Industry Guide
38 A Guide to Safe Scaffolding
N.C. Department of Labor Occupational Safety and Health Division 1101 Mail Service Center Raleigh, NC 27699-1101 Cherie Berry Commissioner of Labor
N.C. Department of Labor Occupational Safety and Health Program Cherie Berry Commissioner of Labor OSHA State Plan Designee Allen McNeely Deputy Commissioner for Safety and Health Kevin Beauregard Assistant Deputy Commissioner for Safety and Health Tom Savage Reviewer
Acknowledgments
A Guide to Safe Scaffolding was initially prepared for the N.C. Department of Labor by David L. Potts. Mr. Potts has written extensively about subjects regarding construction safety and is a recognized authority in safe scaffolding. The information in this guide was reviewed in 2008.
_____
The N.C. Department of Labor is grateful to the Scaffolding Industry Association for permission to use the illustrations in this guide.
_____
This guide is intended to be consistent with all existing OSHA standards; therefore, if an area is considered by the reader to be inconsistent with a standard, then the OSHA standard should be followed.
To obtain additional copies of this guide, or if you have questions about North Carolina occupational safety and health standards or rules, please contact: N.C. Department of Labor Education, Training and Technical Assistance Bureau 1101 Mail Service Center Raleigh, NC 27699-1101 Phone: (919) 807-2875 or 1-800-NC-LABOR (1-800-625-2267)
____________________ Additional sources of information are listed on the inside back cover of this guide.
____________________ The projected cost of the NCDOL OSH program for federal fiscal year 2009–2010 is $17,534,771. Federal funding provides approximately 30 percent ($5,180,700) of this total.
Reviewed 8/08
N.C. Department of Labor Occupational Safety and Health Program Cherie Berry Commissioner of Labor OSHA State Plan Designee Allen McNeely Deputy Commissioner for Safety and Health Kevin Beauregard Assistant Deputy Commissioner for Safety and Health Tom Savage Reviewer
Acknowledgments
A Guide to Safe Scaffolding was initially prepared for the N.C. Department of Labor by David L. Potts. Mr. Potts has written extensively about subjects regarding construction safety and is a recognized authority in safe scaffolding. The information in this guide was reviewed in 2008.
_____
The N.C. Department of Labor is grateful to the Scaffolding Industry Association for permission to use the illustrations in this guide.
_____
This guide is intended to be consistent with all existing OSHA standards; therefore, if an area is considered by the reader to be inconsistent with a standard, then the OSHA standard should be followed.
To obtain additional copies of this guide, or if you have questions about North Carolina occupational safety and health standards or rules, please contact: N.C. Department of Labor Education, Training and Technical Assistance Bureau 1101 Mail Service Center Raleigh, NC 27699-1101 Phone: (919) 807-2875 or 1-800-NC-LABOR (1-800-625-2267)
____________________ Additional sources of information are listed on the inside back cover of this guide.
____________________ The projected cost of the NCDOL OSH program for federal fiscal year 2009–2010 is $17,534,771. Federal funding provides approximately 30 percent ($5,180,700) of this total.
Reviewed 8/08
Contents P a rt
P age
Forewo Foreword rd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1i .1iii v 1
I nt n t r od od u ct ct io ion
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ivi 1
2
P ol ol i cy for S a fe fe S ca ca ff ffol d E r ec ect io i on a n d U se s e . . . . . . . . . . . . . . . . . . ii ii1 12
3
I ll llu s t r a t io ion s of S eell e ct ct e d Typ es es of S ccaa ff ffol d s . . . . . . . . . . . . . . . . . ii ii1 16
4
Ty p es es of S ca ca ff ffold in in g a n d I n fo for m a t io ion
. . . . . . . . . . . . . . . . . . . . ii ii22 22
G los s a r y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ii .ii30 30 R e fe r en e n ce ce s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ii .ii32 32
iii
Foreword Scaffolding can provide an efficient and safe means to perform work. However, unsafe scaffolding procedures can lead to accidents, serious injuries and death. This guide makes clear that planning ahead for the erection, use and dismantling of scaffolding can substantially reduce scaffold-related accidents and injuries. Compliance with the manufacturer’s instructions, the use of this guide and compliance with all scaffolding standards will help ensure a safer workplace for employees. Safety and health in the workplace is everyone’s responsibility. Employers must be aware of workplace hazards facing their workers, and they must take appropriate action to minimize or eliminate exposure to these hazards. Workers are responsible for following the policies, procedures and training requirements established by their employers. A Guide to Safe Scaffolding discusses precautions that can prevent serious accidents and protect workers against fall injuries and fatalities. N.C. Department of Labor inspectors enforce the federal Occupational Safety and Health Act through a state plan approved by the U.S. Department of Labor. The N.C. Department of Labor’s Occupational Safety and Health Division offers many educational programs to the public and produces publications, including this guide, to help inform people about their rights and responsibilities regarding occupational safety and health. OSHA puts great emphasis on efforts to help citizens find ways to create safe and healthy workplaces. Everyone profits from working together for safety. Reading and understanding A Guide to Safe Scaffolding will help you form sound occupational safety and health practices where you work. Cherie Berry Commissioner of Labor
v
1 Introduction Scaffolding has a va riety of applications. It is used in const ru ction, alter at ion, rout ine ma inten an ce an d ren ovat ion. Scaffolding offers a safer a nd m ore comfort able work ar ra ngemen t compa red t o lean ing over edges, stret ching overhead an d working from ladders. Suitable an d suf fi cient scaffolding mu st be supplied for work a t elevations th at cann ot be accomplished sa fely by other m ean s. Pr operly erected an d ma inta ined, scaffolding provides worker s sa fe access t o work locations, level an d st able working plat forms, a nd temporary st ora ge for tools and mat erials for performing immediate ta sks. Accidents involving scaffolding mainly involve people falling, incorrect operating procedures, environmen ta l condit ions a nd falling mat erials cau sed by equipment failur e. The causes of scaffolding accidents include failures at attachment points, parts failure, inadequate fall protection, improper construction or work rules, and changing environmental conditions (high winds, temperature extremes or the presence of toxic gases ). Addit iona lly, overloadin g of scaffolding is a frequ ent caus e of ma jor s caffold failur e. Individuals exposed to scaffolding ha zar ds include scaffold er ectors a nd disma nt lers, personn el work ing on scaffolds, and employees an d th e genera l public nea r s caffolding. Scaffold erectors a nd disman tlers are at particular risk, since they work on scaffolds before ladders, guardrails, platforms and planks are completely insta lled. This guide IS NOT INTE NDED t o be a guideline for compliance with a ll pertinent regulat ions en forced un der t he Occupa tiona l Safety and H ealth Act of North Car olina , but r at her an overview of safe pra ctices in scaffolding pr ocedur es. Though t he guide is not int ended t o be inconsistent with a dopted st an dar ds, if an ar ea is considered by th e rea der t o be inconsistent , the a pplicable sta nda rd sh ould be followed.
1
2 P o l i c y fo r S a f e S c a f fo l d E r e c t i o n a n d U s e Safe scaffold er ection a nd use should begin by developing policy and work ru les. Policy an d work r ules should concentr at e on: •
sound design
•
selecting the right scaffold for the job
•
assigning personnel
•
training
•
fall protect ion
•
guidelines for proper erection
•
guidelines for use
•
guidelines for altera tion and dismant ling
•
inspections
•
maintenance and storage
Sources of inform at ion for policy development an d work r ules include OSHA an d ANSI st an dar ds, scaffold tr ade a ssociations, scaffolding suppliers, a nd s afety an d engineer ing consu lta tion services.
Sound Design The scaffold should be capa ble of supporting its own weight a nd a t least four times t he m aximu m inten ded load t o be applied or t ra nsm itted t o th e scaffold and componen ts. Su spension ropes should be capa ble of supporting six times th e ma ximum intended load. Guar drails should be able to withst an d at least 200 poun ds of force on t he t op rail an d 100 poun ds on th e midra il. On complex systems, th e services of an engineer ma y be needed to determine th e loads a t pa rticular points.
S e l e ct i n g t h e R i g h t S c a ffo l d f or t h e J o b You can not cont ra ct awa y th e res ponsibility for se lecting th e righ t sca ffold for your job. But if you do cont ra ct for scaffolding: •
Choose a scaffold supplier, rent al a gency and/or er ector wh o is t horoughly knowledgeable about t he equipment needed and its sa fe use.
•
Obtain th e owner ’s ma nua l prepar ed by the scaffolding ma nufacturer, which st ates equipment limita tions, special warnings, inten ded use and m ainten ance requirements.
If you a re t o select your own scaffold, begin by reviewing the wr itten requ iremen ts (blueprint s, work orders, etc.) to deter mine wh ere scaffolds should be u sed a nd t he t ype of scaffolding needed. Make sur e tha t the scaffolds meet a ll government an d volunta ry r equirements. Consider t ha t scaffolds are generally ra ted light, medium a nd h eavy duty. Light du ty scaffolds can support a limited num ber of employees and ha nd t ools. Medium du ty scaffolds mu st be capa ble of safely holding work ers, h an d tools an d th e weight of const ru ction m at erials being insta lled. Heavy dut y scaffolds ar e needed when th e scaffold must sust ain work ers, tools and t he weight of stored ma ter ials. Account for an y special feat ur es of th e building str uctu re in relat ionsh ip to th e scaffold, including distinctive site condit ions. F actor t hese consider at ions into your policy: •
experience of erection a nd work ing personn el
•
length a nd kind of work t ask s to be perform ed 2
•
weight of loads to be sup ported
•
ha zar ds to people work ing on a nd n ear th e scaffolding
•
needed fall protection
•
mat erial hoists
•
rescue equipm ent (part icular ly for su spended s caffolds)
•
weather and environmenta l conditions
•
ava ilability of scaffolding, comp onent s, et c.
Assigning Personn el Assign a compet ent person t o oversee t he scaffold selection, erection, u se, movement, a ltera tion, dismantling, maintenance and inspection. Only assign trained and experienced personnel to work on scaffolding. Be cert ain th ey are k nowledgeable about t he t ype of scaffolding to be used a nd a bout th e proper selection, car e a nd use of fall protection equipmen t (perimeter protection, fall protection/work positioning belts an d full har nesses, lan yar ds, lifelines, rope grabs, sh ock absorbers, etc.).
Training Employees should receive instru ction on th e par ticular types of scaffolds th at they a re t o use. Train ing should focus on pr oper erection, ha ndling, use, insp ection, rem oval a nd car e of th e scaffolds. Tra ining must also include the insta llat ion of fall protection, pa rt icular ly gua rdr ails, and t he pr oper selection, use an d care of fall ar rest equipment. The compet ent person(s) should receive addit iona l tr ainin g regar ding t he s election of scaffolds, recognition of site conditions, scaffold ha zar d r ecognition, pr otection of exposed per sonnel a nd th e pu blic, repair an d replacement options, and r equirements of stan dards. Site ma na gement personn el should also be fam iliar with corr ect scaffolding procedur es so th ey can better determine needs a nd identify defi ciencies.
Fa l l P r o t e c t i o n Guar dra ils mu st be insta lled on all scaffold platforms in accorda nce with required sta ndar ds an d at least consist of top ra ils, midra ils and t oeboar ds (if more t ha n 10 feet above the groun d or fl oor). Th e t op edge height of topra ils or equ ivalent m ember on su pported scaffolds ma nu factu red or pla ced in ser vice after J an . 1, 2000, sha ll be insta lled between 38" and 45" above th e platform sur face. The top edge height on supported scaffolds ma nu factu red a nd pla ced in ser vice before J an . 1, 2000, an d on all suspended scaffolds where both a guardr ail and a per sona l fall arr est system a re r equired shall be between 36" and 45". When it is necessar y to remove gua rdr ails (for exa mple, to off-load m at erials), supervision m ust ensu re that they are replaced quickly. Ha rd h at s should be worn to protect a gainst falling objects. Mesh, screen s, int erm ediate vert ical mem bers or solid pa nels should be used to safeguar d employees an d th e public at lower levels. Ground-level safety can be furt her provided by erecting canopies; by prohibiting ent ry into th e fall ha zar d ar ea by policy, barr icades an d signs; and by th e proper placemen t of ma ter ials, tools an d equipmen t on scaffolding. Work ers on suspen ded scaffolds must use a fall arr est system as pr otection against th e failur e of th e scaffold or its component s. This system will usu ally consist of a full body ha rn ess, lanya rd, r ope gra b, independent vertical lifeline and an independent lifeline anchorage. The full body har ness is a belt syst em designed to distribut e th e impact en ergy of a fall over th e shoulders, th ighs and bu tt ocks. A properly designed h ar ness will perm it prolonged work er su spension after a fall with out rest ricting blood fl ow, which m ay cause in ter na l injuries. Rescue is a lso aided because of th e upr ight positioning of the worker.
3
A lanya rd conn ects t he sa fety ha rn ess to the rope grab on the lifeline. Mater ials should be ma de of 5 ⁄ 8" nylon r ope or n ylon webbing. Lanyar ds sh all be kept a s short as p ossible to limit fall distan ce or r igged such th at an employee can never free fall more t han six feet. Rope grabs cont ain a cam device th at locks ont o a lifeline when t her e is a ha rd t ug or pull on t he lan yard. Car e mu st be t aken to ensure tha t r ope grabs a re pr operly connected to lifelines so the cam will work corr ectly. Rope gra bs should be placed at th e highest point on th e lifeline to reduce th e fall dista nce an d unintent iona l disengagement. Indepen dent vertical lifelines (not scaffold su spension lines) of fi ber r ope should be used for ea ch person work ing on t he su spended scaffold. In t he pr esence of fl am e or hea t, wire r ope lifelines should be used with lan yar ds cont ainin g shock a bsorber s. Vert ical lifelines sh ould exten d from t he a nchorage point to th e groun d or a s afe lan ding place above the groun d. It is importa nt to remem ber th at fall protection is only as good as its a nchorage. The an chora ge points ar e independent points on st ructur es where lifelines a re securely atta ched. These points m ust be able to support at least 5,000 pounds per em ployee an d pr efera bly 5,400 poun ds for a fall of up t o six feet or 3,000 poun ds for a fall of two feet or less.
G e n er a l G u i d e l i n e s fo r P r o p e r E r e c t i on Accidents an d injur ies can be redu ced when th e guidelines in th is section ar e followed. Sup ervise th e erection of scaffolding. This mu st be done by a per son competen t by skill, exper ience an d tr aining to ensur e safe insta llat ion according to th e man ufacturer ’s speci fi cations a nd other r equirements. Know the volta ge of energized power lines. E nsu re increased awa ren ess of location of ener gized power lines; maint ain safe clear an ce between scaffolds a nd power lines (i.e., minimum dista nce of 3' for insula ted lines less th an 300 volts; 10' for in sula ted lines 300 volts or more). Identify heat sources like st eam pipes. Ant icipat e th e presen ce of hazar ds before er ecting scaffolds an d keep a safe dista nce from t hem . Be sure t ha t fall protection equipmen t is available before beginning erection a nd u se it as needed. Ha ve scaffolding mat erial delivered as close to th e erection sit e as possible to minimize th e need for m an ua l han dling. Arr an ge componen ts in t he order of erection. En sur e the a vailability of ma ter ial hoisting an d rigging equipmen t to lift component s to the erection point an d eliminat e th e need t o climb with component s. Exam ine all scaffold component s prior t o erection. Return and t ag “Do Not U se ” or destroy defective components. Pr ohibit or rest rict th e inter mixing of man ufactur ed scaffold component s, unless: (1) the component s together properly, without force, (2) the us e of dissimilar m eta ls will not redu ce stren gth, a nd (3) th e design load capacities are maintained.
fit
All scaffold decks sh ould be p lank ed a s fully as possible (beginning a t th e work su rface face) with gaps between pla nks n o more th an 1" wide (to account for pla nk wa rp a nd wa ne). (Figur e 1 shows types of planking.) The rem aining space on bear er m ember (between th e last plan k a nd gua rdr ail) cann ot exceed 1 2 " (the space required to install an additiona l plank). Guar dra il systems a re n ot r equired on t he build9 ⁄ ing side when t he plat form is less tha n 16" from t he bu ilding, except for su spended scaffolds wher e th e ma ximum d ista nce is 12". In a ddition, scaffold setba cks will depend upon t he n eeds of th e tr ade. As an example, ma sons requ ire t he scaffold plat form to be as close to the wa ll as possible (with in 6"), while lath ers an d plasterers using spraying appara tus m ust st an d back (an d prefer a setback distance of at least 18"). Platform units must not extend less tha n 6" over their support s un less they are cleated or conta in hooks or other r estra ining devices. When platform units ar e abut ted t ogether or overlapped to mak e a long platform, each end should rest on a sepa ra te su pport or equivalent su pport. Wood preser vatives, fi r e r e t a r d a n t fi nishes an d slip-resistant fi nishes can be a pplied to platform un its; however, no coat ing should obscure t he t op and bott om of wooden sur faces. If fi re reta rdan ts ar e used, an engineer should ensur e tha t t he plank (s) will car ry th e required load since fi re r etar dant s can reduce the plan k load capacity. Pr ovide suita ble access t o and between scaffolds (see fi gure 4). Access can be provided by portable ladders; hook-on ladder s; at ta chable ladders; stair way-type ladder s; integr al prefabr icat ed scaffold ru ngs; 4
direct passage from another scaffold, structure or personnel hoist; ramps; runways; or similar adequate mea ns. Crossbra ces and scaffold fra mes sh all not be used for access scaffold platform s un less th ey are equipped with a bu ilt-in ladder sp eci fi cally designed for su ch pur pose. All ladders in use m ust meet OSHA speci fi cations, designed according to standards and secured against displacement. The bottom steps of ladder s mu st n ot be more th an two feet from the su pporting level. Rest plat form s ar e recommended for a t least every 30 – 36' of elevat ion. Wh en direct a ccess is u sed, spa cing bet ween scaffold a nd an oth er su rface should be no more t ha n 14" horizont ally and 2 feet vert ically. Additiona l r ecommenda tions for th e er ection of support ed scaffolds, sus pension scaffolds, fabricat ed frame scaffolds, outrigger scaffolds, etc., are also described in this booklet.
G u i d e l i n e s fo r U s e •
Be certa in th at scaffolds and components a re n ot loaded beyond t heir r ated an d ma ximum capa cities.
•
Pr ohibit t he m ovemen t of scaffolds when employees ar e on th em.
•
Maint ain a safe distan ce from ener gized power lines.
•
Pr ohibit work on scaffolds un til snow, ice an d other m at erials t ha t could cause slipping an d falls ar e removed.
•
Pr otect su spension r opes from cont act with sources of heat (welding, cut ting, etc.) an d from acids and other corrosive substances.
•
Pr ohibit scaffold use dur ing storms a nd h igh winds.
•
Remove debris an d un necessar y mat erials from scaffold platform s.
•
Pr ohibit th e use of ladder s an d oth er devices to increa se work ing heights on platform s.
G u i d e l i n es fo r A l t er a t i o n a n d D i s m a n t l i n g •
Require th at scaffolds be altered, moved an d disman tled un der t he su pervision of a competen t per son.
•
Alterat ion and dismant ling activities should be plan ned a nd performed with the same car e as with erection.
•
Tag any incomplete scaffold or damaged component out of service.
Inspections Insp ect a ll scaffolds and componen ts u pon receipt a t t he erection location. Retur n, ta g “Do Not U se ” or destr oy defective componen ts. Ins pect scaffolds before use an d at ta ch a ta g stat ing the t ime an d dat e of inspection. Inspect scaffolds before each workshift and especially after changing weather conditions and prolonged int err upt ions of work . Check for such item s as solid founda tions, sta ble conditions, complet e working and rest platforms, suitable anchorage points, required guardrails, loose connections, tie-off points, da ma ged components, pr oper access, an d t he use of fall protection equipment.
Ma i n t e n a n c e a n d S t o r a g e Mainta in scaffolds in good r epair. Only replacement components from th e original m an ufacturer should be used. I nt ermixing scaffold components from different ma nu factu rer s sh ould be avoided. Fa bricat ed scaffolds should be repaired according t o the m an ufacturer ’s speci fi cations a nd gu idan ce. J ob-built scaffolds should not be repair ed without t he su pervision of a competen t per son. Store all scaffolding par ts in an organized man ner in a dry an d protected environmen t. Exam ine all par ts a nd clean, repa ir or dispose of th em as n ecessar y.
5
3 Il lu s t r a t i o n s o f S e l e c t e d Ty p e s o f S c a f fo l d s Illustr at ions in t his pa rt offer t he r eader a gener al pictorial repr esent at ion of selected t ypes of scaffolds which a re a ddressed by standa rds en forced under the Occupat iona l Safety an d Hea lth Act of North Carolina (OSHANC standa rds). The reader must not rely upon t he illustr ations to determine safety requirement s or sa fe use of the equipment for a ny par ticular installation situa tion. Rath er, the reader should refer t o the appropriate OSHANC stan dar d an d related t ables for specifi c inform at ion. Th e illustr ations reference the OSH ANC sta nda rds (29 CFR 1926 applies to the constr uction indu stry a nd 29 CFR 1910 applies to gener al indu str y). Illustr at ions in th is part were provided by the Scaffolding Indu str y Association. The illustr at ions a re not int ended by th e N.C. Depar tm ent of Labor or the S caffolding Indust ry Associat ion t o endorse an y speci fi c product, design or insta llation. Figure 1 Sca ffoldin g Work S ur faces [29 CFR 1926.451(a ); 29 CFR 1910.28(a )]
LAMINATED VENEER LUMBER (LVL)
SOLID SAWN LUMBER SCAFFOLD PLANKS
FABRICATED SCAFFOLD PLANK FABRICATED SCAFFOLD DECK
STAGE PLATFORM
DECORATOR PLANK
WOOD SCAFFOLD PLANK
METAL SCAFFOLD PLANK
MODULAR STAGE PLATFORM
6
Figure 2 Wood P ole Sc a ffold [29 CFR 1926.452(a); 29 CFR 1910.28(b)] POLE
PLANKED LEVELS GUARDRAIL SYSTEM
ACCESS LADDER
BEARER
DIAGONAL BRACING RUNNER
Figure 3 Tub e an d Cou pl er Sca ffold [29 CFR 1926.452(b); 29 CFR 1910.28(c)] PLANKING GUARDRAIL SYSTEM WITH TOEBOARDS
RUNNER BEARER POST
RIGID CLAMP
SILL DIAGONAL BRACE CROSSBRACING BASE PLATE SWIVEL CLAMP
7
TYPICAL JOINT CONNECTION
Figure 4 F a b r i c a t e d F r a m e S c a f fo l d ( T u b u l a r W e l d e d F r a m e S c a f fo l d ) [ 2 9 C FR 1 9 2 6 .4 5 2( c ) ; 2 9 C FR 1 9 1 0 .2 8 (d ) ] a n d S c a f fo l d A c c e s s ( L a d d e r o r E q u i v a l e n t ) [ 2 9 C F R 1 9 2 6 .4 5 1 (e ) ; 2 9 C F R 1 9 1 0 .2 8 ( a ) ( 12 ) ]
HANDRAIL SYSTEM
GUARDRAIL CROSSBRACE
FRAME or PANEL STEP UNIT
INTERNAL STAIR UNIT
ACCESS GATE INTERMEDIATE LEVEL
TOEBOARDS
FRAME or PANEL ACCESS LADDER
BRACKET ATTACHMENT COUPLER
EXTERNAL LADDERS ATTACHABLE
BUILT-IN
8
Figure 5 M a n u a l l y P r o p e l l e d M o b i l e S c a f fo l d ( F a b r i c a t e d T u b u l a r F r a m e ) [ 2 9 C FR 1 9 2 6 .4 5 2 (w ) ; 2 9 C FR 1 9 1 0 .2 9 ] WORK PLATFORM
ACCESS GATE
GUARDRAIL SYSTEM
END FRAME TOEBOARD
LOCKING PINS
COUPLER
ACCESS LADDER
CROSSBRACING
HORIZONTAL DIAGONAL BRACE
LOCKING CASTERS CASTER FASTENING PINS
9
Figure 6 E x a m p l e s o f V e h i c l e -M o u n t e d E l e v a t i n g a n d R o t a t i n g A e r i a l D e v i c e s (c o v e r e d b y A N S I A 92 .2 ) [29 CFR 1926.453]
VEHICLE-MOUNTED AERIAL PLATFORM WITH TELESCOPING AND ROTATING BOOM
VEHICLE-MOUNTED AERIAL PLATFORM (SCISSOR TYPE)
10
Figure 7 Ou tr igger Sca ffold [29 CFR 1926.452(i); 29 CFR 1910.28(e)]
THIS END RIGIDLY SECURED
OUTRIGGER BEAM BLOCKED FOR LATERAL SUPPORT
11
Figure 8 Mason’s Adjustable Multiple-point Suspension Scaffold (With Winding Drum Hoists) [29 CFR 1926.452(q); 29 CFR 1910.28(f)]
ALTERNATE BOLT & SPECIAL ANCHOR IMBEDDED IN CONCRETE AT TIME OF POUR ANCHORAGE SYSTEM
TYPICAL SUPPORT FOR STRUCTURAL STEEL
OVERHEAD PROTECTION
GUARDRAIL SYSTEM WITH SCREEN
12
BUILDING STEEL
Figure 9 ( S w i n g i n g S c a f f o l d ) T w o -p o i n t S u s p e n s i o n [ 2 9 C F R 1 9 2 6 .4 5 2 (p ) ; 2 9 C F R 1 9 1 0. 2 8( g ) ]
COUNTERWEIGHTS
TIEBACK COUNTERWEIGHTS
TIEBACK OUTRIGGER BEAM ROLLING OUTRIGGER BEAM SUSPENSION WIRE ROPES
TIEBACKS
PARAPET CLAMP
SECOND WIRE ROPE WOOD BLOCKING
ROOF HOOK
SUSPENSION WIRE ROPES
SUSPENSION WIRE ROPE
POWERED TRACTION HOIST PLATFORM GUARDRAIL SYSTEM WITH SCREEN & TOEBOARDS GUARDRAIL SYSTEM WITH TOEBOARDS
SUSPENSION WIRE ROPE POWER WINDING DRUM HOIST
MODULAR PLATFORM
GUARDRAIL SYSTEM WITH TOEBOARDS
MANUAL WINDING DRUM HOIST PLATFORM
13
Figure 10 M u l t i p l e -p o i n t S u s p e n s i o n S c a f f o l d [ 2 9 C FR 1 9 2 6. 4 52 ( q ) ] INDEPENDENT LINE
HOIST LINE
GUARDRAIL SYSTEM
STAGE
HOIST
14
Figure 11 M u l t i -l e v e l S u s p e n s i o n S c a f fo l d W i t h P o w e r e d H o i s t s [ 2 9 C FR 1 9 2 6 .4 5 2 (v ) ]
SECOND WIRE ROPE LANYARD ATTACHED TO TROLLY LINE SUSPENSION WIRE ROPE
HOISTING MACHINE
PLATFORM UNITS
GUARDRAIL SYSTEM GUARDRAIL SYSTEM
15
Figure 12 S t o n e S e t t e r s ’ A d j u s t a b l e M u l t i p l e -p o i n t S u s p e n s i o n S c a f fo l d ( Wi t h M a n u a l W i n d i n g D r u m H o i s t s ) [ 2 9 C FR 1 9 26 . 45 2 ( q ) ; 2 9 C F R 1 9 1 0 .2 8 ( h ) ]
HOIST LINE
OUTSIDE WIRE ROPE
TOPRAIL
GUARDRAIL BRACKETS
INSIDE WIRE ROPE OPERATING HANDLE
MIDRAIL TOEBOARD ROLLER BUNTER GUIDE CLAMP
PLATFORM
PUTLOG PUTLOG HINGE BOLT
END GUARDRAIL SYSTEM
TOPRAIL
INTERMEDIATE GUARDRAIL SUPPORT
CORNER BRACE BOLT WIRE ROPE GUIDE WHEEL
END BRACKET GUARDRAIL SUPPORT
END GUARDRAIL SYSTEM
MIDRAIL TOEBOARD
PLATFORM SIDERAIL
Figure 13 S i n g l e -p o i n t A d j u s t a b l e S u s p e n s i o n S c a f fo l d s ( W or k C a g e s ) [29 CFR 1926.452(o); 29 CFR 1910.28(i)]
POWER TRACTION HOIST WORK CAGE
POWER TRACTION HOIST WORK CAGE WITH EXTENSIONS 16
SINGLE POINT SUSPENSION SCAFFOLD WINDING DRUM HOIST
Figure 14 S i n g l e -p o i n t A d j u s t a b l e S u s p e n s i o n S c a f fo l d B o a t s w a i n ’s C h a i r s [29 CFR 1926.452(o); 29 CFR 1910.28(j)]
BOATSWAIN CHAIR MANUAL
BOATSWAIN CHAIR POWERED
Figure 15 F o r m S c a f f o l d C a r p e n t e r ’s B r a c k e t S c a f f o l d ( Me t a l ) [29 CFR 1926.452(g ); 29 CFR 1910.28(k )] WALL STUD
GUARDRAIL POST LOCATION
THRU BOLT
17
Figure 16
Figure 17
B r i c k l a y e r ’s S q u a r e S c a f f o l d [29 CFR 1926.452(e)]
Horse Scaffold [29 CFR 1926.452(f); 29 CFR 191 0.28(m)]
BEARERS LIGHT DUTY 8' MAX MEDIUM DUTY 5' MAX
LEGS
CORNER BRACES
Figure 18 N e e d l e B e a m S c a f fo l d ( S t r u c t u r a l M e m b e r A b o v e ) [ 2 9 C F R 1 9 2 6. 4 52 ( u ) ; 2 9 C F R 1 9 1 0 .2 8 (n ) ]
ROPES
NEEDLE BEAM
PLATFORM
18
Figure 19 Inter ior Hu ng Sca ffold [29 CFR 1926.452(t); 29 CFR 1910.28(p)]
BUILDING STRUCTURAL MEMBER
SUPPORTING ROPE (ALTERNATE TUBE & COUPLER)
PLANK
BEARER
Figure 20 Ca ten a ry Sc a ffold [29 CFR 1910.28(g); 29 CFR 1926.452(r)] STRUCTURE ABOVE
PLATFORM
VERTICAL PICKUPS
ANCHORED
ANCHORED
WIRE ROPE HOOK STOPS
19
Figure 21 Ladder Jack Scaffold [29 CFR 1926.452(k); 29 CFR 1910.28(q)]
PLANK HEAVY-DUTY LADDER
OVERHANG
LENGTH OF FABRICATED PLANK VARIES
LADDER JACK (SECURE PLANK TO BOTH LADDER JACKS) HEIGHT
SECURE TOP AND BOTTOM OF BOTH LADDERS
UPPERMOST USABLE RUNG—SECOND HIGHEST
JACK INSTALLED ON SIDE OF LADDE R AWAY FROM SURFACE
JACK INSTALLED ON SIDE OF LADDER TOWARD SURFACE
Figure 22 Wind ow J a ck S ca ffold [29 CFR 1926.452(l); 29 CFR 1910.28(r)]
BUILDING STRUCTURE
ANCHOR
WINDOW OPENING
20
Figure 23 Float or S hip Sca ffold [29 CFR 1926.452(s); 29 CFR 1910.28(u)] STRUCTURAL MEMBER
SUPPORT ROPE DECK WITH BRACING EDGE PROTECTION
Figure 24 P u m p J a c k S c a f fo l d [ 2 9 C FR 1 9 2 6 .4 5 2 (j ) ] STRUCTURE
POLE
WORKBENCH (GUARDRAIL)
POLE
BRACE
MIDRAIL
END GUARDRAIL SYSTEM TOEBOARD
WORK PLATFORM
PUMP JACK BRACKET
BRACE MUD SILLS
21
4 Ty p e s o f S c a f fo l d s a n d I n f o rm a t i o n R e g a r d i n g T h e i r U s e Ther e ar e ma ny differen t t ypes of scaffolds, each with un ique feat ur es. Becau se of this distinctiveness, procedur es for sa fe erection an d use m aybe un ique to th e par ticular scaffold. Guidelines for sever al scaffolds ar e offered in th is par t. They a re gr ouped u nder th ree cat egories: self-support ing scaffolds, suspension scaffolds a nd special us e scaffolds.
S e l f-S u p p o r t i n g S c a ffo l d s A self-support ing scaffold is one or m ore work platforms su pported from below by out riggers, bra ckets, poles, legs, uprights , posts, fram es or similar support s. General Requirements
Con fi rm tha t scaffold and assembly are capable of support ing their own weight a nd a t least four times the maximum intended load a pplied or t ra nsmitted to the scaffold and components. Ensu re t hat poles, legs, posts, fra mes an d upr ights bear on base plates a nd m ud sills or other adequat ely fi rm founda tions. Footings mu st be level, soun d an d able to support t he loaded scaffold without set tlemen t or displacement . Plum b or br ace poles, legs, posts, fram es an d upr ights to prevent swa ying or displacement . Any support ed scaffold with a height of more th an four times t he min imum widt h of th e base mu st be restrained from tipping by guying, tying, bracing or other suitable means. Restraints are needed for every 26' (vert ically), with th e top restr aint as close to the t op plat form as possible (but not furt her from t he t op tha n four times th e least base dimension). Fabricated Frame
A fabr icat ed fra me scaffold (tubu lar welded fram e scaffold) is a support ed scaffold consistin g of a plat form(s) support ed on fabricated end fram es with int egral posts, horizonta l bearers an d inter mediate members (see fi gure 4). Fr am es an d pan els must be supported by cross, horizont al or diagona l braces, or a mixtur e of bra ces, to sta bilize vertical members. Cr ossbra ces should be long enough t o squa re a nd align vertical mem bers, to produce an er ect scaffold tha t is plum b, level and squ ar e. Brace conn ections m ust be secur ely fast ened. Fr am es an d pan els must be conn ected vert ically by coupling, stacking pins, or equal mea ns. Bra ckets support ing can tilevered loads mu st be seated with side-bra ckets pa ra llel to th e fra mes an d end-bra ckets a t 90 degrees to the fram es. If loads a re t o be placed on a platform extension, th e scaffold must be restr ained from tipping and putlogs or knee brace extensions must be used. (Excessive loads on side brackets could cause a frame leg failure.) Existing platform s mu st be left in place until new end fra mes h ave been placed an d bra ced, prior t o moving the pla tforms t o th e next level. Scaffolds over 125' high mu st be des igned by a registered pr ofessiona l engineer an d be const ru cted a nd loaded consisten t with th e design. Tu b e a n d C o u p l e r
A tube a nd coupler scaffold is a support ed scaffold consist ing of plat form s su pported by individua l pieces of tu bing, erected with coupling devices conn ecting u pright s, bra ces, bearer s an d r un ner s (see fi gur e 3). A register ed professiona l engineer ma y need to be consulted a bout th e design, const ru ction, an d loading of the scaffold. Tube and coupler scaffolds over 125' high must be designed by a registered professional engineer and be constructed and loaded consistent with the design. Tra nsverse br acing form ing an “X” across th e width of the scaffold mu st be inst alled at th e scaffold ends a nd a t least at every third set of posts horizont ally (mea sur ed from only one end) an d every fourt h ru nner vertically. Bracing must extend diagona lly from th e inner or outer posts or r unn ers u pward to the next outer or inner posts or ru nner s. Building ties mu st be insta lled at the bear er levels between th e tr an sverse bra cing an d mu st conform to the r equirem ent s of 1926.451(c)(1). This bra cing mu st be placed for ea ch section of six levels between t he four th an d sixth levels. The br acing must extend dia gona lly from the inn er or outer posts or r unn ers a t t he bottom of the four th level, upwar d to the inn er or outer 22
posts or run ners a t th e bottom of the fi fth level, an d likewise to th e sixth level. If this t echn ique is used, th e scaffold should be tied at t he “k ” funct ion level. On str aight r un scaffolds, longitu dina l bracing across the inn er a nd outer rows of posts must be insta lled diagona lly in both directions a nd m ust extend from the ba se of th e end posts upwar d to the top of th e scaffold at a pproximately a 45 degree an gle. When t he length of th e scaffold is grea ter th an th e height, such bra cing must be repeated st ar ting at least with every fi fth post. When t he length is sh orter tha n t he h eight, su ch br acing mu st be insta lled from t he base of end posts upwar d to th e opposite end posts an d th en in alt ern at ing directions un til the top of th e scaffold is rea ched. In situa tions wher e the a tta chmen t of bracing to posts is precluded, the bra cing must be att ached to the r unn ers. Bearers m ust be insta lled tra nsversely between t he posts, and when coupled to the posts, the inboard coupler mu st bear directly on t he r unn er coupler. When the bear ers a re coupled to the ru nner s, the couplers m ust be as close to the posts as possible. Bear ers m ust extend beyond t he posts an d ru nn ers a nd pr ovide full cont act with t he coupler. The scaffold must ha ve runn ers insta lled along its length a long both the inside and outside posts a t t he various level heights. Run ners must be interlocked on stra ight ru ns t o creat e continu ous lengths a nd be coupled to each post. Bott om ru nn ers sh ould be located a s close to th e base a s possible. Coupler s mu st be ma de of str uctur al met al. When plat form s ar e being moved to the next level, th e existing plat form m ust be left u ndistur bed unt il new bear ers h ave been set in place an d bra ced prior t o receiving the n ew platforms. Mobile
A mobile scaffold is a powered or n onpowered, porta ble, cast er or wheel-mount ed su pported scaffold (see fi gure 5). Mobile scaffolds const ru cted of tu be an d coupler component s or of fabr icat ed fra mes m ust conform to design, const ru ction an d loading requ iremen ts for th ose scaffolds. The scaffolds mu st be bra ced by cross, horizont al or dia gona l bra ces, or combina tion th ereof, to prevent ra cking or collapse; vertical members m ust be secured t ogether later ally so th at vertical members a re squa red a nd a ligned. Cross, horizont al or diagona l braces, or a combina tion, must be used to prevent collapse an d secure vert ical members later ally so tha t vertical members a re squar ed and a ligned. Scaffolds mu st be plum b, level and squ ar ed. All bra ce conn ections m ust be secur ed. Plat form s should not extend past the base supports u nless outr igger frames or equivalent devices ar e used t o ensure st ability. A rolling scaffold load capa city is a lso limited by t he weight its cast ers can su pport. P latforms sh ould not extend pa st t he bas e support s un less out rigger fram es ar e used. A rolling scaffold load capa city is also limited by the weight its casters can support. Cast er a nd wheel stem s mu st be pinned or otherwise secured in scaffold legs. While in a st at iona ry position, cast ers a nd wheels mu st be locked with a positive wheel an d/or wheel an d swivel locks, or equivalent m eans, to prevent movement. Employees should not be allowed to ride on a mobile scaffold unless strict controls are followed (level an d un obstr ucted su rfaces, a height r at io to width of not m ore tha n t wo to one, slow speed of movement , con fi nem ent of employees within th e scaffold fram e, etc.) When ma nu al force is used to move the scaffold, th e force should be applied as close to the ba se as pr acticable, but not more th an 5' above the su pporting sur face (i.e., scaffold base or wh eels when a powered syst em is u sed). Powered syst ems u sed to pr opel mobile scaffolds mu st be designed for such u se. Forklifts, t ru cks, similar motor vehicles or a dd-on motors should n ot be u sed t o propel scaffolds un less th e scaffold is designed for such p ropulsion systems. P o l e S c a f f o ld
A single pole scaffold is a support ed scaffold consistin g of plat form s r esting on bear ers, t he out side ends of which ar e support ed on ru nn ers (ledgers or r ibbons) secured t o a single row of posts or u pright s, an d th e inner ends of which ar e support ed on or in a str uctur e or bu ilding wall. A double pole (independent pole) scaffold is a support ed scaffold consist ing of platforms r esting on cross beam s su pported by ledgers an d a double row of uprights independen t of support (except for t ies, guys a nd br aces) from a ny structure.
23
On double pole scaffolds, crossbra cing m ust be insta lled between t he inn er a nd out er s ets of poles (see fi gure 2). Diagonal bra cing in both dir ections m ust be insta lled across th e ent ire outside face of doublepole scaffolds u sed t o support loads equ ivalent t o a un iformly distribut ed load of 50 poun ds or m ore per squa re foot. On both double an d single pole scaffolds, diagona l bra cing mu st be inst alled across th e ent ire outside face. Runn ers a nd bea rer s sha ll be insta lled on t he edges (e.g., na rr ow side on a 2" x 4", th e edge would be the 2" side). Bearers must extend a maximum of 3" over the outside edges of run ners. Run ners must extend over a m inimum of two poles an d be support ed by bearing blocks secur ely att ached t o the poles. Bra ces, bear ers a nd r un ner s cann ot be spliced between poles. Where wooden poles are spliced, the en ds must be squared a nd t he upper sections m ust rest squa rely on t he lower sections. When platforms ar e being moved to the n ext level, th e existing platforms must be left u ndistur bed unt il the new bear ers h ave been set in p lace and br aced, prior t o receiving the n ew platform s. Pole scaffolds over 60' in height mu st be designed by a r egistered pr ofessiona l engineer a nd m ust be constructed and loaded in accordance with that design. Bricklay er ’s Square
A brickla yer ’s squa re scaffold is a support ed scaffold composed of fra med squ ar es th at support a pla tform (see fi gure 16). These types scaffolds mu st n ot exceed th ree t iers in height an d be so const ru cted and ar ra nged tha t one square r ests directly above the other. Scaffolds ma de of wood m ust be rein forced with gussets on both sides of each corn er. Diagonal br aces must also be installed between squa res on th e rea r a nd front sides of the scaffold and must extend from th e bott om of each squa re to the t op of th e next squa re. The upper tiers of th e scaffold must sta nd on a cont inuous r ow of plank s laid across the n ext lower t ier an d na iled down or other wise secur ed to prevent displacement.
S u s p e n s i on S c a f fo l d s A suspension scaffold is one or m ore pla tform s susp ended by ropes or oth er n on-rigid mean s from an overhead stru ctur e(s). General Requirements
Ea ch scaffold an d scaffold component mu st be capable of supporting, without failur e, its own weight an d at least four times th e maximum intended load a pplied or t ra nsmitt ed to it. Ea ch su spension r ope, including conn ecting har dwar e, used on non-adjusta ble suspens ion scaffold mu st be capa ble of supporting, without failure, at least six times th e maximum intended load a pplied or t ra nsmitt ed to that rope. The st all load of an y scaffold must not exceed th ree t imes its r at ed load. C r i t e r i a f or s u s p e n s i o n s c a f f o l d s . All suspens ion scaffold su pport d evices must rest on s ur faces capable of supp ort ing at least four times t he load imposed on t hem by th e scaffold opera ting at th e ra ted load of the h oist (or a t least 1.5 times th e load imposed on t hem by the scaffold at th e sta ll capa city of th e hoist, whichever is great er). The scaffold su pport devices a re t hose such a s outr igger bea ms, corn ice hooks, par apet clam ps an d similar devices. Suspension scaffold out rigger beams, when u sed, must be made of stru ctur al meta l or equivalent st rength m ater ial and must be restra ined to prevent movement. The inboard ends of susp ension scaffold outr igger beam s m ust be sta bilized by bolts or oth er dir ect connections t o th e fl oor or r oof deck, or t hey mu st ha ve their inboard en ds st abilized by count erweights. However, masons ’ mu lti-point adjust able suspen sion scaffold outr igger beam s mu st n ot be stabilized by count erweights. Tiebacks mus t be used t o secur e out rigger beams th at ar e not sta bilized by bolts or oth er direct conn ections t o the fl oor or roof deck. Tiebacks must be equivalent in st ren gth t o th e suspen sion r opes. Before t he scaffold is used, a compet ent person m ust evalua te dir ect connections t o con fi r m t h a t t h e support ing surfaces ar e capa ble of supp ort ing the loads t o be imposed. In addit ion, as r elated t o ma sons mu lti-point adjust able suspen sion scaffold, connections m ust be designed by a n en gineer experienced in su ch scaffold design. 24
Count erweights must be secured by mecha nical mea ns t o the outrigger beam s to prevent a ccidental displacement; counter weight s mu st n ot be rem oved from an outr igger beam un til the scaffold is disassembled. Support devices su ch a s corn ice h ooks, roof hooks, r oof irons, pa ra pet clam ps or sim ilar devices mu st be made of steel, wrought iron or materials of equivalent strength. They must be supported by bearing blocks and s ecur ed again st m ovemen t by tiebacks insta lled at r ight a ngles to the face of the building or stru ctur e. Sound points of anchora ge include str uctura l members, but do not include sta ndpipes, vents, other piping systems or electr ical condu it. Tiebacks must be equivalent in str ength to the hoisting rope. Suspension scaffold power-operated hoists and manual hoists must be tested and listed by a quali fi ed test ing labora tory. Gasoline powered equipm ent an d hoists mu st n ot be used on su spension scaffolds. Gear s an d bra kes of power-opera ted h oist u sed on suspen sion scaffolds mu st be en closed. In addition to the normal operating brake, suspension scaffold power-operated hoists and manually operated hoists must have a braking device or locking pawl that engages when the hoist exceeds normal descent speed (mak es either a n inst an tan eous chan ge in momentum or an accelera ted over-speed). Man ua lly opera ted h oists r equire a positive cra nk force to descend. At least four wra ps of suspen sion r ope must be maint ained a t t he lowest point of scaffold tra vel when winding drum hoists a re u sed. When other types of hoists ar e used, th e suspen sion r opes must be of suf fi cient lengt h t o allow th e scaffold t o be lowered without the r ope end passing thr ough th e hoist, or t he rope end must be designed to prevent t he end from passing th rough th e hoist. Suspen sion r opes support ing adjusta ble suspension scaffolds must be of a diam eter la rge enough to provide su f fi cient sur face ar ea for pr oper fun ctioning of bra ke an d hoist mechan isms. Wire susp ension rope ma y only be joined t ogether by eye splice thimbles conn ected with sh ackles or coverplat es a nd bolts. Load en ds of wire suspen sion r opes mu st be equ ipped with pr oper size th imbles and secured by eye-splicing or equivalent mea ns. Swaged at ta chment s or spliced eyes on wire sus pension rope must be ma de by a wire rope man ufactur er or qualifi ed person. Wire rope clips mu st be ret ightened a fter initial loading an d inspected an d ret ightened r egular ly. Repair of a defective or da ma ged wire r ope is pr ohibited. S i n g l e - p o i n t A d ju s t a b l e ( B o a t s w a i n ’s C h a i r s )
A single-point adjust able su spension scaffold is a suspen sion scaffold consist ing of a plat form suspen ded by one r ope from a n overhea d support a nd equipped with mean s to permit t he movement of the platform to desired work levels (see fi gure 14). The su pporting r ope for t he scaffold mu st r ema in vert ical from th e scaffold an d sus pension device. Tackle for a boat swain ’s chair m ust ha ve the corr ect size ballbearing or bush ed blocks and p roperly eye5 spliced fi rst grade ma nila rope of at least ⁄ 8 ". Seat slings must be reeved thr ough four corn er holes in t he seat , crossed on t he un derside of th e seat a nd r igged to prevent slippage. Seat slings must be of at least 5 ⁄ 8 " fi ber or synth etic rope or its equ ivalent, except wh en employees ar e using a h eat producing process 3 (e.g., gas or ar c welding), th en wir e r ope of at least ⁄ 8 " mu st be used. Boat swain ’s cha irs tha t a re not crosslamin at ed wood mu st be reinforced on th e under side by cleats t o prevent splitting. When two single-point suspen sion scaffolds ar e joined t o crea te a two-point suspen sion scaffold, the scaffold mu st meet th e r equirem ent s of a two-point scaffold. Powered single-point adjust able scaffolds 5 will require t he use of a m inimum ⁄ 16 " diamet er wire rope and h oists r at ed by a n at iona lly recognized laboratory. Tw o - p o i n t A d ju s t a b l e ( S w i n g S t a g e )
A two-point suspension scaffold (swing stage) is a suspension scaffold consisting of a platform supported by han gers (stirru ps) suspended by two ropes from overhea d supports a nd equipped with mea ns t o perm it th e ra ising and lowering of th e platform to desired work levels (see fi gure 9). Platforms may n ot be more tha n t hr ee feet wide unless designed by a qua lifi ed person to prevent un sta ble condit ions. Pla tform s can be ladder-type, plank -type, beam -type, light met al-type or m odula rtr uss t ype. The light met al-type should be tested a nd listed by a na tionally recognized labora tory.
25
Plat form s mu st be secured t o ha ngers (stirr ups) by U-bolts or equivalent m ean s. The blocks for fi be r an d synt het ic ropes mu st consist of a minimu m of one double an d one single block. The sh eaves mu st fi t th e size of rope. The scaffolds mu st be t ied or secur ed by oth er m ean s to prevent swaying. Scaffolds specially designed as two-point scaffolds ma y not be connected t ogether dur ing r aising a nd lowering operations. Two-point scaffolds designed for use in multiple-point scaffolds can be bridged together if the conn ections a re a rt iculat ed an d th e hoist is seized properly. Pass age between one plat form to another is permissible only when t he platforms ar e at the same h eight, closely abutt ed, and wa lkthr ough st irrups specially designed for this pu rpose are used. Multiple-point Adjust able
A multiple-point adjust able su spension scaffold is a suspen sion scaffold consistin g of a plat form (s) suspended by more th an two ropes from overhead supports a nd equipped with mean s to permit th e ra ising an d lowering of th e plat form to desired work levels (see fi gure 10). A stone sett er ’s multiple-point adjustable suspension scaffold is a two-point or multiple-point adjustable suspension scaffold designed and used for stone setting operations. A mason ’s adjustable suspension scaffold is a two-point or multiple-point adjustable suspension scaffold designed and used for masonry operations. Two or more scaffolds m ay n ot be bridged t ogether un less specially designed to be br idged, the br idge conn ections ar e ar ticulated, an d th e hoists a re seized properly. If bridges are n ot used, passa ge may be ma de from one plat form if th e platform s ar e at t he sa me height a nd closely abu tt ed. Scaffolds must be suspen ded from meta l out riggers, iron bra ckets, wire rope slings, iron hooks or equa l mean s. Scaffold connections for ma son ’s adjust able susp ension scaffolds mu st be designed by an engineer exper ienced in scaffold des ign. Multi-level
A multi-level suspen ded scaffold is a two-point or mu ltiple-point adjust able su spension scaffold with a series of platforms at various levels su pported by common st irru ps (see fi gure 11). Such scaffolds m ust ha ve added independent support lines equal to th e number of points su pport ed and equal in str ength t o the suspension lines. Independent su pport lines an d suspension ropes ma y not be at tached to th e same a nchorage points. Platform su pports must be atta ched to the su pport stirru p an d not to any oth er platform. Catenary
A cat ena ry scaffold is a su spen sion scaffold consisting of a p lat form fasten ed to two essent ially horizonta l and pa ra llel ropes, which are secured to str uctur al member s. Horizont al ropes are u sua lly support ed by interm ediate vertical pickup ropes to reduce sag an d an chora ge load (see fi gur e 20). Only one platform ma y be placed between consecutive vert ical pickups an d no more th an two plat form s ma ybe used. Wire rope supported platforms must have hook-shaped stops on each end. Hooks must be situated to prevent the platform from falling in the event that one wire rope breaks. Supporting ropes should be 1 equal to ⁄ 2 " improved plow steel wire rope. Car e mu st be t ak en t o prevent overtighten ing of wire r opes, which can cau se excessive force at an chora ges an d overst ressing by t he scaffold load. Wire ropes mu st be cont inuous with out splices between a nchors. Float (Ship)
A fl oat (ship) scaffold is a suspen sion scaffold consist ing of a bra ced plat form rest ing upon two par allel bearers an d hu ng from overh ead supports by ropes of fi xed length (see fi gure 23). The platform must be supported by at least t wo bearer s, each pr ojecting a minimum of six inches beyond th e platform . Support r opes must be equa l in str ength t o at least 1" fi rst grade man ila r ope. Rope conn ections m ust be ma de to ensur e th at th e platform will not shift or slip. If only two ropes ar e used for ea ch fl oat , they must be arr an ged to supply four ends, which a re securely atta ched to overhead supports. Each supporting rope must be hitched ar oun d one end of th e bearer a nd pass un der th e plat form to the other end of th e bearer where it is h itched a gain, leaving suf fi cient r ope at each end for t he supporting ties. 26
Interior Hung
An inter ior hu ng scaffold is a suspen sion scaffold consist ing of a plat form suspen ded from t he ceiling or roof str uctur e by fi xed length support s (see fi gure 19). Such scaffolds ar e to be suspen ded only from t he r oof stru ctu re or other str uctur al m embers (e.g., ceiling beams). Overhead supporting m embers requir e inspection for str ength before scaffold erection. Su spension ropes and cable must be connected to the supportin g members by sha ckles, clips, th imbles or equa l mean s. Needle Beam
A needle beam scaffold is a suspen sion scaffold consist ing of a platform su pported by needle beam s (see fi gure 18). Scaffold support beam s mu st be insta lled on th e edges (nar row side). Ropes an d ha ngers m ust be used for su pport, with t he exception th at one end of th e scaffold can be supp ort ed by a solid, perm an ent str uctur al member. Support ropes must be equal in strength to at least 1" fi rst grade ma nila rope. Ropes must be secur ely att ached to needle beams. The support conn ection m ust be arr an ged to prevent the needle beam from r olling or being displaced. Platform s mu st be secur ely att ached t o needle beam s by bolts or equal means.
S p e c i a l U s e S c a f fo l d s Scaffolds and a ssembly must be capa ble of support ing their own weight a nd a t least four times t he maximum intended load applied or t ra nsmitted to the scaffold and components. F o r m a n d C a rp e n t e r B r a c k e t
A form scaffold is a su pported scaffold consist ing of a platform su pported by br ackets at ta ched to a form work . A car pent er ’s br acket scaffold is a support ed scaffold consist ing of a platform su pported by brackets at ta ched to building or stru ctur al walls. Each bra cket mu st be att ached to the supporting formwork or stru ctur e by mean s of na ils, a meta l stud at tachment device, welding or hooking each bra cket over a secur ed str uctura l supporting member with th e form walers bolted to th e form or fast ened by snap t ies or t ie bolts exten ding thr ough the form an d securely anchored. On carpenter ’s bra cket scaffolds, the t ie bolts can extend t hr ough th e opposite side of the structure ’s wa ll (see fi gure 15). Wooden bra cket form scaffolds mu st be a n int egral pa rt of th e form pan el. Folding metal bra ckets mu st be bolted or secured with a locking pin. Roof Bracket
A roof bracket scaffold is a rooftop su pported scaffold consistin g of a plat form support ed by t ria ngula r shaped supports. Bra ckets mu st conform to the pitch of th e roof and pr oduce a level support for t he plat form . Brackets 3 4 " fi r st should be secur ed in place by na ils. When n ails ar e not pra ctical, bra ckets should be anchored by ⁄ grade ma nila rope or its equivalent. Outrigger
An outr igger scaffold is a support ed scaffold consist ing of a plat form support ed by outr igger beam s (thr ust out s) projecting beyond t he wa ll or face of a building or str uctur e with t he inboard en ds secured inside the building or structure (see fi gure 7). An out rigger scaffold an d component s mu st be const ru cted an d loaded according to speci fi c con fi g u r a tions of the required standards or designed by a registered professional engineer and built and loaded according to th e design. 1 The length of th e out rigger beam s may not be less th an 1 ⁄ 2 times th e length of the out board end measur ed from th e fulcrum point t o th e extr eme point of an chora ge. The beams m ust rest on the edge (na rr ow side) with t he sides plum b an d th e edges horizont al. The fulcrum point is to rest on secure six-inch bearings. Beams m ust be secured t o prevent movement a nd bra ced at th e fulcrum point to prevent tipping.
27
Inboar d ends must be securely an chored by braced stru ts bear ing against sills conta cting overhead beam s or t he ceiling, or tension member s secur ed to the fl oor joists un derfoot, or both , as necessar y. The supporting structur e must be braced to eliminat e any h orizonta l movement. Platform units m ust be na iled, bolted or other wise fi rmly af fi xed to out riggers. The front en d of th e plat form mu st be positioned no more th an thr ee inches from the str ucture. Pump Jack
A pump jack scaffold is a support ed scaffold consist ing of a plat form support ed by vert ical poles an d movable support bra ckets (see fi gure 24). Bra ckets, braces an d accessories for pump jack scaffolds must be fabr icat ed from met al plat es an d an gles. Two positive gripping devices are r equired for ea ch bra cket. Poles mu st be secur ed to str uctur es by rigid trian gular bra cing or its equivalent at the bottom, top, and other points. When it is necessar y to raise th e platform , crossbra cing mu st be a dded about four feet on t he side opposite the pu mp jack brace and be left in place until the pu mp jack has been moved an d th e initial bra ce has been reinstalled. If wood poles are used, the lumber must be straight-grained, free of shakes and lar ge loose or dead kn ots an d oth er imper fections th at ma y reduce th e str ength of th e wood. If two consecut ive lengths a re us ed to form th e wood poles, th e poles are t o be conn ected togeth er with t he seam par allel to th e bra cket. If 2" x 4" lumber is u sed to crea te a pole, th e splices mu st be str ong enough to main ta in th e full str ength of the m ember. Workbenches ma y not be used a s scaffold plat form s. Ladder Jack
A ladder jack scaffold is a support ed scaffold consistin g of a plat form support ed by bra ckets a tt ached t o ladder s (see fi gure 21). The ma ximum a llowable height for a ladder jack scaffold is 20 feet. Only man ufactur ed ladder s ma y be used. Ladders mu st meet required sta ndar ds. Ladders supporting ladder jacks must be situa ted, fasten ed or conta in devices to prevent s lipping. The ladder jack must be designed a nd u sed so th at it bear s only on the side ra ils or only on t he ladder r ungs. If on t he ru ngs, the conta ct on each ru ng must be a minimum of 10 inches. Plat form s mu st be at least 12 inches wide an d ma y not be bridged one to an oth er. Wi n d o w J a c k
A window jack scaffold is a support ed scaffold consistin g of a plat form support ed by a bra cket or jack th at projects t hr ough a window opening (see fi gure 22). Window jack scaffolds mu st be securely at ta ched to window openings. Use should be r estr icted t o the work only at t he window opening. J acks ma y not be used to support oth er t ypes of scaffolding an d plank s or platform s placed between one window jack a nd a nother window jack. Horse
A horse scaffold mea ns a support ed scaffold consistin g of a platform su pported by const ru ction horses (see fi gure 17). Horse scaffolds mu st be built t o a height of no more 10 feet or two tiers, wh ichever is less. When tiers ar e used, ea ch horse mu st be pla ced imm ediately over t he h orse of the lower t ier. The legs of each h orse mu st be na iled to prevent dislocation. Each tier mu st be crossbra ced. Crawling Boards
A cra wling board (chicken ladder ) is a supp ort ed scaffold consist ing of a plank with cleats spaced an d secured to provide footing for use on sloped surfaces such as roofs. Dur ing roof const ru ction or repa ir or maint ena nce, crawling boar ds mu st exten d from th e roof peak t o th e eaves. Crawling boar ds mu st be secured t o th e roof by ridge hooks or equ al mea ns. S t e p , P l a t f o r m a n d Tr e s t l e L a d d e r
A step, platform an d t rest le ladder scaffold is a support ed scaffold consist ing of a plat form support ed directly on t he r un gs of step lad ders or a building wall. 28
Platforms may n ot be placed higher tha n t he second h ighest ru ng or step of the supporting ladder. Ladder s mu st be located, secured or cont ain devices to aver t slipping. Scaffolds ma y not be bridged one to another. Aerial Lifts G e n e r a l r e q u i r e m e n t s : Aerial lifts include the following types of vehicle-mounted aerial devices used to elevat e personn el to job-sites a bove groun d: exten sible boom platform s, aer ial ladders , ar ticulatin g boom pla tform s, vertical towers a nd a combina tion of an y of this equipmen t. Aerial equipment ma y be made of metal, wood, fi berglass rein forced plastic (FRP ) or oth er ma ter ial. It may be powered or ma nu ally operat ed. Such equipment an d/or devices ar e deemed to be aer ial lifts wheth er or not th ey are capable of rota ting about a subst an tia lly vertical axis. Aerial lifts a cquired for u se on or after J an . 22, 1973, mu st be designed and const ru cted in conform an ce with t he ap plicable requir ement s of Amer ican Na tional Sta ndar ds for “Vehicle Moun ted E levat ing an d Rotat ing Work Pla tform s, ” ANSI A92.2-1969, includin g appendix.
Aerial lifts ma y be “field modi fi ed ” for u ses other tha n t hose inten ded by the man ufactur er pr ovided the m odi fi cat ion h as been certi fi ed in writing by the m anu facturer or by any other equivalent entity (such as a na tionally recognized test ing labora tory). The modi fi cation(s) to aer ial lifts sh ould be done in m an ner to be in conformity with all applicable provisions of ANSI A92.2-1969 and appropriate section of OSHA sta nda rds (i.e., 1926.453) to be at least as sa fe as t he equipm ent was before m odifi cation. S p e c ifi c r e q u i r e m e n t s :
L a d d e r t r u c k s a n d t o w e r t r u c k s . Aerial ladder s mu st be secured in t he lower t ra veling position by th e locking device on t op of th e tr uck cab/an d th e ma nu ally opera ted device at th e base of th e ladder before t he tr uck is removed for t he highwa y tra vel. E xt e n s i b l e a n d a r t i c u l a t i n g b o om p l a t f o r m s . Lift cont rols must be test ed each day prior to use to deter mine t ha t su ch cont rols are in sa fe work ing condition. Only aut horized individuals can operat e an aer ial lift. Belting off to an adjacent pole, str uctur e or equipmen t wh ile working from a n a erial lift is n ot permitted. Em ployees ar e required to always stand fi rmly on t he fl oor of th e bask et. The employee mu st not sit or climb on th e edge of the ba sket or u se plan ks, ladder s or other devices for a work position. A body belt m ust be worn an d a lanyard at tached to th e boom or bask et when working from a n a erial lift. (Note: Body belt(s) can serve a s a positioning device; body belts ar e not a ccepta ble as pa rt of a per sonal fall arr est system.) Boom a nd ba sket load limits s pecifi ed by the m anu facturer must not be exceeded. The brakes mu st be set a nd wh en outr iggers a re u sed, they mu st be positioned on pads or a solid surface. Wheel chocks must be insta lled before u sing an aer ial lift on a n incline, provided th ey can be safely insta lled. An a erial lift tr uck mus t not be moved when t he boom is elevat ed in a work ing position with m en in th e basket , except for equipment th at is speci fi cally designed for this type of operation. Art iculat ing boom and exten sible boom plat form s, prima rily designed as per sonnel car riers, mu st h ave both plat form (upper) and lower contr ols. Upper cont rols must be in or beside th e platform within ea sy rea ch of the opera tor. Lower cont rols must provide for overriding th e upper cont rols. Cont rols must be plainly mar ked as t o th eir function. Lower level cont rols must n ot be opera ted un less permission h as been obta ined from t he em ployee in t he lift, except in case of emergency. Climbers can not be worn while perform ing work from an aer ial lift. The insu lated port ion of an aer ial lift must not be alter ed in any ma nn er t ha t m ight redu ce its insula ting value. Before moving an a erial lift for t ra vel, th e boom(s) mu st be inspected t o see tha t it is properly cra dled and outr iggers a re in stowed position (except as perm itted otherwise by this section of th e safety sta nda rd).
29
Glossary Aerial Devi ce. Any vehicle moun ted, t elescoping or a rt iculat ing, or both , used t o position p ersonn el (workers). Aerial Ladder. An aerial device consisting of a single- or multiple-section extensible ladder. Articulatin g Boom Platform . An aeria l device with two or m ore hinged boom sections. Bearer. A horizont al tr an sverse scaffold mem ber (which m ay be support ed by ledgers or ru nn ers) upon which th e scaffold platform rest s an d joins scaffold upr ights, posts, poles and similar m embers . Brace. A tie tha t h olds one scaffold member in a fi xed position with respect t o an other m ember. Brace also mean s a rigid type of conn ection holding a scaffold t o a building or str uctu re. Cleat. A structur al member used at the ends of platform units to prevent th e un its from slipping off th eir su pports. Cleat s ar e also used to provide footing on sloped sur faces such a s crawling boar ds. Coupler. A device for locking together the component tubes of a tube and coupler scaffold. Equivalent. An a lterna tive design, ma terial or meth od th at the em ployer can demonstr ate will provide an equa l or grea ter degree of safety for employees tha n t he met hod or item specifi ed in th e standard. Extensible Boom Platform . An aerial device (except ladders) with a telescopic or extensible boom. Telescopic derr icks with personn el platform at ta chment s a re consider ed to be extensible boom pla tform s when u sed with a per sonnel platform. Harness. A design of str aps th at is secur ed about the employee in a ma nner to distribute t he ar resting forces over at least th e th ighs, shoulders a nd pelvis, with provisions for a tt aching a lanya rd, lifeline or deceleration device. Hoist. A mechan ical device to raise or lower a suspen ded scaffold. It can be mechan ically powered or man ually operat ed. Insu lated A erial Device. An a erial device designed for work on energized lines an d appa ra tu s. Ladder Stand. A mobile, th e form of sta irs.
fi xed-size,
self-supporting ladder that appears as a wide
fl at
tread ladder in
Ledger. A horizont al scaffold member upon which bearer s rest . It is the longitu dinal mem ber th at joins scaffold upr ights, posts, poles an d similar member s. Maximu m In tended Load. The tota l load of all employees, equipmen t, tools, mat erials, tr an smitt ed loads, wind loads, a nd other loads rea sonably an ticipat ed t o be applied to a scaffold or scaffold component at a ny one time. Mecha nically Powered H oist. A hoist th at is powered by other tha n h uma n en ergy. Outrigger. The st ru ctur al mem ber of a su pported scaffold used t o increase t he ba se width of a scaffold in order to provide grea ter sta bility for t he scaffold. Outrigger B eam. The st ru ctur al m ember of a suspen sion scaffold or outr igger scaffold th at provides support for t he scaffold by exten ding th e scaffold point of at ta chment to a point out an d awa y from th e stru ctur e or building. Personal Fall Arrest S ystem . A system used t o arr est a n em ployee in a fall from a work ing level. It consists of an an chora ge, conn ectors, a body belt or body har ness a nd m ay include a lan yar d, decelerat ion device, lifeline or suit able combina tions of th ese. The u se of a body belt for fall arr est is prohibited. Platform. The horizontal working surface of a scaffold. Platform. Any personnel-carrying device (basket or bucket) that is a component of an aerial device. Platform Unit. The individua l wood plan ks, fabricat ed plank s, fabricated decks a nd fabricated pla tform s th at compose the platform s a nd walkways of a scaffold.
30
Positioning Device System. A body belt or body ha rn ess system rigged to allow an employee to be supported on an elevat ed vertical surface, such as a wall, an d work with both h an ds free while leaning. Runner. The lengthwise horizonta l bracing or bearing member tha t su pport s bearer s on tu be and coupler scaffolds. Scaffold. Any temporar y elevated or suspended platform an d its supporting stru ctur e used for su pport ing employees or materials or both, except this term does not include crane or derrick suspended personnel platforms. S cissor L ift. A self-propelled or m an ua lly propelled lifting per sonnel plat form (within wheel base) capa ble of vert ical m ovemen t with onboar d cont rols as de fi ned by ANSI/SIA A92.6-1990. Vertical Pickup . A rope used to support th e horizont al r ope in cat ena ry scaffolds. Walkway. A port ion of a scaffold pla tform u sed only for a ccess a nd is not a work level. Work Level. An elevated plat form u sed for su pporting employees an d th eir ma ter ials where work activities ar e performed.
31
References Cloe, William W. May 1979. Occupational Fatalities Related to Scaffolds as Found in Reports of OSHA Fatality/Catastrophe Investigations. U.S. Department of Labor, Occupational Safety and Health Administration. Construction Safety Association of Ontario. September/October 1990. “Suspended Access.” Construction Safety. Construction Safety Association of Ontario. Ellis, Nigel J. January 1983. “Suspended Scaffolding: Proper Protection Reduces Fall Injuries.” Occupational Health & Safety. “Fall Protection.” July 1990. Construction Safety. Construction Safety Association of Ontario. Hinson, J. R. October 1988. “Careful Selection, Use of Scaffolds Imperative to Accident Prevention.” Occupational Health and Safety. International Labor Organization. 1983. “Scaffolding.” Encyclopedia of Occupational Health & Safety , vol. II, L–Z, International Labor Organization. Kliwinski, D. P. October 1988. “Elevated Workplaces: Ladders and Scaffolds.” Center for Excellence in Construction Safety Newsletter . West Virginia University, Center for Excellence in Excavation. Morgantown, WV. National Safety Council. 1980. Accident Prevention Manual for Industrial Operations . 8th ed. Edited by F. E. McElroy. Chicago: NSC. N.C. Department of Labor. 1999. North Carolina Occupational Safety and Health Standards for General Industry . Subpart D—Walking-Working Surfaces; Subpart F—Powered Platforms, Manlifts, and Vehicle-Mounted Work Platforms. N.C. Department of Labor, Occupational Safety and Health Division. Raleigh. N.C. Department of Labor. 1994. North Carolina Occupational Safety and Health Standards for the Construction Industry. Subpart L—Scaffolding. N.C. Department of Labor, Occupational Safety and Health Division. Raleigh. Potts, D. L. 1985. “An Assessment of Carpenter’s Injury Risks Needing Research.” NIOSH Report: DSR-85-0458 O.M. National Constructors Association. Potts, D. L. Spring 1991. “Fall Prevention and Protection.” Excel , vol. 4, no. 3. West Virginia University, Center for Excellence in Construction Safety. Morgantown, WV. U.S. Department of Labor, OSHA 3150, 2000 (Reprinted); A Guide to Scaffold Use in the Construction Industry. U.S. Department of Labor. May 1983. “Survey of Scaffold Accidents Resulting in Injuries, 1978.” U.S. Department of Labor, Bureau of Labor Statistics.
32
The following industry guides are available from the N.C. Department of Labor’s Occupational Safety and Health Division:
1#1. A Guide to Safety in Confined Spaces 1#2. A Guide to Procedures of the N.C. Safety and Health Review Commission (downloadable PDF ONLY) 1#3. A Guide to Machine Safeguarding 1#4. A Guide to OSHA in North Carolina 1#5. A Guide for Persons Employed in Cotton Dust Environments (downloadable PDF ONLY) 1#6. A Guide to Lead Exposure in the Construction Industry (downloadable PDF ONLY) 1#7. A Guide to Bloodborne Pathogens in the Workplace 1#8. A Guide to Voluntary Training and Training Requirements in OSHA Standards 1#9. A Guide to Ergonomics #10. A Guide to Farm Safety and Health (downloadable PDF ONLY) #11. A Guide to Radio Frequency Hazards With Electric Detonators (downloadable PDF ONLY) #12. A Guide to Forklift Operator Training #13. A Guide to the Safe Storage of Explosive Materials (downloadable PDF ONLY) #14. A Guide to the OSHA Excavations Standard #15. A Guide to Developing and Maintaining an Effective Hearing Conservation Program #16. A Guide to Construction Jobsite Safety and Health/Guía de Seguridad y Salud para el Trabajo de Construcción #17. A Guide to Asbestos for Industry #18. A Guide to Electrical Safety #19. A Guide to Occupational Exposure to Wood, Wood Dust and Combustible Dust Hazards (downloadable PDF ONLY) #20. A Guide to Cranes and Derricks #23. A Guide to Working With Electricity #25. A Guide to Personal Protective Equipment #26. A Guide to Manual Materials Handling and Back Safety #27. A Guide to the Control of Hazardous Energy (Lockout/Tagout) #28. A Guide to Eye Wash and Safety Shower Facilities #29. A Guide to Safety and Health in Feed and Grain Mills (downloadable PDF ONLY) #30. A Guide to Working With Corrosive Substances (downloadable PDF ONLY) #31. A Guide to Formaldehyde (downloadable PDF ONLY) #32. A Guide to Fall Prevention in Industry #32s. Guía de Prevención de las Caídas en la Industria (Spanish version of #32) #33. A Guide to Office Safety and Health (downloadable PDF ONLY) #34. A Guide to Safety and Health in the Poultry Industry (downloadable PDF ONLY) #35. A Guide to Preventing Heat Stress #38. A Guide to Safe Scaffolding #40. A Guide to Emergency Action Planning #41. A Guide to OSHA for Small Businesses in North Carolina #41s. Guía OSHA para Pequeños Negocios en Carolina del Norte (Spanish version of #41) #42. A Guide to Transportation Safety #43. A Guide to Combustible Dusts #44. A Guide to Respiratory Protection
