four
another on their sides, with joints staggered
achieved.
sides.This interlocking of tiles, together with
over one another to avoid rainwater penetration by draining water that penetrates the outer tile onto the middle of the tile
the provision of drainage grooves, avoids the
Interlocking tiles Interlocking tiles in both clay and con-
need for three tiles to always lap one another, as is required for plain tiles. As tiles lap
beneath, where it runs on down the roof.
crete are also made in different profiles and
only at their edges, only one tile thickness is
With the maximum head lap, the smallest
sizes, with a typical size of around 400mm x
required, with any water that passes through
size of visible tile is around 170mm x
300mm.This tile type has a longer head lap
the joint from windblown rain being drained
160mm, giving a shape to each tile approxi-
of around 100mm which accommodates
down the roofing felt to the bottom of the
mating to a square.Tiles are fixed to battens
grooves in the bottom of the top tile.These
roof.The typical 100mm head lap and 30mm
with nails fixed through two holes at the top
grooves serve as drips to avoid the passage
side lap give a typical visible tile size of
of the tile, which are covered by the two
of rainwater up through the tile by capillary
300mm x 270mm which, like plain tiles, has a
MCR_ 143
Timber 03 Pitched roof :Tiles
Section 1:10. Interlocking tiles.Verge
Details 1. 2. 3. 4.
15
12 1 5
3
9. 10. 11. 12. 13. 14. 15. 16.
9 7 10
Section 1:10. Plain tiles. Abutment
Detail P
Section 1:10. Interlocking tiles. Abutment
5. 6. 7. 8.
Plain tile Interlocking tile Softwood battens Softwood counter battens Roofing felt Gutter Softwood rafter Vapour permeable membrane Thermal insulation Vapour barrier Softwood joist Metal flashing Ventilator Fascia board External wall Ridge capping
2
3
4
8
7
10 15
Detail N
15
Section 1:10. Interlocking tiles. Abutment
Detail Q
12 15
10
2
3
8
12 2
13
9
9 4
3 4
8 10
7
9
10
square-like size.This is often not perceived
timber and the thermal insulation. In recent
as at its edges for this to work. In practice,
due to the rolled or wavy profiles typical of
years it has become more common to use a
most cold roofs are still ventilated at the
traditional designs, but is visually dominant in
vapour permeable membrane or 'breather'
ridge and at the eaves even when a breather
flat, modern designs. Like plain tiles, the inter-
membrane as the underlayer to the tiling
membrane is used as an underlay to the
locking types have nibs on their underside to
instead of waterproof roofing felt.This is
tiling.These principles apply equally to
hang and align the tile, and are fixed with
done to avoid ventilating the roof void,
monopitch roofs as (C) and roof spaces
nails which are usually larger than those used
which can become very damp in temperate
which are divided.
for plain tiles in order to secure the larger
climates during winter. Any vapour in the
sized tiles.
roof void escapes through the breather
filled with thermal insulation in order to
membrane, but in practice the ceiling has to
allow the internal space of the roof void to
be completely sealed to avoid any vapour
be used, as (E). As with the cold roof, a
Ventilation Like flat roofs, pitched roofs are formed
In the warm roof, the sloping rafters are
passing from the space below into the roof
vapour barrier is set between the thermal
as either warm roofs or cold roofs. In the
void.While a vapour barrier between the
insulation and the internal dry wall lining. A
cold roof as (B), horizontal joints are insulat-
thermal insulation and the dry wall lining
vapour permeable membrane is set on the
ed, and the void is ventilated to ensure that
beneath is standard, in all roof constructions,
outside face of the sloping rafters as an
any condensation forming in the roof void
the barrier must be completely sealed
underlay to the tiling. If the insulation com-
can escape, which avoids damage to both the
around roof hatches, pipes and ducts as well
pletely fills the void between the rafters, then
MCR_ 144
Section 1:10. Plain tiles. Monopitch ridge
Detail C
Section 1:10. Interlocking tiles. External fold
Section 1:10.Vertically hung tiles
16 2 3 1
3
1 9
4
10 12
3
3
2
15
5
4
3
1 7
7 8 12
15
Section 1:10. Interlocking tiles. Internal fold
Section 1:10. Plain tiles.Verge
Detail H
1 3
5
12 2
7
7 15
8
Plan 1:10.Vertically hung tiles at internal and external corners 4 3 1
3
9 3
1
10
this breather membrane serves to allow
them through the underlay.
configuration.
Eaves
ventilator is set beneath the underlayer as
moisture trapped within the construction to escape. If the thermal insulation does not fill the void, and is set against the internal dry
In the cold roof version the proprietary Both plain tiles and interlocking tiles are
shown in (F). Fresh air is allowed to flow into
lining, then the void between the insulation
terminated at their base with a gutter. In
the ventilator set beneath the bottom tile
and the breather membrane is ventilated at
order to maintain a constant pitch of tiles
and is released into the roof void without
the ridge and at the eaves.Where a breather
down to the gutter, the bottom row of bat-
affecting the thermal insulation of the roof at
membrane is used, the cavity between the
tens is raised up on a wedge-shaped timber
ceiling level, which is continuous between
outside face of the membrane and the tiles
profile called a tilting fillet.This allows the
wall and roof. In the warm roof version, a
is increased from 25mm to 50mm to allow
underlay to meet the underside of the bot-
ventilator set between the bottom tile and
the air within the void to move more freely,
tom tile, and drain both rainwater running
the felt underlay introduces air into the void
ensuring that vapour being released to the
down the tiles as well as any moisture run-
between the tile and the breather mem-
outside can be dispersed easily.The
ning down the underlay, into the gutter. A
brane.The thermal insulation either contin-
increased gap if formed by battens set per-
ventilator, typically in PVC-U, is set between
ues to the fascia board, then returns hori-
pendicular to the tiling battens, called
the bottom tile to ventilate either the roof
zontally back form a continuity with the wall
counter battens, which are set in the direc-
void in a cold roof, or the cavity between
insulation, or alternatively the wall insulation
tion of the rafters, and are fixed down to
the underlayer and the tiles in a warm roof
continues vertically until it reaches the slop-
MCR_ 145
Timber 03 Pitched roof :Tiles 16 2 2
8 3 1
1
8 3
6 12
3
7
9
5
7
7 10
9
Section 1:10. Plain tiles. Ridge
9
Detail A
Section 1:10. Interlocking tiles. Ridge
10
Section 1:10. Interlocking tiles.Valley gutter
DetailG
Details 1. 2. 3. 4.
16
5. 6. 7. 8.
16 2
3
4
2
9. 10. 11. 12. 13. 14. 15. 16.
8 3
9
10
9
8
10 7
Plain tile Interlocking tile Softwood battens Softwood counter battens Roofing felt Gutter Softwood rafter Vapour permeable membrane Thermal insulation Vapour barrier Softwood joist Metal flashing Ventilator Fascia board External wall Ridge capping
7
ing insulation set between the rafters. In the
void in a cold roof configuration.Where the
beneath.The ridge tile is fixed in the same
second version, the void forming the fascia
batten cavity is ventilated the cavity is sealed
way in the warm roof version, with a PVC-U
and soffit immediately beneath it is in 'cold'
across the ridge. Air is allowed to pass
ventilator set below the ridge tile.
roof configuration and is required to be ven-
through a gap between the bottom of the
tilated in order to avoid damp, stagnant air
ridge tile and the roof tile immediately
from damaging the timbers.
beneath, the gap being formed by the PVC-
Verges Verges, or gable ends, are closed with a
U ventilator.The ridge tile itself is mechani-
sand cement mortar seal between the
cally fixed to a ridge batten which is secured
underside of the tiles and the fascia board
back to the counter battens beneath with
beneath, as (H). Metal clips, usually in stain-
tiles are either bedded in a sand cement
metal clips, usually in stainless steel.Where
less steel, are used to restrain the edge tile.
mortar, as (G), or are dry fixed with metal
the complete roof void is vented to the out-
Proprietary systems of interlocking tiles
screws, typically stainless steel, where a rapid
side in a cold roof, a gap of around 10mm in
often have special verge tiles, as (J), where
installation is required. For ventilated ridges,
the underlay is formed at the ridge.The
the tile forms a straight vertical face.The
proprietary fixings usually made in PVC-U
underlay is turned up the side of the top
verge tiles are clipped together to hold them
with ventilation slots are used to ventilate
row of battens on each side of the ridge to
in place to resist wind uplift.The void
either the batten cavity between the under-
ensure that rainwater is not blown up the
enclosed by the timber fascia board and sof-
lay and the tiles, in a warm roof, or the roof
batten cavity and down into the roof void
fit board beneath is usually ventilated in
Ridges Where a sealed ridge is required, ridge
MCR_ 146
Sections 1:10. Plain tiles. Hips
Detail K
Sections 1:10. Plain tiles.Valleys
1
Detail M
1
6
5 5
7 7
1
1 5 5
7
7 6 12
Section 1:10. Interlocking tiles.Verge
Nara Centennial Hall, Japan. Architect: Arata Isozaki
Detail J
2 3 8 7 12 7
9
14 10
15
order to keep it dry.The vents, as at the
often made using the same method as at the
eaves, have bird mesh or insect mesh to pre-
ridge in order to suit the individual shape of
vent the voids from being used as nesting
the tile used.
areas.
Valleys are formed in the same way, with
Abutments Where a tiled roof meets a vertical wall at the ridge, a proprietary ventilator is set onto the top tile, as (N), which is clipped
either folded tiles or mitred tiles.When a
onto the tile itself. A gap between the verti-
large amount of rainwater is collected in the
cal wall and the top tile is maintained to
valley, a full gutter can be formed by intro-
allow the free passage of air, while the gap
with either specially folded hip tiles or by
ducing a metal or GRP strip, as (M).The
between ventilator and wall is closed with a
cutting the tiles to create a mitred corner.
edges of the gutter are folded up the adja-
metal flashing that is set into the vertical wall
Specially folded hip tiles, as (K) form part of
cent battens and are made continuous with
and folded over the top of the PVC-U venti-
manufacturers' ranges of tiles, but usually
the felt underlay.The gutter is usually sup-
lator, to which it is bonded or mechanically
they suit only 90° corners in plan, and only
ported by timber boards or plywood sheet
fixed. A side abutment requires no ventila-
certain roof pitches. More complex folds in
set between the rafters as shown in (M). An
tion and the metal flashing folds into the gap
the roof can be formed with cut tiles that
additional layer of underlay is sometimes set
below the top tile as (P) or is formed into
meet at the fold line, with the open joint
beneath the gutter as a second line of
the slope of the interlocking tile as (Q).
being closed by a metal flashing beneath the
defence against rainwater penetration at
fold line, as (L). Hips in interlocking tiles are
folds and junctions in the gutter.
Hips and valleys Hips and valleys in plain tiles are formed
MCR_ 147
Timber 04 Pitched roof : Slates
Section 1:10.Valleys 1
7 1
7
2
2 11
5
9
6
8
8
9 11 1 4
4
2 11 5
Section 1:10. External fold
7
Detail B
Section 1:10. Internal fold
6
6
Detail A
2
Section 1:10.Valleys
1
6
4
1 5 6
11 11
1
8
4 5
7
11
6
9
Roofing slates are made in either natural cut
performance in reducing rainwater penetra-
the lap between the slates.This improved
stone, as reconstituted stone or as fibre
tion. Fibre cement slates are cement-based
jointing allows the material to be used in a
cement tiles which imitate the appearance of
imitations of natural slates which are more
single thickness rather than as two layers.
the natural material. All these slate types are
economic than the natural material.
made in a similar size to tiles, at around
Natural slate is sorted into at least three
All these slate types can be used in roof
groups on site, based on the material thick-
450mm x 350mm, but are also available in a
pitches from vertically hung to usually 22.5°
ness, which varies in the splitting of the nat-
wider range of sizes, from 600mm x 300mm
above the horizontal. All slate types require a
ural material.When fixed, slates used on any
down to 400mm x 200mm, depending on
head lap (discussed in the previous section
course (row of slates) are of similar thick-
the manufacturer. Natural slate is used as a
on tiles) ranging from 60mm to around
ness.The thickest slates are used at the base
flat material that is fixed in the same way as
120mm depending on the roof pitch. Both
of the roof, and the thinnest are used at the
tiles, as discussed in the previous section.
natural slate and fibre cement types are laid
top of the roof, with slates in between vary-
Reconstituted slates are made from typically
in a way that maintains a minimum thickness
ing progressively from thick to thin. Fibre
50% to 60% recycled waste slate (from the
of two layers of slate to ensure a weather
cement slates are of constant thickness and
quarrying of slate) which is mixed with resin
tight roof covering. Reconstituted slate is
do not require any sorting on site.
and glass fibre reinforcement, then pressed to
often formed with profiled edges that inter-
shape. Reconstituted slate are usually made
lock to reduce the possibility of capillary
principles set out in the previous section on
with an interlocking profile to enhance their
action from rainwater being drawn up into
tiled roofs, with both warm and cold roof
MCR_ 148
The ventilation of slate roofs follows the
Section 1:10. Monopitch ridge
Section 1:10. Eaves
Details 1. 2. 3.
Slate Softwood battens Softwood counter battens Roofing felt Gutter Softwood rafter Vapour permeable membrane
4. 5. 6. 7.
6
15
1 10
8 2
4
1
8. 9. 10. 11. 12. 13. 14. 15. 16.
Thermal insulation Vapour barrier Softwood joist Metal flashing Ventilator Fascia board External wall Ridge capping Flexible pipe
9
4 14
6
12
2
5
13
14
Section 1:10. Ridge with vent extract
Detail C
Tateyama Museum of Toyama, Japan. Architect: Arata Isozaki & Associates. 15
12
1 4
2
6
16
configurations being detailed in the same
underlay beneath. In (B) the external fold is
usually in PVC-U as part of a proprietary
way.The detailing of eaves, ridges, verges, hips
formed by projecting the upper slate out
system.The connector is closed around the
and valleys follows the same principles of
slightly to form a drip, ensuring that rainwa-
base of the roof vent and is sealed where it
rainwater drainage, ventilation and thermal
ter does not run back up the metal flashing
penetrates the underlay to ensure that rain-
insulation as set out in the section on tiled
beneath, which is positioned in the same
water cannot find its way into the roof void.
roofs.
way as in (A).
A ventilator set into the pitch of the roof, as (D), can have a flexible duct connected to it
Roof folds Changes of roof pitch that form a fold
Vents
in the same way.
Extract points for mechanical ventilation
Monopitch ridges
line are formed by reducing the lap at the
ducts can be integrated into a vent at the
head of the tiles, or head lap, to a minimum.
ridge as well as on the general area of
In (A) the roof pitch forms an internal fold,
pitched roof without requiring a projection
is formed with a specially formed ridge slate
where the upper tile is butted up to the
above the roof that would be visible from
or clay tile.The ridge slate or tile is mechani-
lower tile. A metal flashing is set beneath the
below.The ridge vent In (C) uses a similar
cally fixed to the timber structure beneath
upper slate and is lapped over the outer face
vent as that required for a ventilated ridge,
to either allow the ridge to be ventilated or
of the lower slate to ensure that rainwater is
as described in the section on tiled roofs.
closed against the sloping slates on one side,
directed down the slope and not onto the
The top of the flexible duct has a connector,
and a timber board on the vertical face.
As with apex ridges, a monopitch ridge
MCR_ 149
Timber 04 Pitched roof : Slates 15 2 12
12 1 1
2
6
4
4 6 6
7 8
Section 1:10. Ridge 9
Section 1:10.Ventilators
15
Detail D
Sections 1:10.Verges 1
11
4
11
13
1
1
4 6
2
6 14
14
4 14 6
Section 1:10. Monopitch ridge Section 1:10. Expansion joint 1
1
6
Section 1:10. Eaves
2
1
11
7
8 9
Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.
Slate Softwood battens Softwood counter battens Roofing felt Gutter Softwood rafter Vapour permeable membrane Thermal insulation Vapour barrier Softwood joist Metal flashing Ventilator Fascia board External wall Ridge capping Flexible pipe
MCR_ 150
6 11 5
14
Sections 1:10. Ridges
Section 1:10. Abutment
Detail J
15 14
12
1
7
2
11 4 8 6
1
9
2 6 4
Sections 1:10. Ridges 15
12
Sections 1:10. Hips
1
4
15
6 7
8
9
1
6
4
15
15
12
11
2
1
6
4
8
7
1
6
9
Sections 1:10. Eaves
4 7
2 1 10
9
2
1
8
8 9
12 6 6
11
11 5
13
14
12
5
13
14
MCR_ 151
Timber 04 Pitched roof : Slates
14
11
1
1
11 2
4
4
13 6 6 14
Section 1:10. Abutment
Section 1:10.Verge Section 1:10. Abutment
Detail H
Section 1:10.Valley gutter
Detail K
7
14
1
2
14 11
8 11 12 9
12
5
6
2
1 6 4
Dormer windows
the slates, as in (E), to ensure that ventilation
of the roof and is sealed against the vertical
of the vertical cladding is maintained at the
face of the wall.Where brick is used, as (H)
cheeks, of a dormer window, are shown in
top of the cheek. Air is also allowed to enter
and (J), the flashing is returned into a joint
(E).The supporting structure for the slates is
the batten cavity at the base of the wall, as
between brick courses.
typically timber framed, with insulation set
(F). At the corners of the vertically-hung
between the timber studs (vertical framing
slates, as (G), slates form internal and exter-
way, with a metal tray folded up the under-
members) in warm roof configuration. Hori-
nal corners by butting the slates together
side of the slate, as described in the section
zontally-set softwood battens are fixed onto
from each side to form a corner, and setting
on tiled roofs.The vertical face of the gutter
vertically-set battens which are fixed back to
a metal flashing beneath to ensure the conti-
where it meets the adjacent wall, as (K) is
the underlay or breather membrane.The
nuity of weather tightness at the corner.
sealed with a flashing set over the top of the
Slate cladding on the vertical faces, or
vertically-set battens, or counter battens, ensure that moisture is allowed to run freely down the membrane or underlay as well as
gutter to provide a complete weather tight
Abutments Abutments at the side of a pitched roof,
encourage natural ventilation behind the
as (H), and at a monopitch ridge condition
slates. Slates are hung from the battens.The
as (J), are formed by covering the joint
edge of the low pitched roof of the dormer
between wall and roof with a metal flashing
window has its fascia board set forward of
which is fixed over the top of the first slate
MCR_ 152
Valley gutters are formed in the same
seal.
Plan 1:10.Vertically hung slates at internal corner
Detail G
Tateyama Museum of Toyama, Japan. Architect: Arata Isozaki & Associates.
14 1
Section 1:10. Detail F 8
8 1
14
1
2
Plan 1:10.Vertically hung slates at external corner
Detail E 1
2 3 13
11 8
8
9
2 14
1
8
1
Section 1:10. Dormer window
8
Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.
Slate Softwood battens Softwood counter battens Roofing felt Gutter Softwood rafter Vapour permeable membrane Thermal insulation Vapour barrier Softwood joist Metal flashing Ventilator Fascia board External wall Ridge capping Flexible pipe
11
1
12
2
3
7
8
6 9
MCR_ 153
Timber 05 Pitched roof : Metal
13 1
8
1 4
Section 1:10. Parapet verge
Details : Standing seam roof 1. 2. 2
4
3. 4. 5. 6. 7.
Standing seam sheet Fibre quilt thermal insulation Vapour barrier Timber beam/joist Folded metal gutter Folded metal drip Fascia board
8. 9. 10. 11. 12. 13. 14.
External wall Metal sheet fixing bracket Soffit board Metal supports Ridge piece Metal flashing Parapet flashing
Isometric view of assembly
1 9
6
1 9
11
13
5
6
5
13
4
7
Section 1:10. Eaves
4
10
Detail A
House,Wye River, Australia. Architect: Bellemo & Cat.
Section 1:10.Valley gutter Section 1:10. Ridge
Detail B
12 1 9
4
2 3
MCR_ 154
Section 1:10. Abutment
Section 1:10.Verge
13
13
1 9
1 4
10
4 11
2
8
3 3 4
8
2 3
Section 1:10. Parapet verge
13 1 9
8 11 4
4
2 3
Standing seam cold roofs
(ridge or abutment), with verges and para-
sheet and sealed against the sheet.This
Standing seam roofs are discussed in the
pets at the sides of the roof remaining
ensures that rainwater running down the
Metal chapter as sealed, insulated roof cover-
sealed.
gutter cannot enter the roof void, while air can still pass into the roof void.
ings in a warm roof configuration.When used in the cold roof configuration with a pitched timber roof, the standing seam roof is venti-
Eaves and valley gutters Eaves are ventilated by leaving a gap
Ridges and abutments
lated, with thermal insulation provided at ceil-
between the top of the fascia board sup-
ing level.
porting the gutter and the underside of the
ically 100mm between the metal sheets, as
standing seam roof sheet. A metal angle is
(B).The gap at the ridge is covered with a
metal deck is set onto a timber roof of truss-
fixed in front of the opening as (A) to avoid
folded metal ridge capping which is fixed to
es and purlins. At ceiling level, thermal insula-
rainwater being blown through the opening
the sheets beneath. A narrow gap is main-
tion quilt is set between the ceiling joists
into the roof void.Valley gutters are formed
tained between the ridge sheet and the
(horizontal members). A vapour barrier is set
in a similar way, with a gap formed between
standing seam sheet in order to provide
beneath the insulation, positioned on the top
the gutter tray and the metal sheet to pro-
constant ventilation along the ridge. Alterna-
surface of a dry lined wall beneath.The roof
vide ventilation to the roof void.The metal
tively, PVC-U ventilator blocks are added at
void is ventilated at the lowest point (eaves
tray has an upstand at the edge which is
centres along the ridge, and the joint
or parapet gutter) and at the highest point
lapped up to the underside of the metal
between the ridge and the roof deck is
In this build-up a ventilated standing seam
Ridges are formed by creating a gap, typ-
MCR_ 155
Timber 05 Pitched roof : Metal
14
1 13
1
9
9 11
13
6 7 4 5 2
2
4
7
4
3 3
8
8
Section 1:10. Eaves
Section 1:10.Verge
Section 1:10. Penetration
Detail C
Section 1:10. Penetration
Detail D
Detail E
13 13
1
5 9
1. 2. 3. 4. 5. 6. 7. 8. 9.
11 4
4
Details : Standing seam roof
2
10. 11. 12. 13. 14.
Standing seam sheet Fibre quilt thermal insulation Vapour barrier Timber beam/joist Folded metal gutter Folded metal drip Fascia board External wall Metal sheet fixing bracket Soffit board Metal supports Ridge piece Metal flashing Parapet flashing
3
sealed. Abutments are formed in a similar way to ridges, with a folded metal sheet that
1 9
5
11 4
4
2
3
Penetrations Penetrations are formed in a way which
Metal tiled roofs Metal tiles are increasingly being used for
is fixed to the roof sheet on one side and is
forms a gutter around the opening in the
roofs due to the flexibility of the roof pitch
sealed against the adjacent masonry/con-
roof as (D) and (E). In (E) rainwater runs off
and tile lap that can be formed economically
crete wall or parapet, typically with an addi-
the roof into the gutter, at the edge of the
for individual projects. Copper and zinc are
tional metal flashing which projects from
upstand, which is set at the level of the adja-
commonly used, with their characteristic
within the depth of the wall.Verges are
cent roof sheets.Water is directed around
patina that is suitable for both walls and
formed with a metal clip which provide a
the sides of the upstand and back onto the
roofs. Metal tiles are fixed in the same man-
closer to the edge sheet as (C), with an
roof sheeting below. Penetrations in roofs
ner as clay tiles and slates, with battens and
additional metal coping set over this to pro-
are positioned so that the standing seam
counter battens set onto a bitumen- or
vide a second line of defence against rainwa-
joints between roofing sheets are clear of
polymer-based waterproof underlay. Eaves
ter penetration.
the sides of the opening in the roof to
and parapet gutters are formed in the same
ensure that rainwater can run freely around
way as standing seam roofs, with ventilation
the sides of the upstand to the roof opening.
slots provided to ensure that air can pass through the roof void. Metal tiles are either flat like slates, or alternatively are made from profiled sheet, which imitates the appear-
MCR_ 156
Section 1:10. Monopitch ridge
15
16 25
19 17
21
20 22
27
15
Details :Tiled roof 15. Metal tiles 16. Softwood battens 17. Vapour permeable membrane 18. Gutter 19. Softwood rafter 20. Ventilation void 21. Thermal insulation 22. Vapour barrier
23. 24. 25. 26. 27. 28. 29.
Softwood joist Metal flashing Soffit board Fascia board External wall Ridge piece Ventilator
17 24
20
16 19
18
22
21
27 27
Section 1:10. Eaves
24 15
ance of traditional tiled roofs made from
17
curved or profiled tiles.Their appearance is very different from profiled metal sheet, with its continuous long lengths of sheeting.The
18
24 19
short metal tiles, lapped over one another, can easily take up complex geometries with
20
a pattern of joints and laps that clearly show 21
the form of the roof.
22
Ridges and verges are usually made from folded metal sheet and are individually designed and fabricated for a building project. An advantage of metal sheet tiles over clay tiles is that tiles and edging pieces can be individually designed for each project while remaining economic, since metal can
Section 1:10.Valley gutter
be folded without the need for moulds which are required for clay tiles and slates.
MCR_ 157
Timber 05 Pitched roof : Metal
15 16
19 20
17
26
21
22 House,Wye River, Australia. Architect: Bellemo & Cat. 27
Section 1:10. Monopitch ridge 15
16 20 21
22
17
Details:Tiled roof 15. Metal tiles 16. Softwood battens 17. Vapour permeable membrane 18. Gutter 19. Softwood rafter 20. Ventilation void
19
18
27
Section 1:10. Eaves
15
17
15
20
24
19
21 22
18
29
15 25 17
16
20
27
Section 1:10. Eaves
MCR_ 158
19
21
22
Section 1:10. Abutment
Section 1:10.Verge
Section 1:10. Abutment 21. 22. 23. 24. 25. 26. 27. 28. 29.
15 16 17
21
19
Thermal insulation Vapour barrier Softwood joist Metal flashing Soffit board Fascia board External wall Ridge piece Ventilator
27
24
15 16
19
17 21
20
22
Section 1:10. Ridge 28
29
29
15
17
16 19
20
23
21 22
Section 1:10.Verge
15
17 19 26
19
21 22 25
27
MCR_ 159
5 PLASTIC (1) GRP rooflights Eaves and upstands Verges Abutments Sliding roof panels (2) GRP panels and shells Smaller panels and shells Larger panels and shells
MCR_ 161
Plastic 01 GRP rooflights
Key plan and elevation. Typical small rooflight layout 5
5
1
1
2
1
1
2 9
1
Sections 1:5. Small rooflight ridge and eaves 7
5
4
2 5 1
1
10
1
9
3
Section 1:5. Small rooflight verge Sections 1:5. Small rooflight panel to panel junction
Sections 1:5. Small rooflight panel to panel junction 4 5
5
4
1
1
5
2
7
4
1
2
7
3 2 1 3
4
5
3 1
1
9
2 9 3
Glass reinforced polyester (GRP) is used in
age. GRP is a composite material formed by
set into the void is usually bonded to the
the form of thermally insulated panels to
reinforcing flexible fibreglass mat (or fibres)
outer GRP facing sheets to provide true
form translucent rooflights which are robust
with thermosetting polyester resins that pro-
composite action between the GRP skin and
and economic when compared to an equiv-
vide high tensile and compressive strengths.
the insulated core. Like metal composite
alent glazed rooflight with double glazed
The material is not combustible, making it a
panels, GRP panels increasingly have a ther-
units. GRP rooflights use the principles of
suitable material for rooflights as well as an
mal break introduced into the framing to
metal composite panels which are combined
opaque roof cladding material.While GRP
reduce the possibility of condensation form-
with greenhouse glazing framing to provide a
rooflight systems do not usually achieve the
ing on the underside of the panel in temper-
lightweight, highly thermally insulated and
high levels of resistance to wind blown rain
ate climates as well as to improve the overall
economic rooflight.Where glazed rooflights
of internally drained and ventilated curtain
thermal insulation value of the rooflight.
sometimes need an additional layer of solar
walling systems, they are robust and eco-
Thermal breaks are usually made from an
shading, or use solar performance glass to
nomic, making them ideal where translucen-
extruded polymer that has a much lower
reduce the effects of the sun, GRP rooflights
cy is required rather than the transparency
thermal conductivity than aluminium, and are
provide a more economic solution.The
provided by glass panels.
bonded to the extrusion in the manner of
advantages of GRP over glass are its
Rooflights are made from GRP sheet
glazed curtain walling or are clipped to it and
strength, lightness and flexibility, as well as
which is bonded to an aluminium carrier
secured in place by self tapping screws that
the material's high resistance to impact dam-
frame around its edges.Thermal insulation
hold the pressure plate in position.
MCR_ 162
Section 1:5. Large rooflight ridges.
Detail A
Section 1:5. Large rooflight ridges.
5
5
4
2
1
1
Section 1:5. Large rooflight eaves
Detail F
4
1
2
3 1
9
3
3
2
9
9
4 10
Section 1:5. Large rooflight abutment . Detail K
Details 1. 2. 3. 4. 5.
Translucent and insulated GRP roof panel Thermally broken aluminium framing Inside Outside Pressure plate
6. 7. 8. 9. 10.
Adjacent masonry/concrete wall Folded metal cover strip EPDM strip Supporting structure Concrete upstand
4
7 6
Bus Station, Lugano, Switzerland. Architect: Mario Botta 2
1
3
9
In small rooflights, up to around a
section forms the support to the panels on
slope sometimes have pressure plates with
3000mm span, GRP composite panels
all four edges, with an extruded aluminium
lapped joints, as (B), in order to avoid water
require no additional support, while those of
pressure plate being used to hold the panels
building up on the upper side of the joint
greater span use an additional aluminium or
in place on the outer face of the GRP pan-
and being unable to run over the joint.The
steel frame beneath to support the compos-
els. Most support frames are now internally
lap is formed by setting an aluminium strip
ite panels over the greater span. Panel sizes
drained and ventilated to provide a second
or extrusion, as (B), under the bottom edge
vary with the proprietary system and with
line of defence against rainwater penetra-
of the panel which laps over the top of the
the individual rooflight design.Typical panel
tion.The outer seal is provided by an extrud-
panel below.This combination of glazed cur-
sizes range from around 400mm x 800mm
ed EPDM gasket clipped into the aluminium
tain walling (or greenhouse glazing) tech-
to 800mm x 3000mm. GRP rooflight panels
extrusion. Proprietary tapes are also used,
niques and composite metal panel tech-
use a lightweight framing system rather than
but are more dependent upon good work-
niques provides a method of construction
a lapped junction or raised edges to provid-
manship on site than gaskets which are fixed
for translucent rooflights which is visually
ing a standing seam type joint used in metal
to the pressure plate in factory conditions.
lightweight with slender joint lines.
composite panels.These make their appear-
Pressure plates for panel joints running
In addition to these standard junctions
ance more refined, since the framing is very
down the slope, as (A), are set over the joint
which form part of proprietary systems, pan-
visible in translucent GRP panels, unlike their
between the panels in the manner of glazed
els are jointed with folded metal sheet, as
metal equivalent. An extruded aluminium T-
curtain walling. Joints running across the
(C), where unusual junctions are to be
MCR_ 163
Plastic 01 GRP rooflights 7
4
1
1
1
9 3
2
2
Section 1:5. Large rooflight ridge.
Detail D
Section 1:5. Large rooflight panel to panel junction
1
4 5
Section 1:5. Large rooflight eaves.
Details
Detail E
Section 1:5. Large rooflight upstand at base
1.
Translucent and insulated GRP roof panel 2. Thermally broken aluminium framing 3. Inside 4. Outside 5. Pressure plate 6. Adjacent masonry/ concrete wall 7. Folded metal cover strip 8. EPDM strip 9. Supporting structure 10. Concrete upstand
1
2
2
1
9 1 3 2 9 10
formed. In (C) a folded metal sheet is fixed
inner joint between panels, as is the case
over the top of the upper panels, ensuring
elsewhere, because the thermal insulation
that rainwater runs down the panel, and
cannot be set within the drainage cavity
as (E), an intermediary aluminium extrusion
forms a drip where it is fixed to the top of
where it would both impede the passage of
or folded sheet is used to form the junction.
the vertical panel. An inner metal sheet is
the small amounts of water that would be
An outer EPDM or extruded silicone seal is
bonded to the junction of the panels to pro-
drained in the internal cavity, as well as lose
used as an outer line of defence against rain-
vide an inner seal and vapour barrier. An
its thermal insulation properties due to the
water penetration at the junction with the
alternative detail is to fill the void with ther-
absorption of water.
GRP roof panel. Drainage slots formed in
mal insulation, as (D), in order to reduce the
Eaves and upstands When a rooflight terminates in an eaves,
In (D) a ridge flashing is formed in the
the bottom of the aluminium closer piece
risk of condensation forming on the under-
same way, with a metal sheet fixed to the
drain away any water that passes through
side of the panel in temperate climates.This
upper face of the GRP panel frame and a
the outer seal.These drainage slots also take
is typically used in a wider than typical joint
membrane waterproofing layer beneath. Any
away any water to the outside from the
where the provision of a thermal break is
rainwater that penetrates the outer seal is
drainage channels within the joints between
usually difficult to achieve. A second line of
drained either at the ends of the ridge or
panels that run down the slope of the roof.
defence against rainwater penetration is pro-
down the joint between the panels that run
The GRP panel beneath the closer piece
vided by a membrane set immediately
down the slope of the roof.
that forms a vertical part of the rooflight is
beneath the metal flashing rather than on the
MCR_ 164
formed by setting the panel behind a vertical
Section 1:5. Large rooflight monopitch ridge.
Detail C
Section 1:5. Large rooflight internal fold.
Detail B 4
5 1
7
2 2 4 1 3 1 2
Section 1:5. Large rooflight external fold 3 5
1
4 2 2 1 1
9 3
Section 1:5. Large rooflight base.
Detail G
Section 1:5. Large rooflight external fold 1 9
4 5
1 2
2
2
3
7
1
10
aluminium strip that forms a lapped joint
supporting frame. A metal closer piece is
upstand beneath is sealed with a metal flash-
over the top of the panel, avoiding the possi-
used to provide a continuous edge support
ing set forward of the vertical face of the
bility of rainwater passing through the joint.
to the GRP panel as well as a weathertight
upstand.This allows water to drain out of
The gap between the aluminium closer and
seal. A waterproof membrane is bonded to
the ventilated channels in the joints that
the GRP panel is sealed with either an
the outside of the closer piece and is
form the second line of defence against rain-
EPDM gasket, a proprietary tape, or a sili-
secured to the upstand below, typically
water penetration. A waterproof membrane,
cone sealant. A metal gutter is fixed to the
formed in reinforced concrete.The closer
typically EPDM, is bonded to the bottom
metal closer if required, but this is usually
piece is thermally insulated and is sealed on
edge of the metal frame surrounding the
exposed unless it forms part of a fascia, such
its inner face with a thin folded aluminium
GRP panel and is sealed against the water-
as the curved eaves used in profiled metal
strip that serves both to retain the thermal
proofing layer of the upstand, providing a
roofing, for example. In smaller rooflights the
insulation in place and as a vapour barrier.
continuous seal from the surrounding area
rainwater typically runs off onto the sur-
The visible width of the inner closer strip
of flat roof up to the rooflight. A thermal
rounding area of flat roof.
usually matches that of the adjacent alumini-
break in the framing of the GRP composite
um joints between the panels and is visible
panel ensures a continuity in the thermal
minium closer piece as used at eaves, or with
within the building, as (F). In (G) a GRP panel
insulation from upstand to GRP rooflight.
a metal flashing, where the GRP panel is sup-
is fixed to a supporting frame.The gap
ported on an additional steel or aluminium
between the bottom of the panel and the
Upstands are formed either with an alu-
MCR_ 165
Plastic 01 GRP rooflights
Section 1:5. Abutment.
Key plan. Small curved roof layout
Detail L
4
1 5 3
Section 1:5.Verge.
6
Detail J
4
5 7
10
1
1
Section 1:5. Small rooflight upstand at base
7 3
2
5
4
1 1
1
Section 1:5. Small rooflight panel to panel junction
1 4
5
1
9
1
3
3
Section 1:5. Small rooflight ridge Section 1:5. Small rooflight ridge Bus Station, Lugano, Switzerland. Architect: Mario Botta
Key plan. Small facetted pitched rooflight layout
4 5
1
1
3
Verges
with mineral fibre quilt type thermal insula-
connected structurally, as (L), the membrane
tion, which has the flexibility required to fill
usually has an extra curve of material
are formed with an aluminium flashing that is
the irregular-shaped voids between GRP
between the panel and the wall to allow for
bonded, or mechanically fixed and sealed, to
panels. An additional aluminium angle is used
structural movement between wall and roof.
the metal edge frame to the side of the GRP
at the junction of the inner face of the pan-
The outer line of defence formed by the
panel forming the sloping panel, and to the
els to provide an additional seal and vapour
metal flashing is set onto the membrane and
top of the triangular-shaped vertical end
barrier.
is folded up the vertical face of the wall. An
The gable ends of sloping GRP rooflights
additional metal flashing is used to cover the
panel. In (H) the sloping panel extends slightly forward of the vertical panels to give a thin
Abutments
top edge of the metal flashing where signifi-
edge to the roof, while in (J) the roof termi-
Where a GRP rooflight is set against a
cant structural movement is expected, as in
nates in a sharp edge, with a folded alumini-
vertical wall in another material, such as rein-
(K), the outer metal flashing being fixed into
um sheet or angle closing the gap between
forced concrete or concrete block, a metal
a continuous groove or horizontal joint line
the panels. As with other panel to panel junc-
flashing is used as in (K) and (L). Beneath the
in the concrete or masonry wall to provide
tions, a waterproof membrane is set on the
metal flashing, a waterproof membrane is
a weathertight seal to the top of the flashing.
underside of the outer metal flashing as a
bonded to the edge of the GRP panel and is
second line of defence against rainwater pen-
folded up the abutting wall to which it is
etration.The void between the panels is filled
bonded.Where wall and rooflight are not
MCR_ 166
Section 1:5. Small rooflight panel to panel junction
Small curved rooflight layout
Section 1:5. Eaves
5
4
4
1
1
1 2 4
3
5
2
1
3
1
2
3 10
Section 1:5.Verge.
Detail H
4
Details
1
1. 2. 7
2
3.
Translucent and insulated GRP roof panel Thermally broken aluminium framing Inside
Section 1:5. Ridge
3
4. 5. 6. 7. 8. 9. 10.
Outside Pressure plate Adjacent masonry/concrete wall Folded metal cover strip EPDM strip Supporting structure Concrete upstand
9 1
4
1
1
2 9
10
3
Sliding roof panels The lightweight nature of GRP rooflight panels is being used increasingly in sliding
opening windows, which are usually higher
cavity within the rooflight frame, draining out
than those of fixed glazed rooflights.
through holes in the bottom of the alumini-
Panels can move either side to side in
um profile onto the roof below. An inner air
panels that allow a rooflight to be opened at
the manner of sliding doors, or vertically in
seal, either polymer foam based or similar to
different times of the year.Typically up to
the manner of sash windows.The same prin-
the outer gasket seals, is provided on the
around 40% of panels in a rooflight are
ciples of fixing and waterproofing joints are
underside of the GRP panel.These general
opened by sliding them over adjacent fixed
used regardless of the direction of move-
principles of sliding panels will no doubt be
panels, in relatively modest electrically oper-
ment of the panels. In (M), one side of the
developed to suit more complex geometries
ated systems.Where larger-scale glass
horizontally sliding panel has an upstand,
of openable panels over the next 10 years.
rooflight panels are difficult and expensive to
while the other three sides are set into a
The pop-out type sliding doors that move
become openable due to the weight of the
slot. In the slot connection, the outer (upper)
outward before sliding, together with hinged
glass and the complexity of their seals, GRP
seal comprises EPDM or silicone-based gas-
panels, will make this rooflight system more
rooflight panels are easier to slide, with seals
kets, usually in a 'flipper' section that allows
generally applicable to large-scale applica-
being provided by lapped joints with EPDM
the aluminium framing to slide in and out of
tions of all building types.
or extruded silicone seals in the manner of
the housing on one side, and to slide on the
sliding doors. Opening panels are sealed to
other two sides. Any rainwater that pene-
the levels of air infiltration associated with
trates the outer seal is drained away in a
MCR_ 167
Plastic 02 GRP panels and shells
Bus Station, Hoofddorp,The Netherlands. Architect: NIO architecten 1
1
1
1
5 5
Section 1:5. Panel to panel junction 1
1 3
5
5
3
3
5
3 1 1
1
1
Section 1:10. Panel to panel junction Detail E Section 1:10. Perimeter
Sections 1:5. Panel to panel junction Detail C
3 1 1
1
5
1
1
Where glass reinforced polyester (GRP) rooflights, discussed in the previous section
Smaller panels and shells Smaller shells, as shown in generic exam-
of the wheel are held in place by T-sections that, in plan, form concentric circles.This
on rooflights, are made as panels which are
ples (A1) and (A2), consist of a set of seg-
'bicycle wheel' form is supported near its
joined to form translucent rooflights, opaque
mented panels which are bolted together to
perimeter by a metal ring beam that is set
GRP panels can be made as monolithic, self-
form a roof shell of approximately 7.0
immediately above the glazing beneath the
supporting shells, usually made from panel
metres diameter.Type (A1) is supported by
GRP roof.The ring beam is supported by
segments which are brought to site and bolt-
an additional frame, while (A2) is a self-sup-
posts that are fixed to the roof deck
ed together.The segment sizes of GRP shells
porting GRP shell.
beneath.
are made in sizes which are suitable for
In (A1), GRP panels are supported by a
The metal frame is clad in prefabricated
transportation by road, usually set upright on
light metal frame beneath.The frame com-
GRP panels which are bolted to the support
a trailer.The shells can then be lifted by crane
prises steel or aluminium T-sections which
frame on their internal face in order to avoid
into place as a completed assembly, which
are welded together to form a structure that
visible fixings. Panels are made with an outer
makes them quite different from roof struc-
supports the complete outer skin.The frame
skin of GRP around 5mm thick, with an
tures in other materials.
has curved members that radiate from the
overall panel depth of around 45mm for the
centre at the top to the edge and from the
panels sizes shown of 3500mm long and
centre at the lowest point of the structure,
1800mm wide.The GRP panels are stiffened
back to the perimeter.The radiating 'spokes'
by concentric ribs, around 120mm wide, as
MCR_ 168
Plan and section 1:50. Generic examples A1 and A2
Detail B
2 3
3
3
5
Details
5
1. 2. 3. 4.
GRP shell panel GRP outer cladding panel GRP structural rib GRP thin panel with honeycomb core 5. Mild steel or aluminium frame 6. Mild steel or aluminium truss 7. GRP flashing 8. Waterproofing membrane 9. Metal fixing bracket 10. Thermal insulation
shown in (B).The long edges of panels do
that conceals the joint lines. Finally, a paint
external face in the same way as example
not require thick ribs, and these are around
finish is applied, usually as a spray, to give a
(A1). A different method for forming the top
10mm thick as shown in (C). Panels secured
smooth and reflective finish.Where pigments
of example (A2) is shown in (E).Where
with bolts which are fixed through the metal
are applied to the top coat, or 'gel' coat, in
panel segments converge at the top of the
support frame into reinforcing ribs at the
the factory, a more limited range of colours
shell, a separate centre panel is used to cre-
edges of the GRP panels. Joints between
is available.Thermal insulation is set on the
ate a smooth external finish. A central exter-
GRP panels are formed by butting panels up
underside of the shell, being bonded to the
nal panel avoids the difficulty of bringing up
to one another and sealing the gap between
inner face of the GRP panels in order to
to 16 panels together at a single point which
the panels.The seal is formed in a continu-
achieve continuity of insulation.
would make it difficult to achieve a smooth
ous step profile on the long edges of each
Generic example (A2) uses glass fibre
panel that creates a continuous groove at
ribs that form part of the shell to provide
transition from one side of the shell to the other. In the example shown, a shadow
the joint between panels.The groove is filled
integral structural stability to the shell. Panels
groove is set around the joint between the
with a lamination of glass fibre and resin to
are around 200mm deep, as (D), and are
central panel and the segments in order to
fill the groove to the level of the top of the
bolted together to form a self-supporting
avoid any misalignment between segmented
panels.The external face of the GRP is then
GRP shell. Ribs are made in solid GRP in
panels from being visible.The perimeter joint
ground smooth, usually by a hand-held
order to allow them to be bolted together
of the panel can be filled and sealed using
grinder, to achieve a uniform, smooth surface
easily. Panels are joined and sealed on their
the method described earlier, with additional
MCR_ 169
Plastic 02 GRP panels and shells Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
GRP shell panel GRP outer cladding panel GRP structural rib GRP thin panel with honeycomb core Mild steel or aluminium frame Mild steel or aluminium truss GRP flashing Waterproofing membrane Metal fixing bracket Thermal insulation
1
1
Plan and section 1:200. Generic examples B1 and B2
grinding required on site to ensure a smooth
panel, but the drip reduces the amount of
ished in GRP to create the negative shape of
finish.
water that runs down to the glazing below.
the panel being formed. GRP panels are fab-
The underside of the shell is mostly set
The curved glazed units beneath the
ricated by first applying a release agent to
internally behind curved glazed units set near
roof shell are set into a recessed slot at the
the mould to allow the finished panel to be
the perimeter of the roof.The internal part
panel joint.The recess avoids the possibility
removed easily, then thermosetting polyester
of the shell on its underside, has the same
of a weakness in the seal that could result in
resins are applied to the face of the mould,
panels with the same finish, but without any
using a butt joint between shell and glazing.
with flexible fibreglass mat being laid into the
thermal insulation, which is typically set
The edge of the double glazed unit is sealed
resin, usually with rollers.The process of fab-
around the outer edge of the shell in order
completely around the junction with the
ricating GRP panels is very labour intensive,
to keep temperatures within the void close
shell, typically with silicone.
but requires no expensive equipment, mak-
to those within the building. Close to the
Both the cladding panels of (A1) and the
ing panel production a craft-based technique
edge of the shell, on the underside, the joint
self-supporting shell of (A2) are made using
rather than an industrial process.When the
between the top panel which curves around
the same manufacturing process. Panels are
panels are released from the mould they are
the edges, and the adjacent panel under-
made in a mould, usually from a single seg-
trimmed along their edges and ground
neath, has a groove formed along the joint to
mented panel type to form a complete
smooth where necessary. An alternative
serve as a drip.Windblown rain will still be
rooflight. Moulds are usually made from ply-
method is to apply a mixture of resin and
pushed along the underside of the soffit
wood to create the shape and are then fin-
glass fibre particles as a spray directly into
MCR_ 170
Section 1:10. Junction at base
3
10
2
6
4 1
3
the mould.The mixture is applied to a thick-
outer screen.The inner shell serves as the
ness of 3mm to 5mm depending on the
loadbearing structure, it being easier to
panel size required.
install panels with a pre-finished internal sur-
by bringing the panel segments to site indi-
face since no further access is required for
vidually, due to their size.The panels are then
finishes work on its internal face. Conse-
bolted together on site, on the ground.The
quently, no scaffolding or access platforms
joints are then formed on the finished face,
hemispherical dome of 20 metre diameter is
are required inside the building to install and
either internal or external. Finally, the shell is
constructed as a self-supporting shell. In (B1)
finish the rooflight.The outer skin of GRP
lifted by crane into position on the roof as a
a shell is made from GRP only, while in (B2)
cladding panels is fixed using a lightweight
complete item.The flexibility and lightweight
the dome has structural stability provided by
crane that lifts the outer segmented panels
nature of GRP makes this possible, which
an external steel or aluminium truss.The
into position.The construction method can,
avoids the need for scaffolding and access
truss might be used to support a decorative
of course, be reversed so that an outer shell
equipment at roof level. An alternative
outer screen or a lighting system to illumi-
with a factory-applied finish can be installed
method, where no space is available on site
nate translucent panels, for example.
as a pre-assembled item that requires no
for assembly, is to create a platform beneath
further work externally. GRP cladding panels
the shell inside the building, where the roof
shell, with integral GRP structural ribs, is clad
can then be applied to the internal face of
can be assembled in place. However, the
with GRP panels that form a weathertight
the shell from inside the building, but this the
sanding and grinding operations required to
Larger panels and shells In generic example (B1) and (B2) a
In example (B1) a loadbearing inner
more difficult construction method. The structural shell is usually assembled
MCR_ 171
Plastic 02 GRP panels and shells
6
2 1 2
2
2 2 2
2 2 2 1 2
Plan and section 1:100. Generic examples B1 and B2
make the inner face of the shell smooth and
They are also made from GRP, filled with
vides an outer seal against rainwater pene-
continuous, and ready for painting, usually
mineral fibre insulation or injected foam to
tration.The layer is given a further protec-
requires the in-situ constructed solution to
provide thermal insulation, with overall sec-
tion and visual screen provided by outer
be in an enclosed space to avoid GRP dust
tion sizes of around 200mm wide x 300mm
cladding panels. Like the inner shell, the
particles from spreading around the building.
deep, as shown in detail (F).The horizontally-
outer cladding is made from 15mm thick
set ribs span a maximum of around 450mm
composite panels, stiffened by GRP ribs
with an inner wall around 15mm thick made
at the base of the shell, deceasing in size until
around 100mm deep x 200mm wide.These
as a thin composite panel.The panel is
they reach the top of the shell, as shown in
outer segmented panels are bonded to the
formed with two outer skins of GRP, 2 -3mm
(G). GRP ribs are also set vertically on the
inner shell with resins or with silicone, and
thick, with an inner core made from
edges of the panels, filled with thermal insu-
sealed with silicone at their joints to form a
polypropylene-based honeycomb sheet.The
lation but made as solid GRP where panels
continuous outer skin. Small amounts of rain-
honeycomb core provides a rigid reinforcing
are fixed together with bolted connections,
water that might penetrate the outer line of
layer to the outer skins of GRP that give
as (H).
defence are drained away down the outer
The inner shell in example (B1) is made
them a flat, smooth appearance.This inner
The shell is thermally insulated with min-
GRP skin of the inner shell.While it is easier
skin is reinforced by structural ribs that form
eral fibre or foam-based insulation set in the
to provide a continuous smooth finish in a
an integral part of the panel, and are set hori-
voids between the ribs.The outer face of the
smaller shell, in larger examples it is more
zontally at approximately 1000mm centres.
shell is covered with a GRP skin that pro-
difficult to avoid visible surface irregularities
MCR_ 172
Plan 1:10. Panel to panel junction, example B2 Detail J
Section 1:10. Panel to panel junction, example B2
Section 1:10. Panel to panel junction, example B1
Detail F
4
4
10
6
10
6 2
3 2
3
3
1 1
4
2
4 1
Plan 1:10. Panel to panel junction, example B1
Detail H
2
10
4
2 10
3
3
1
1
Bus Station, Hoofddorp,The Netherlands. Architect: NIO architecten
Section 1:10. Junction at base
Detail K
4 1
3 3 7
on larger shells. For this reason, visible joints
In both examples (B1) and (B2), the
shell where it is protected by another GRP
are usually preferred in larger-scale GRP
junction at the base of the shell is treated as
cover strip, concealed from view by internal
shells.
an upstand.This allows the shell to be set a
finishes.
In generic example (B2), an additional
minimum 150mm above the adjacent roof
metal truss in either mild steel or aluminium
level without the need for complex junctions
is fixed at the panel joints to provide struc-
between roof slab and shell.The base of the
tural stability.The GRP ribs within the panels
shell has a continuous GRP flashing bonded
forming the inner shell are reduced to
which also serves as a fixing plate onto the
20mm thick ribs, as (J). A metal plate is set
concrete upstand, as (K).The base plate is
between the adjacent panels, with the joint
set on levelling shims to take up the con-
being sealed with silicone. Like example (B1),
struction tolerances in the height of the con-
an outer skin of GRP cladding panels pro-
crete upstand.The waterproofing membrane
vides an outer line of defence against rain-
of the adjacent roof is taken up to the top of
water penetration. Panels are mechanically
the upstand and is lapped under the GRP
fixed to a continuous metal plate forming
flashing, as (K). An additional waterproofing
part of the truss, the panel being sealed
membrane may extend to the inside of the
against the plate with silicone seal, as (J).
inner shell and up the internal face of the
Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
GRP shell panel GRP outer cladding panel GRP structural rib GRP thin panel with honeycomb core Mild steel or aluminium frame Mild steel or aluminium truss GRP flashing Waterproofing membrane Metal fixing bracket Thermal insulation
MCR_ 173
6 FABRIC (1) ETFE cushions Cushions Air supply The material Fabrication Durability Performance in fire (2) Single membrane : Cone-shaped roof Fabric roof principles Fabric types Comparison of types Thermal insulation Acoustics Durability Performance in fire Condensation (3) Single membrane : Barrel-shaped roof Membrane roof fabrication Membrane roof edges Suspension points Membrane folds
MCR_ 175
Fabric 01 ETFE cushions 2
1
1
2
2
2
5
1
Isometric view of junction of clamping plates
Arteplage, Neuchatel, Switzerland. Architect: Groupe Multipac.
Section 1:5. Junction of clamping plates
2 4 3
7 5 5
Fabrics used as roof membranes have the
tion of inflatable fabric roofs.
Cushions
advantage of being light in weight, strong in
Although large scale self-supporting
tension and durable, and have the ability to
inflatable roof structures are in use, particu-
mum of two layers of ETFE sheet which are
be cut to different shapes and joined togeth-
larly for covering sports stadiums, they
set back to back to form a flat panel and are
er economically, which is difficult to achieve
remain structurally stable only while air is
sealed at the edges.The void within the
so easily with metal and is very expensive to
being supplied to the structure. If the air
cushion-shaped panel is inflated with air to a
achieve with curved glass. Roof membrane
supply is interrupted, the complete roof
pressure of between 200 Pascals and 700
fabrics are used in tension structures, either
structure deflates. In smaller scale applica-
Pascals, depending on the cushion size and
by stretching the material, or 'prestressing'
tions, air-filled cushions remain in place when
the manufacturer's proprietary system, to
the membrane, between structural supports
the air supply fails or is switched off when
provide structural stability to the panel.The
or, alternatively, by supporting the material
used as non-loadbearing panels.This type,
increased air pressure stretches, or 'pre-
pneumatically in inflated structures.The use
where ETFE sheet is used to make panels
stresses', the outer membranes, giving ETFE
of fabric membranes in prestressed roofs is
formed as air-filled 'cushions', provides highly
cushions their characteristic curved shape.
discussed in the next two sections on single
transparent, lightweight and resilient roofs
The cushions are held in place by clamps
layer fabric membranes.This section consid-
that have thermal insulation values similar to
that form a frame around the cushions in
ers ETFE cushions, also called 'pillows' or
those of double glazed units.
the manner of glazed rooflights.The clamping
'foils', which are the most common applica-
MCR_ 176
ETFE cushions usually consist of a mini-
frames are then supported by a mild steel
Section 1:10. Opening smoke vents with insulated gutter
Detail F
Section 1:5. Clamping plate assembly
1
1
2
1
1
4 3
5
8
Details
5. Supporting structure 6. Plastic air supply tube 7. Main air supply tube 8. Insulated metal lined gutter 9. Metal flashing 10. ETFE cushion with contours shown for clarity
1. 2.
ETFE cushion Extruded aluminium clamping plate 3. Extruded aluminium retaining profile 4. Plastic edge bead to fabric membrane Plan 1:10. Junction of clamping plates
5
Section 1:5. Clamping plate assembly 2 1
1
3
Plan 1:10. Clamping plate with air supply pipes
1
Detail C
2
1
1
2
2
1 3 5
6 1 5 7
structure formed typically as box sections or
breaks at the panel perimeter to partially
are connected to a larger pipe that supplies
tubes. Cushions typically have three layers
overcome this loss of thermal insulation.The
the air to all the cushions either side of a sin-
that form two chambers, as (A).The two
overall U-value can be reduced by forming a
gle structural support.This main pipe is also
chambers are linked by a hole formed in the
wide gap between the two outer mem-
usually made from plastic and can be con-
middle (flat) membrane in order to allow air
branes, as (B), to provide a consistently wide
cealed within the supporting structure, being
to pass to both chambers from a single air
air space within the cushion.Thermal insula-
only up to a diameter of around 60mm.The
supply, and to ensure that the air pressure in
tion performance can also be improved by
air supply, which maintains the air pressure
both chambers remains equal.This three
increasing the number of air chambers with-
within the cushions at a constant level, is
layer cushion provides a U-value of around
in the cushion by adding further layers of
supplied by electrically powered fans with air
2.0 W/m K, which is similar to a double
ETFE membrane.
filters (to avoid the passage of dust), as used
2
glazed unit used in glass roofs. Cushions made from two layers of ETFE sheet are also used but the thermal insulation performance
in mechanical ventilation systems within
Air supply Air is supplied to cushions from rubber
buildings.The humidity level of the air is usually controlled to avoid the possibility of con-
is reduced considerably.Thermal insulation
pipes or flexible plastic pipes that are con-
densation forming within the cushions. Once
performance is reduced at the perimeter of
nected to the underside of the cushion near
the ETFE cushions have been inflated, air is
the cushion where its thickness is reduced to
the clamping assembly, as shown in (C). Pipes
supplied to the cushions for only around 5-
a thin edge. Some cushions have thermal
are usually of around 25mm diameter, and
10 minutes per hour to compensate for loss
MCR_ 177
Fabric 01 ETFE cushions
Section 1:10. Junction with adjacent roof 2 1
1
1
2
3 8 3 5 5
Section 1:10. Junction of clamping plates
Section 1:10. Junction at base
Detail B
1
Section 1:5. Junction with gutter 3
5
1
2
2 9 3
5
Section 1:10. Junction of clamping plates
Detail A
1 2
8
1 2
5
of air pressure from leaks from cushions or
ensuring that ventilation levels within the
Teflon) which is made by extrusion as a
from air supply pipes.
building are sufficiently high to avoid this
sheet material.Thicknesses vary but 0.2mm
If air pressure within the cushion is lost as
occurring, and that levels of relative humidity
is a common thickness of material for ETFE
a result of damage to one of the outer mem-
are suitably controlled.Where condensation
cushions, allowing them to be very light in
branes or from loss of air pressure in the
is still a risk, condensation channels are fixed
weight at around 350g/m² for this thickness
supply pipe, the cushion deflates to its flat-
to the underside of the cushion clamping
of sheet. Heavier gauge sheet at 0.5mm
tened shape. As wind pressures are applied
assembly as shown in (D), similar to that
thickness weighs around 1000g/m². Inner lay-
to the external face of the cushion, the outer
used for glazed rooflights. In most cases the
ers of ETFE sheet that provide separate
skin will deflect either inwards or outwards
temperature of the air supplied to the cush-
chambers within the cushion are often made
as a result of the positive or negative pres-
ions is similar to that of the internal space
from 0.1mm thick sheet.The material is also
sures.This does not usually cause damage to
immediately below the roof, so condensa-
used for its high level of transparency, with
the cushions before the air supply is restored.
tion does not usually occur on the underside
95% light transmission, and its durability
Some manufacturers' systems have one-way
of the cushion.
when compared to other fabric materials,
valves to prevent loss of air pressure from the cushions back to the supply pipes. Condensation on the underside, or internal face, of ETFE cushions is avoided by
MCR_ 178
with a life expectancy of 25-35 years, based
The material ETFE (ethylene-tetra-flouro-ethylene) is a polymer similar to PTFE (marketed as
on visual criteria. In order to provide translucent areas of roof (or façade) using the same material, a white coloured translucent
Section 1:5. Junction of clamping plates
Detail D
Isometric view of junction of clamping plates
1
2
1
4
3
10 10
6 5
6
5
7
Details 1. 2. 3. 4. 5.
Section 1:10. Junction of clamping plates
1
ETFE cushion Extruded aluminium clamping plate Extruded aluminium retaining profile Plastic edge bead to fabric membrane Supporting structure
6. 7. 8. 9. 10.
Plastic air supply tube Main air supply tube Insulated metal lined gutter Metal flashing ETFE cushion with contours shown for clarity
2
2
1
1
5 5
sheet is manufactured which provides
The amount of solar shading provided can
the use of a thin ,stretched, membrane
around 40% light transmission. ETFE does
be varied by allowing the middle layer to
material.
not provide a barrier to the passage of UV
move as a result of changing the air pressure
light, making it ideal for use in buildings
within the cushion.The middle layer moves
where extensive planting is displayed, though
either outwards or inwards to increase the
the translucent white sheet has greatly
overlap of the printed screen of dots that
the workshop but can be assembled on site
reduced UV light transmission. Solar shading
has the effect of varying the amount of solar
to suit project conditions.The material is
can be provided by a pattern of dots printed
shading provided.
manufactured in rolls of considerable length
onto the surface of the ETFE cushion, with a
The sound absorption of ETFE cushions
Fabrication ETFE cushions are usually fabricated in
but of a width of around 1.5 metres. For this
reflective silver colour being a popular
is low, so that sound travels easily through
reason, ETFE cushions are often made with
choice, though other colours and patterns
the material.While this can be an advantage
spans in widths of around 3.0 metres to 4.0
can be developed for individual projects.The
in noisy internal environments, it can be an
metres between clamped frames, in lengths
printed dots on clear ETFE sheet reduce the
inappropriate material if external noise is
up to between 15 - 30 metres, but lengths
light transmission to around 50-60%, but this
able to travel through the roof to internal
up to 60 metres have been used. Larger
can be increased further by printing dots on
spaces where a quiet environment is
cushions are made by welding sheet togeth-
two faces of the air-filled cushion in areas of
required. Cushions can also produce a
er in the workshop to form wider sheets to
the roof where more shading is required.
drumming effect during rain resulting from
form cushions that vary from the rectangular
MCR_ 179
Fabric 01 ETFE cushions 1
1 2
2 2 9
3
3
5 10
3
5
Section 1:5. Junction of clamping plates
Details
Detail E
Isometric view of junction of clamping plates
Section 1:5. Junction with adjacent roof
1. 2.
ETFE cushion Extruded aluminium clamping plate 3. Extruded aluminium retaining profile 4. Plastic edge bead to fabric membrane 5. Supporting structure 6. Plastic air supply tube 7. Main air supply tube 8. Insulated metal lined gutter 9. Metal flashing 10. ETFE cushion with contours shown for clarity
1
2
9 3
4
5
form created from a standard width of ETFE
aluminium, that holds the panel in place by
sheet. Cushions up to around 7.0 x 7.0
clipping it into an aluminium profile, then
supported by a structural frame beneath,
metres have been made in a variety of
holding it in place with an aluminium pres-
with mild steel, aluminium and laminated
shapes from circles to hexagons using a hot
sure plate that clamps the edges.The com-
timber all being used to suit the design. In
welded process undertaken in the workshop.
plete assembly usually performs in a similar
(E), the clamped framing assembly is fixed to
The welded seams are visible but are not
way to the framing used for glazed roofs,
mild steel tubes by fixing the framing onto T-
visually striking when viewed from around
with a drained and ventilated inner chamber
sections which are welded in short lengths
the building.The width, or span, of the cush-
that serves as a second line of defence
to the mild steel tube.The aluminium fram-
ion has an effect on its depth, where the
against rainwater penetration. Any rainwater
ing spans between the T-section supports to
depth is typically around 1/5 the span of the
that passes through the outer clamping plate
provide a visual separation between the
cushion. Larger cushions sometimes use a net
is drained away in grooves formed adjacent
ETFE cushions and the supporting steelwork.
of connected cables to provide additional
to the edges of the ETFE cushions, the water
restraint.
being drained back to the outside of the
The cushions have an edge bead, typically
roof.The clamping assembly is typically
The complete ETFE cushion assembly is
Durability The toughness of ETFE sheet is com-
in plastic, which is used to retain the panel in
around 100mm wide, which is wider than
bined with a high resistance to tear. Damage
its supporting frame.The cushion is set into a
that used for glazed roofs, but less framing is
by sharp objects puncturing an outer mem-
clamping frame, usually made from extruded
required than that used on glazed roofs .
brane does not spread easily into a larger
MCR_ 180
Isometric view of junction of ETFE cushion assembly
10
5
10
9 Arteplage, Neuchatel, Switzerland. Architect: Groupe Multipac.
2
3
8
5
Isometric view of junction of junction with gutter
tear easily. Birds can puncture the outer
ing along the external clamping plates with
burning fragments will fall below during a
membrane, but they have great difficulty in
cable assistance or from external structure.
fire, since the material melts rather than
coming to rest on the roof itself, except on
Roofs are designed so as to ensure rainwa-
burns, with most of the burnt material being
the clamping plates, where wire is some-
ter drains easily from the roof. Gutters are
carried away in the rising hot air of a fire.
times fitted to avoid providing any spaces for
introduced on long span roofs between sets
ETFE sheet melts at around 275°C, forming
birds to stand.The material has fairly high
of clamping plates, as shown in (F). Cushions
holes in the fabric which allows the heat and
resistance to surface fading from UV light
are repaired by the use of ETFE tape, which
smoke of a fire to escape. However, some
where there is a gradual loss of surface
is visible, or by complete replacement of the
roofs still require smoke vents, since this may
reflectivity. ETFE sheet is also highly resistant
panel, depending largely on the visual
not always occur during a fire if the smoke
to attack from chemicals and from airborne
requirements of the roof design.
and heat is being generated in an area away
pollution in urban areas. Its low level of surface friction ensures that cushions do not hold dirt and dust easily, making cushion
from the roof, where the ETFE cushions are
Performance in fire A major concern in the use of polymer
not affected by the fire.The small amounts of material used in ETFE cushions, with an aver-
roofs relatively easy to maintain. ETFE roofs
materials for single layer and multiple layer
age wall thickness of 0.2mm, result in little
are usually cleaned as a result of rain in tem-
fabric roofs is their performance in fire. ETFE
material being deposited during a fire.
perate climates, though access for mainte-
sheet is not easily inflammable and will self-
nance is required, usually provided by walk-
extinguish quickly under direct flame. Few
MCR_ 181
Fabric 02 Single membrane : Cone-shaped roof
1
11 1 1 1
2
2 Plaza de toros, Madrid, Spain. Architect: Schlaich Bergermann und Partner / Ayuntamiento de Madrid
Isometric view of cone-shaped fabric roof
Details
4.
1. 2. 3.
5.
Fabric membrane panel Supporting mild steel structure Extruded aluminium retaining profile
6.
Plastic edge bead to fabric membrane Extruded aluminium clamp assembly Stainless steel cable
7. 8. 9.
Stainless steel connector Membrane skirt Gutter formed by membrane skirt 10. Mild steel ring support 11. Fabric cover to close ring
Section 1:400. Cone-shaped fabric roof 11
1
1
2 2
2 2
The following two sections discuss the two
them.They use their curvature as a method
membrane without over-tensioning some
most common shapes used for single layer
of tensioning the membrane against a sup-
parts and under-tensioning other parts of
roofs: the 'cone-shaped' roof and the 'barrel-
porting structure, which is typically a mixture
the membrane, with the resulting design
shaped' roof. A third type, based on the
of mild steel tubes and stainless steel cables.
resisting all load combinations in their differ-
shape of a hyperbolic paraboloid, uses the same principles as those for these two types and is constructed using the same principles
ent directions.This work is usually developed
Fabric roof principles Early examples of fabric roof structures
in the form of a computer model, either by specialist structural consultants or by manu-
and same construction details. For that rea-
of 30 years ago were based, in part, on
facturers as part of the design development
son its specific geometry is not discussed
observations of how forces act in soap bub-
process.The minimal surface form must also
here, but the construction principles
bles, where the soap film wall of the bubble
be suitable for draining away rainwater,
described here can be applied equally to
takes up a minimum of surface area as a
which forms another aspect of design devel-
hyperbolic paraboloid forms.
result of the surface tension of the wall of
opment, together with the treatment of
The advantages of single membrane fab-
the bubble being evenly distributed. In a fab-
interfaces with adjacent areas roof and
ric roofs are their smooth curves, typically
ric roof the membrane is structurally mod-
external wall.The resulting form is designed
with different in opposite directions, and thin,
elled so that the resultant form developed
to keep all parts of the fabric membrane in
sharp edges that provide translucent roofs
between architect and structural engineer
tension, not just from the supporting struc-
that allow diffused daylight to pass through
distributes the tensile forces within the
ture but from imposed loads, mainly wind
MCR_ 182
Plan 1:400. Cone-shaped fabric roof
1
1
1
1
2
Elevation 1:400. Cone-shaped fabric roof
6
1
1 1
1
2 2
loads.Wind pressures are resisted by re-dis-
downloads from the membrane and
visual effect on the adjoining structure is bal-
tributing the forces within the fabric mem-
imposed loads (mainly wind loads) and the
anced with the requirements of the mem-
brane. Any areas of the fabric roof that go
lower points at the edges take up the effect
brane roof and its own frame.
into compression as a result of slackness in
of wind uplift. In shallow sloped roof mem-
the membrane reveal themselves as creases
branes, more of the structural loads are
sand can cause permanent stretching of the
in the material.
taken by the edges or points at the base,
fabric membrane, the form of the roof and
often resulting in large columns or posts
its associated slopes are made sufficiently
section and the barrel-shaped example of
being required at these points.The distribu-
steep to avoid creating areas or pockets on
the following section make use of an internal
tion of loads within the fabric roof design is
the fabric roof where they can collect.
steel structure that supports part of the
revealed in the supporting structure, which
membrane, to tension it in some areas, with
can be as visually lightweight and elegant as
roof edges where the material is held and
the fabric membrane itself, or can become
tensioned ,either at points or with continu-
visually heavy, which can detract from the
PVC-coated polyester fabric and PTFE-coat-
ous clamped fixings similar to those
intended lightweight effect of the mem-
ed glass fibre fabric. Both are woven cloth
described in the previous section on ETFE
brane.Where roofs transfer forces to an
materials which are protected by coatings,
cushions. Generally speaking, the high points
adjoining structure, rather than contain the
usually applied on both sides. Other open-
of the supporting structure take up the
loads within their own supporting frame, the
weave materials are used as solar shading
Both the cone-shaped example in this
Where imposed loads such as snow or
Fabric types The two most common fabrics used are
MCR_ 183
Fabric 02 Single membrane : Cone-shaped roof Section 1:50. Clamping ring with fabric cover
6
12
6 11
12
2
1
1
2
only, and are manufactured without protec-
Most fabric roof materials imitate the
PVC powder, softeners and plasticisers, UV
tive coatings.These are made from polymer
appearance of natural canvas, but this mater-
stabilisers, pigments and fire retardants. An
threads, sometimes with a protective coating
ial is used only where its appearance and
additional outer coat of lacquer slows down
applied to the manufactured thread itself, to
individual texture is considered to be the
the effect in the PVC coating of becoming
increase the life expectancy of the material. In
most important consideration. Natural can-
increasingly brittle with age, which results
all these woven materials the strength of the
vas is less stable than synthetic fabrics when
from the softeners within the material grad-
fabric can be different in the two directions
used in tension structures, and is difficult to
ually moving to the surface of the PVC coat-
in which the 'cloth' is woven.When selecting
clean. A modified acrylic canvas material,
ing.The lacquer coating also slows down the
a material, the strength of the' warp' threads
with a similar texture to natural canvas, is
fading effects of the colour pigments. A
running the length of the material is com-
sometimes used for its greater dimensional
PVDF lacquer (a fluorinated polymer) is typi-
pared to the 'weft' threads running the
stability. Neither material is suitable for long
cally used, which also ensures that the sur-
width. In most commonly used roof mem-
span fabric roofs.
face has low surface friction so that it will
branes, the tensile strength of the warp and
PVC/polyester fabrics are made from
attract little dust and dirt, and allowing the
weft directions are similar, but these need to
polyester cloth which is coated on both
membrane to be cleaned easily. Acrylic lac-
be checked when the material type is cho-
sides with a layer of PVC.The coating pro-
quers are also used.The typical weight of
sen.
tects the fabric against the effects of rain and
roof using this material is 500-800g/m². A
of UV light.The PVC coating is a mixture of
PVC/polyester membrane roof will last
MCR_ 184
Section 1:5. Base of roof with membrane skirt
Plan 1:10. Junction of adjacent fabric membranes
6 5
5 1
1 1
6
5
8 5
6
1
Details 1. 2. 3. 4. 5.
1
Fabric membrane panel Supporting mild steel structure Extruded aluminium retaining profile Plastic edge bead to fabric membrane Extruded aluminium clamp
1
assembly 6. Stainless steel cable 7. Stainless steel connector 8. Membrane skirt 9. Gutter formed by membrane skirt 10. Mild steel ring support 11. Fabric cover to close ring 5
Section 1:10. Clamping ring
5 8
1
5
8 5 5
around 15-25 years. PTFE/glass fibre membranes are made
Comparison of types Both PVC/polyester and PTFE/glass fibre
5
naturally from its manufactured beige colour after a few months of being exposed to sun-
from a glass fibre mat which is coated with a
have high tensile strength and high flexibility,
light.Weld marks that occur during fabrica-
PTFE layer such as Teflon. As with PVC/poly-
making them very suitable for curved and
tion also disappear as a result of bleaching in
ester membranes, the coating protects the
double curved roof membranes.They both
sunlight. PTFE/glass fibre has lower surface
fabric from the effects of both the weather
have a light transmission of 5-20% depend-
friction than PVC/polyester, allowing the for-
and UV light as well as forming a low friction
ing on the thickness of membrane used,
mer to remain cleaner, while PVC/polyester
surface to reduce the collection of dirt and
reflecting 75-80% of light. Neither will catch
requires cleaning more frequently. PTFE/glass
dust. Most dirt is washed away by rain, but
fire easily, and both resist the deteriorating
fibre requires greater care in transportation
some cleaning is needed using the same
effects of UV light, though PVC/polyester
to site and erection than PVC/polyester, the
methods as for PVC/polyester roofs.Typically
becomes increasingly brittle with age. Both
latter being capable of being folded without
it weighs 800-1500g/m².The life expectancy
have almost no acoustic performance and
damage to the membrane.
of a PTFE/glass fibre membrane roof is
have poor thermal insulation performance
longer than PVC/polyester membranes at
when used as a single membrane roof.
around 30-40 years.
PVC/polyester has a greater range of colours
Thermal insulation A single layer membrane fabric roof in
readily available, while PTFE/glass fibre is usu-
either PVC/polyester or PTFE/glass fibre typ-
ally white, the colour to which it bleaches
ically has a U-value of around 6.0W/m2K.
MCR_ 185
Fabric 02 Single membrane 1: Cone-shaped roof 6
2
Section 1:10. Base of fabric roof
Plaza de toros, Madrid, Spain. Architect: Schlaich Bergermann und Partner / Ayuntamiento de Madrid
Detail G
5
8
8
1
1 5
5
Section 1:10. Junction of adjacent fabric membranes meeting at same angle
Detail F
Section 1:10. Junction of adjacent fabric membranes meeting at different angles
Detail E 5
8
8
1
1
5
5 6
Where two layered membranes are used,
the use of double layer fabric membranes is
with a minimum air gap of 200mm between
set to develop considerably over the next
the membranes, the U-value can be reduced
10 years.
to around 3.0 W/m K. Double layer mema severely reduced light transmission, the
Durability Fabric roofs are highly susceptible to
2
branes are less commonly used as they have
within the building.
Acoustics Like ETFE cushions discussed in the pre-
damage from sharp objects. Small cuts in the membrane can be repaired with patches
translucency of the material being one of the
vious section, single layer membranes pro-
made from the same material which are
main advantages of the material.Thermal
vide no significant reduction of noise through
glued into position. Larger tears are repaired
insulation can be added to a double layer
the roof. A double layer roof with an
with hot air welders, usually undertaken by
membrane by using a translucent fibre-based
acoustic lining will provide some acoustic
the specialist contractor that installed the
insulation, as used in fibre glass cladding pan-
performance but will have the effect of los-
fabric roof. Large repairs are visible, and pan-
els discussed in the previous chapter.The
ing most of the light transmission through
els are replaced where visibility is the most
insulation can be fixed to the inner face of
the membranes. In addition, low frequency
important consideration. Since large tears
either membrane, depending on how the
sound is difficult to absorb due to the low
can affect the overall structural performance
roof void is ventilated.With the increasing
mass of the cladding material. In common
of the membrane, the complete membrane
importance of the role of thermal insulation
with ETFE cushion roofs, the roofs are
is sometimes removed for another panel to
in the reduction of energy use in buildings,
almost transparent to sound emitted from
be stitched or welded, and re-coated in the
MCR_ 186
Elevation 1:200. Membrane cover
Section 1:200. Cone-shaped fabric roof
Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.
11
1
1
1
Fabric membrane panel Supporting mild steel structure Extruded aluminium retaining profile Plastic edge bead to fabric membrane Extruded aluminium clamp assembly Stainless steel cable Stainless steel connector Membrane skirt Gutter formed by membrane skirt Mild steel ring support Fabric cover to close ring
1
2
2
2
factory. The outer surface of fabric roofs are cleaned with soft brushes that wash the
ceptible to mould growth than PTFE/glass
to drop down from the roof. PTFE/glass fibre
fibre fabrics, essentially because the latter has
fabrics fail at a around 1000°C, but seams
lower surface friction.
will fail at a much lower temperature of around 270°C.With both materials, the fail-
membrane surface, the work being done typically from either a mobile platform or by rope access cleaners (abseilers) who are
Performance in fire The performance of a membrane during
ure of the membrane forms holes in the roof which allow heat and smoke to escape.
attached in harnesses and suspended from
a fire depends on both the fabric used and
cables attached to a steel bracket anchor
the stitching at the seams, where this joining
point on the top of the membrane roof.The
method is used. Membranes lose their ten-
anchor point forms part of the steel or tim-
sion under high temperatures, with
on the underside of the membrane in an
ber supporting structure to the membrane
PVC/polyester stretching above 70-80°C,
internal space within the building, then either
roof. Cleaning is also an important consider-
and PVC/polyester seams starting to peel at
a second membrane is added or, more com-
ation in areas of high humidity where there
around 100°C. At 250°C the PVC melts,
monly, increased ventilation is provided with-
is a higher risk of mould forming on the sur-
leaving holes in the membrane. PVC has fire
in the space below the roof.
face of the fabric which can cause perma-
retardants in the coating so that it self-extin-
nent staining. Regular cleaning prevents
guishes when the flame source is removed
mould growth. PVC/polyester is more sus-
which results in few, if any, burning fragments
Condensation Where condensation is likely to occur
MCR_ 187
Fabric 03 Single membrane : Barrel-shaped roof
Plan, elevation 1:200. Barrel-shaped fabric roof 2
12
11
11
1
1
12 2
12
2
11
2
1
1
2
Membrane roof fabrication
being made increasingly by a cutting
rial folded over itself to strengthen the joint.
machine. Fabric panels are usually made
Joint widths vary from around 25mm to
ual panels of fabric which are cut from sheet
slightly undersized to allow for the stretching
100mm depending on the size of the mem-
material, the curved forms of membranes
of the material when it is under tension as a
brane and its associated loads. Additional
being formed from flat sheet material.The
roof membrane.
strips of fabric are usually bonded onto the
Roof membranes are made from individ-
conical-shaped example shown in the previ-
Fabric panels are joined together with
outer (upper) face of the stitched seam to
ous section is made from panels with edges
lapped seams which are either sewn, welded,
avoid rainwater penetration through the
that curve inward, while the barrel-shaped
bonded or joined in a combination of stitch-
sewn thread. PVC/polyester panels can be
roof shown in this section is made from pan-
ing and welding, with all processes being car-
stitched in conjunction with most lacquer
els with edges that curve outward. PVC coat-
ried out in the workshop.The width of the
types.
ed polyester fabric is made in widths from
lap, which is visible from below the roof as
2000-3000mm, in thicknesses up to 1.2mm,
well as from outside the building, is deter-
lap between panels, then heating the lapped
while PTFE coated glass fibre fabric is made
mined by the structural forces on the mem-
areas and pressing them together. Joint
in widths up to around 5000mm in thickness-
brane, with higher loads requiring wider
widths are similar to those required for
es up to 1.0mm. Large panels are usually cut
seams.
stitched seams. Seams in PTFE/glass fibre
Welded seams are made by forming a
by CNC cutting machines, with small pieces
In stitched panel joints, wider seams have
panels are formed by hot element welding
cut by hand, but even small pieces are now
more rows of stitching visible, with the mate-
rather than by stitching or bonding, with an
MCR_ 188
Section 1:10. Edge of roof 8
1
10
Isometric view of roof assembly
1
1
2
Section 1:10. Junction between panels
Details
Detail A
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.
8 1
1
10
Fabric membrane panel Supporting mild steel structure Extruded aluminium retaining profile Plastic edge bead to fabric membrane Extruded aluminium clamp assembly Stainless steel cable EPDM sealing tape Membrane skirt Gutter formed by membrane skirt Thermal insulation Welding seam Wind up lift cable (above membrane)
Isometric view of roof assembly
2 2 2 2
2
Japanese Pavilion Expo 2000, Hannover, Germany. Architect: Shigeru Ban.
additional fabric strip added either on top or
stronger joint. If the joint is first sewn then
brane with a series of stainless steel link
within the joint itself between the mem-
welded, this avoids the need for an addition-
plates. Straight edges are usually formed with
branes to provide the required strength. For
al strip to be added to the upper surface,
an edge bead made from a flexible PVC or
welded joints on PVC membranes, the edge
which can enhance the visual appearance of
EPDM rod in a small pocket.This reinforced
of the panel being jointed has the PVDF lac-
the membrane on its outer surface. Bonding
edge is then held captive within an alumini-
quer removed before welding, which is
with solvents is used on PVC/polyester fab-
um clamping plate assembly similar to that
applied again when the welding is complete
rics only, but can be done in conjunction
used for ETFE cushions, as (A) or alternative-
to ensure that the PVC is fully welded and
with most lacquers used on that material.
ly in a luff groove extrusion.
that the PVDF lacquer forms a continuous seal across the joint when formed.
Cable restrained curved edges to fabric
Membrane roof edges
roofs usually follow a circular or catenary
PVC/polyester can be both hot air welded
Edges of membranes are usually either
shape. A sleeve is formed by folding the
and hot element welded, the advantage of
gently curved or straight. Curved edges are
membrane back over itself and stitching or
hot air welding being that repair work and
formed with a cable held in a continuous
welding it to form a continuous pocket in
some complex jointing can be undertaken
pocket at the edges of the membrane. An
which a stainless steel cable is inserted. A
during erection on site. Fabric roofs with
alternative detail used in PTFE/glass fibre
25mm diameter stainless steel cable is typi-
high structural loads within the membranes
canopies is to have an exposed cable con-
cal, depending on the structural forces. A
can be both welded and sewn to provide a
nected to the clamped edges of the mem-
strip of membrane material or plastic is set
MCR_ 189
Fabric 03 Single membrane : Barrel-shaped roof Section 1:10. Edge of roof with penetration
Elevation 1:10. Roof penetration
Detail M 2
1
1 1 8
5
5
5
2
Details
2
1. 2. 3. 4.
9
Fabric membrane panel Supporting mild steel structure Extruded aluminium retaining profile Plastic edge bead to fabric membrane
10
2
Elevation 1:10. Roof penetration
2
2 2 5 1 8
2
between the cable and the membrane to
steel cable is required.The edges of the
membrane has reached a maximum size for
allow the two to move independently with-
membrane have a flexible plastic or EPDM
either fabrication or installation. In both cases
out abrasion occurring. A reinforced plastic
edge strip or rod, typically of 10mm diame-
the clamping plates are positioned to ensure
strip is sometimes added into the pocket but
ter, that prevents the membrane from slip-
that rainwater can run freely along its edge
this is not visible from either above or below
ping within the clamping assembly.The
rather than creating a barrier where rainwa-
the roof.
clamps sometimes have an additional cover
ter can collect.
Straight clamped edges use clamping
strip to serve as a first line of defence against
plates, around 100mm wide, set back to back
rainwater penetration but any rainwater that
corners or points, they are usually fixed to a
and bolted together, which comprise two flat,
passes into the groove, where the edge of
single mild steel plate.The cable is fixed into
grooved plates, rather than the clamping
the membrane is held captive, is drained
a stainless steel cable fixing which is secured
plate and supporting extrusion used at joints
away within the groove which also serves as
with a pin connection back to a supporting
between panels.The clamping plates are fixed
a drainage channel.Water is then drained at
steel plate.The corner of membrane is cut
back to either a visible cable which is set
the base of the roof.
to form a curved end. Additional straps are
Where two cables meet at membrane
around 100mm away from the edge of the
Clamping plates are also used at the
sometimes added to ensure that the mem-
cable, which follows the edge of the mem-
junction between two areas of roof where
brane does not slide away from the corner.
brane or, alternatively, individual brackets are
the two parts are required to be fabricated
fixed to a supporting wall, where no stainless
and installed separately, usually where the
MCR_ 190
Rainwater can be directed along the edge of a membrane, rather than being
Section 1:10. Edge of roof
Detail K
Section 1:10. Edge of roof at abutment
8
5. 6. 7. 8. 9. 10.
5 1
10 4
Extruded aluminium clamp assembly Stainless steel cable Stainless steel connector Membrane skirt Gutter formed by membrane skirt Thermal insulation
2
8 10
1 4
Section 1:10. Edge of roof 5 1
2
2
Section 1:10. Edge of roof
Detail L
Section 1:5. Edge of roof 1
1 5
5 4
2
8
8 2
Section 1:10. Clamping plate assembly
5
4
1 4
7
allowed to fall directly off the edge, by intro-
or, alternatively, by a 'palm tree' arrangement
the central mast or clamped around it.The
ducing a standing seam adjacent to the edge.
of projecting curved metal brackets which
ring is either freely suspended from cables,
A strip of membrane is rolled around a foam
serve to tension the continuous membrane
or is firmly fixed to the mast with can-
strip and is welded or stitched to the mem-
against its supporting mast set within the
tilevered brackets to which the ring is
brane.This is particularly useful where build-
building.
secured.
ing users pass beneath, as when the fabric
The first option with a metal ring
In the 'palm tree' supported solution,
roof forms an external canopy. Junctions
requires an additional membrane cover
cantilevered brackets with a curved shape
with vertically-set membranes beneath the
piece, while the second 'palm tree' option
are set out radially in order to create a
roof, are formed as flexible membrane con-
forms a continuous membrane with a
smooth curved form on which the mem-
nections to allow for movement between
smooth curved top, without any breaks in
brane is set.The brackets are usually aligned
roof and wall.
the continuity of the membrane. In the 'ring'
with joints between membrane panels.
solution, the membrane is clamped between
Suspension points Suspension points at the top of a cone-
an inner ring and an outer ring fixed together with bolts. A second clamp is used to fix
Membrane folds In an external fold in a roof membrane,
shaped fabric roof are usually formed either
the cone-shaped membrane that covers the
the material is draped over the supporting
by a metal ring, which is fixed back to a cen-
top of the ring.The top of the conical-
structure, fixed with fabric strips that are
tral mast by cables or cantilevered brackets
shaped cover is either pulled over the top of
sewn or welded to the underside of the
MCR_ 191
Fabric 03 Single membrane : Barrel-shaped roof
2
1
Section 1:10. Edge of roof with penetration 2
Section 1:200. Barrel-shaped fabric roof
1
Details 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
Fabric membrane panel Supporting mild steel structure Extruded aluminium retaining profile Plastic edge bead to fabric membrane Extruded aluminium clamp assembly Stainless steel cable Stainless steel connector Membrane skirt Gutter formed by membrane skirt Thermal insulation
5
8
2 2
Japanese Pavilion Expo 2000, Hannover, Germany. Architect: Shigeru Ban.
9
10
2 2
membrane and clamped to the supporting
each membrane is clamped with an edge
structure. An additional membrane cover
bead, while the clamp itself is fixed to a cen-
continuous line, as (F – previous section), the
strip is fixed to the top of the joint to con-
tral cable.The gap between the membranes
same principle of sewn or welded strips can
ceal the stitching if required. An alternative
is closed by two membrane strips which are
be applied, joined with a pressure plate set
method is to form a joint between two
sewn or welded to the base of the strip and
above the level of the adjacent roof, forming
membranes at the external fold, clamping
are clamped down to a thin pressure plate
two gutters where the pressure plate joint is
them with a pressure plate to an aluminium
between the membranes, as (E – previous
not submerged when functioning as a gutter.
extrusion which is supported by the primary
section).The clamp that closes the two
structure, such as a mild steel tube, curved to
membrane strips is supported off the metal
internal fold, a single membrane is sewn or
form the shape taken up by the membrane.
straps beneath. By raising the closing strips
welded to each side of the joint and the link-
Internal folds are formed in the same
above the height of the join, two adjacent
ing membrane is held in tension across the
way as hips, with the membrane folded out-
gutters are formed, with the clamping strip
junction. In practice this is difficult to fix
wards rather than across the ridge and
securing the closing flaps being above the
unless the strip is bonded or welded in posi-
downwards. In some cases the membrane
level of the water being drained, rather than
tion on site on at least one side of the mem-
may pass under the cable.These junctions are
being submerged in water if a single gutter
brane.The solution of two strips joined with
formed by clamping the ends of adjacent
were formed where the clamp holding the
a clamping plate allows more easily for fixing
membranes that form the valley.The edge of
straps in place were lower than that shown.
tolerances on site.
MCR_ 192
Where two joining members form a
Where a single gutter is required in an
Plan 1:10. Junction between membrane roof panels 11
3 5
5
5 11 5 2
9
9
5
5 10
2
At the base of a fabric roof, a clamping
roof, membrane skirts are used to form a
The membrane skirt at the base of the roof
plate fixed onto a base plate which is weld-
junction, as (A).The same principle is applied
is clamped to the side wall of an insulated
ed, or forms a continuous part of a support-
at the roof edge, as (K), where the mem-
gutter. Adjacent penetrations, also shown in
ing steel member, as (G – previous section),
brane continues over the edge of the roof
(M), are closed with a specially formed
provides a sealed termination to a roof. A
where it is mechanically fixed to a metal
membrane skirt that fits around the structur-
gutter to drain away rainwater or, alterna-
flashing. A clamping strip is used to fix the
al member that penetrates the roof.The top
tively, a metal sheet to shed water directly
membrane to the flashing, which also forms
of the skirt is clamped to the projecting
off the roof, can be added to the supporting
a watertight seal. In (L), the metal flashing is
structure, while the base of the skirt is site
structure.Where the clamping plate is at the
fixed to the timber arches.Thermal insulation
welded or bonded to the main roof mem-
base of a low pitched membrane roof,
is set between the metal flashing and the
brane panels.
where there is a risk of water being held
membrane to both avoid the member from
behind the clamping plate, an additional
becoming too hot from the effects of the
membrane skirt can be used to drain away
sun (as a result of direct contact with the
water.The membrane skirt is sewn or weld-
supporting steelwork) as well as to allow the
ed to the membrane in the workshop.
two components to avoid abrasion.The
Where the membrane is formed over arched supports, as in the barrel-shaped
same principle can be applied where a gutter is formed at the base of a roof, as (M).
MCR_ 193
PHOTO REFERENCES Cover photo: Hydrapier, Haarlemmermeer. Netherlands. Architect: Asymptote. Photographer: Christian Richters
13 Bolt fixed glazing 1 Hydrapier, Haarlemmermeer. Netherlands. Architect: Asymptote. Photographer: Christian Richters
21.Timber flat roof 2: Bitumenbased sheet Pavilion, Burgundy, France. Dirk van Postel. Photographer: Christian Richters
6. Metal standing seam Museum, Arnheim, Holland. Mecanoo architekten Photographer: Christian Richters
14. Bolt fixed glazing 2 Conference Bubble, Lingotto Factory Conversion,Turin, Italy. Renzo Piano Building Workshop Photographers: Gianni Berengo Gardin and Michel Denancé
22. Pitched roof:tiles Nara Centennial Hall, Japan. Arata Isozaki Photographer:Hisao Suzuki
7. Profiled metal sheet Atelier and House, Biwa-cho, Shiga Prefecture, Japan. Shuhei Endo Architect Institute Photographer:Yoshiharu Matsumura 8. Composite panels School of Decorative Arts, Limoges, France. Labfac / Finn Geipel, Nicholas Michelin Photographer: C. Demonfaucon
16. Glazed canopies Train Station, Heilbronn Auer und Weber / Schlaich Bergermann und Partner Photographer: Roland Halbe
9. Rainscreens Shimosuwa Municipal Museum, Lake Suwa, Japan. Toyo Ito & Associates Photographer: Courtesy of Toyo Ito & Associates
17. Concrete: Concealed membrane International Port Terminal, Yokohama, Japan. Foreign Office Architects Photographer: Satoru Mishima
10. Metal canopies The Giovanni and Marella Agnelli Art Gallery at Lingotto,Turin, Italy. Renzo Piano Building Workshop Photographer: Enrico Cano
18. Concrete: Exposed membrane Natural Unit / Studio House Masaki Endoh and Masahiro Ikeda Photographer: Hiro Sakaguchi
11. Greenhouse glazing and capped systems Auer und Weber Amazonian House, Stuttgart. Photographer: Roland Halbe 12. Silicone-sealed glazing and rooflights DG Bank, Berlin, Germany. Architect: Frank O Gehry Photographer: Roland Halbe MCR_ 194
15. Bonded glass rooflights+decks Pavilion, London. Toyo Ito & Associates Photographer: Courtesy of Toyo Ito & Associates
19. Concrete: Planted Saitama Prefectural University, Tokyo, Japan. Riken Yamamoto and Field Shop. Photographer: Courtesy of Office 20.Timber flat roof 1: Mastic asphalt Saltwater Pavilion, Neeltje Jans, Holland. Oosterhuis Associates. Photographer: Courtesy of Oosterhuis Associates
23. Pitched roof:slates Tateyama Museum of Toyama, Japan. Arata Isozaki & Associates. Photographer:Yasuhiro Ishimoto 24. Pitched roof: metal House, Wye River, Australia. Bellemo & Cat Photographer: Mark Munro 25. GRP rooflights Bus Station, Lugano, Switzerland. Mario Botta Photographer: Pino Musi 26. GRP panels and shells Bus Station, Hoofddorp,The Netherlands. NIO architecten Photographer: Hans Pattist 27. ETFE cushions Arteplage, Neuchatel, Switzerland. Groupe Multipac. Photographer: Roland Halbe 28. Single membrane: 1 Plaza de toros, Madrid, Spain. Schlaich Bergermann und Partner / Ayuntamiento de Madrid Photographer: Roland Halbe 29. Single membrane: 2 Japanese Pavilion Expo 2000, Hannover, Germany. Architect: Shigeru Ban Photographer: Roland Halbe
AUTHORSHIP Andrew Watts conceived the book, wrote the text, drew the illustrations on CAD and set out the pages. Andrew Watts has 20 years' experience working as an architect specialising in facade detailing on international projects with a wide range of construction technologies. He was a project architect for Jean Nouvel in Paris, working on some of his most notable buildings. Andrew Watts has a Masters Degree from the University of Cambridge in Interdisciplinary Design. More recently as a facade specialist, he has worked on some well-known projects around the world including Federation Square, Melbourne and the Millennium Bridge, London. He presented a paper on passive and low energy design to the PLEA Conference 2000. Andrew Watts is currently a facade specialist on the Bur Juman Project in Dubai, one of the largest facade projects in the Middle East. He is working on a companion volume in the Modern Construction series. Andrew can be contacted at
[email protected]. Yasmin Watts designed the book. She undertook both the illustrations and the graphic design of the layouts.Yasmin Watts was an architect at the Renzo Piano Building Workshop in Paris, where she worked on the Cultural Centre in New Caledonia, and the Cité Internationale in Lyon, France.Yasmin can be contacted at:
[email protected]. The German language edition of this book has been translated by Norma Kessler, who has adapted the book for use in the German speaking countries.
David Marold is Editor for Architecture and Building Techniques at Springer Verlag in Vienna. He has driven this book from a set of basic layouts to a completed book. He has a passion for books and their design, ranging from their wider content to the quality of print paper.
Satoru Mishima, Mark Munro, Pino Musi, Christian Richters, Hiro Sakaguchi, Hisao Suzuki.
AUTHOR'S THANKS
ADDITIONAL PHOTOGRAPHS USED IN THE INTRODUCTION
I would like to thank my mother, Mrs Helena Watts, for proof reading in the final stages. I would also like to thank the following people for providing photographic images: Asymptote Architects, Auer und Weber, Grant Suzuki of Shigeru Ban Architects, Bellemo & Cat, Paola Pellandini of Studio Architetto Mario Botta, Shuhei Endo, Masaki Endoh and Masahiro Ikeda, Frank O Gehry, Zaha Hadid Architects, Elizabeth Hughes of Foreign Office Architects, Groupe Multipac,Takako Fujimoto of Arata Isozaki & Associates, Mariko Nishimura of Toyo Ito & Associates, Labfac, Machteld Schoep of Mecanoo Architekten, Maurice Nio of NIO architecten, Oosterhuis Associates, Chiara Casazza of Renzo Piano Building Workshop, Dirk van Postel, Schlaich Bergermann und Partner,Tom Wiscombe of Emergent, Riken Yamamoto and Field Shop. I would like to thank all the following photographers for providing images of their work: Enrico Cano, C. Demonfaucon. Michel Denancé, Gianni Berengo Gardin, Roland Halbe, Peter Horn,Yasuhiro Ishimoto,Yoshiharu Matsumura,
1. Light Wing at MoMa Tom Wiscombe / Emergent Photographer: Courtesy of Emergent 2. Bruges Pavilion Toyo Ito & Associates Photographer: Roland Halbe 3.Tram Station, Strasbourg, France. Zaha Hadid Architects. Photographer: Roland Halbe 4. Natural Ellipse,Tokyo, Japan. Masaki Endoh and Masahiro Ikeda Photographer: Hiro Sakaguchi 5. Mercedes Benz Design Center, Stuttgart, Germany. Renzo Piano Building Workshop Photographer: Peter Horn Photographs of other projects in the Introduction which are illustrated elsewhere in the book have credits as per the photo references on the previous page. Photographs in the essay on roof testing are by the author.
MCR_ 195
This bibliography lists articles from the international technical press from the years 2000 to 2005.The subject matter of these articles covers general issues about the nature and the future of roof construction, from a materials-based standpoint. Magazine references are also given for further exploration of projects illustrated within the book. Arteplage, Neuchatel, Switzerland. Groupe Multipack. Casabella 705. November 2002. Blob and Build Architecture d'Aujourd'hui September/October 2002. Bolt fixed glazing: Conference Bubble, Lingotto Factory Conversion,Turin, Italy. Renzo Piano Building Workshop A+U December 1996. GA Document November 1996. Bolt fixed glazing: Hydrapier, Haarlemmermeer. Netherlands. Architect: Asymptote. Domus. October 2002. Breath of Fresh Air RIBA Journal February 2003. Bruges Pavilion Toyo Ito & Associates Architecture d'Aujourd'hui January/February 2002. Casabella 705 November 2002.
MCR_ 196
/ Ayuntamiento de Madrid Deutsche Bauzeitung. September 2000. Detail. January/February 2004. Composite panels School of Decorative Arts, Limoges, France. Labfac / Finn Geipel, Nicholas Michelin Architecture d'Aujourd'hui. April 2000. Techniques et Architecture. December 1994. Defining Component-based Design Architectural Record. July 2004. DG Bank, Berlin, Germany. Gehry Domus. August 2001. Architecture d'Aujourd'hui. July/August 2001. Emergent Architectural Forms A+U No.396. September 2003. Enginering Enlightenment Architectural Review July 2003. Form and Materials A+U No.412. May 2001. Glass Action Architectural Review August 2003.
Building with Metal Architectural Review June 2002.
Glass at the Cutting Edge Architectural Review August 2001
Canopy Plaza de toros, Madrid, Spain. Schlaich Bergermann und Partner
Greenhouse glazing and capped glazing Auer und Weber
Amazonian House, Stuttgart. Auer und Weber website GRP panels and shells Bus Station, Hoofddorp,The Netherlands. NIO architecten Architectural Review. December 2003. International Port Terminal, Yokohama, Japan. Foreign Office Architects Japan Architect. Autumn 2002. Domus. September 2002. Les Systèmes de Couverture Moniteur Architecture AMC May 2001. Light Wing at MoMa Tom Wiscombe/Emergent A+U September 2003. Manufacturing Complexity Architectural Design May/June 2004. Material Assets Architectural Review August 2004 Material Witnesses Architectural Review May 2000. Mercedes Benz Design Center, Stuttgart, Germany. Renzo Piano Building Workshop Architectural Review January 2000. Metal tiles House, Wye River, Australia. Bellemo & Cat Architectural Review. September 2003.
BIBLIOGRAPHY Natural Ellipse,Tokyo, Japan. Masaki Endoh and Masahiro Ikeda Architectural Review/April 2003 Architecture d'Aujourd'hui May/June 2003.
Rainscreens Shimosuwa Municipal Museum, Lake Suwa, Japan. Toyo Ito & Associates Japan Architect. Spring 1994.
Natural Unit / Studio House Masaki Endoh and Masahiro Ikeda JA Spring 2000 Architecture d'Aujourd'hui. January/February 2002.
Roof Construction. Detail 7/8. 2002.
Nature Talking with Nature Architectural Review January 2004.
Roofing Matters Architecture New Zealand July/August 2002.
On Shells and Blobs: Structural Surfaces in the Digital Age Harvard Design Magazine. Fall/Winter 2003-4. Pavilion, Burgundy, France. Dirk van Postel. Architectural Review. September 2002.
Roof Structures Detail 7/8. 2004.
Rooftop Oasis Architecture June 2001. Saitama Prefectural University, Tokyo, Japan. Riken Yamamoto and Field Shop. Japan Architect. Autumn 2003.
Renzo Piano Building Workshop A+U December 1996. GA Document November 1996. Sound and Light Made to Measure Architecture d'Aujourd'hui May/June 2003. Standing seam metal Museum, Arnheim, Holland. Mecanoo architekten Architectural Review August 2000. Casabella 687 March 2001. Tensile supported Japanese Pavilion Expo 2000, Hannover, Germany. Shigeru Ban Architectural Review. September 2000. The New Paradigm in Architecture Architectural Review February 2003.
Pavilion, London. Toyo Ito & Associates Casabella 711. May 2003. Japan Architect. Winter 2003.
Saltwater Pavilion, Neeltje Jans, Holland. Oosterhuis Associates. Architectural Review. December 1998.
Photovoltaic Cells RIBA Journal June 2002.
Skin Architecture A+U No.385. October 2002.
Polycarbonate rooflights Bus Station, Lugano, Switzerland. Mario Botta Architectural Review. April 2003.
Slate:Tateyama Museum of Toyama, Japan. Arata Isozaki & Associates. Domus. October 1996.
Profiled cladding Atelier and House, Biwa-cho, Shiga Prefecture, Japan. Shuhei Endo Architect Institute Architectural Review. August 2004.
Smart Skins for the Hyperbody Techniques et Architecture No.448. April/May2000.
Vegetation Systems Architectural Record. March 2003.
Solar shading The Giovanni and Marella Agnelli Art Gallery at Lingotto,Turin, Italy.
View from the Top Architecture Today. May 2001.
Tiles: Nara Centennial Hall, Japan. Arata Isozaki Japan Architect Yearbook 1999 Train Station canopy, Heilbronn. Auer und Weber / Schlaich Bergermann und Partner Industria delle Construzione. July/August 2001. Tram Station, Strasbourg, France. Zaha Hadid Architects. Casabella 702 July/August 2002.
MCR_ 197
A An overview of roof systems Metals Glass Concrete Timber Plastics Fabrics
8
8 10 12 13 14 14
B Bolt fixed glazing Generic support methods Supporting brackets Bolt fixings Arrangement of bolt fixings Glazed units Bolt fixed glazing: Pitched roofs and rooflights Base of glazed roof External and internal folds Small glazed rooflights Larger rooflights Bolt fixed glazing:Twin wall roofs. Bonded glass rooflights Generic conical rooflight Generic rectangular rooflight Generic monopitch rooflight Glass roof decks
78 79 79 80 81 82 84 85 86 87 88 90 96 96 97 99 99
C Composite panel roofs Single wall composite panels Twin wall panels Ridges Verges Eaves Parapets and valley gutters Concealed membrane Materials Structural joints Parapet upstands Balustrades and plinths Rainwater outlets Penetrations for pipes and ducts
46 46 48 49 49 50 50 110 110 111 113 114 114 115
E
MCR_ 198
ETFE Cushions
176
Cushions Air supply The material Fabrication Durability Performance in fire Exposed membrane Polymer-based membranes PVC membranes FPO (TPO) membranes Mechanically fixed method Bonded fixing method Parapets and upstands Ballasted roofs
176 177 178 179 180 181 116 117 118 119 119 119 120 121
F Flat roof. Mastic asphalt coverings Warm and cold roofs The material Warm roof build-up Solar protection Upstands Eaves and verges Penetrations Gutters and rainwater outlets Flat roof. Bitumen-based sheet membranes The material Roof build-up Solar protection Fixing methods Parapet upstands Junction with tiled roof Eaves and verges
130 130 130 131 133 133 134 135 135 136 136 137 138 138 139 140 141
G Glazed canopies Four edge restrained canopy Bonded glass canopies Greenhouse glazing and capped systems Greenhouse glazing Modern roof glazing Capped systems GRP Panels and shells Smaller panels and shells Larger panels and shells GRP Rooflights Eaves and upstands
102 105 106 66 66 69 69 168 168 171 162 164
Verges Abutments Sliding roof panels
166 166 167
M Metal canopies Bolt fixed panels Fixed metal louvre canopies Electrically operated louvres Metal rainscreen roofs Panel arrangement Parapets Monopitch ridges and verges Roof geometry Roof soffits Metal standing seam roofs Site-based method Prefabricated methods Sealed and ventilated roofs Roof openings Ridges and valleys Eaves and parapets
58 61 61 63 52 53 54 55 56 57 34 34 35 37 37 38 39
P Performance testing of roofs Air infiltration test Water penetration tests Wind resistance tests Impact resistance test Dismantling of sample Pitched roof: Metal Standing seam cold roofs Eaves and valley gutters Ridges and abutments Penetrations Metal tiled roofs Pitched roof: Slates Roof folds Vents Monopitch ridges Dormer windows Abutments Pitched roof:Tiles Plain tiles Interlocking tiles Ventilation Eaves Ridges Verges Hips and valleys
18 18 19 19 19 19 154 155 155 155 156 156 148 149 149 149 152 152 142 142 143 144 145 146 146 147
Abutments Planted concrete roofs Planted roof components Soil depth Overflows Roof junctions Rainwater outlets Balcony planters Profiled metal sheet roofs Profiled metal decks as substrates Profiled metal roof sheeting Sealed and ventilated methods Twin skin construction Ridges Openings Eaves and parapets Ridges and valleys
INDEX
147 122 123 124 125 125 126 126 40 40 41 41 42 43 43 44 45
R Roof-mounted facade cleaning systems 20 Davit systems 21 Monorails 23 Trolley systems 27 S Silicone-sealed glazing and rooflights Silicone-sealed systems Junctions Use of capped profiles Rooflights Single membrane: Barrel-shaped roof Membrane roof fabrication Membrane roof edges Suspension points Membrane folds Single membrane: Cone-shaped roof Fabric roof principles Fabric types Comparison of types Thermal insulation Acoustics Durability Performance in fire Condensation
72 72 73 75 76 188 188 189 191 191 182 182 183 185 185 186 186 187 187
W Working with manufacturers, fabricators and installers 16
MCR_ 199
Andrew Watts London, England
This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically those of translation, reprinting, re-use of illustrations, broadcasting, reproduction by photocopying machines or similar means, and storage in data banks. The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. © 2005 Springer-Verlag/Wien Printed in Austria SpringerWienNewYork is a part of Springer Science+Business Media springeronline.com Printing: Holzhausen Druck & Medien GmbH, 1140 Wien, Austria Printed on acid-free and chlorine-free bleached paper - TCF SPIN: 11367291 Library of Congress Control Number: 2005926671 With numerous (partly coloured) Figures
ISBN-10 ISBN-13
3-211-24071-3 SpringerWienNewYork 978-3-211-24071-7 SpringerWienNewYork
