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Scaffolds

Work activities associated with scaffolds are subject to many hazards; however, falls are by far the number-one cause of injury or death among construction workers. The following requirements regulate the design, erection, dismantling, and use of scaffolds:

A. General requirements

1. Scaffolds must be provided for work that cannot be done safely by employees standing on ladders or on solid construction that is at least 20 in. wide.
   

   Exception: A 12-inch wide plank on members that are on 24 inch (or closer) centers is permitted. 1637(a)

2. The design of scaffolds must conform to design standards, or scaffolds must be designed by a licensed engineer. Standards are based on stress grade lumber. Metal or aluminum may be substituted if the structural integrity of the scaffold is maintained. 1637(b)
   
3. Each scaffold must be designed to support its own weight and 4 times the maxim load. Maximum working loads are as follows: 1637(b)
   
   1. Light-duty scaffolds: 25 psf of work platform.
      
   2. Medium-duty scaffolds: 50 psf of work platform.
      
   3. Heavy-duty scaffolds: 75 psf of work platform.
      
   4. Special-duty scaffolds exceeding 75 psf as determined by a qualified person or a California registered Civil Engineer with scaffold design experience.
      
4. The erecting and dismantling of scaffolds are regulated as follows:
   
   1. Scaffold erection and dismantlement must be supervised by a qualified person. 1637(k)(1)
      
   2. Scaffolds must be erected and dismantled according to design standards, engineered specifications, or manufacturer’s instructions. 3328, 1637(k)
      
   3. A DOSH permit is required for erecting and dismantling scaffolds that exceed three stories or 36 ft. in height. 341(d)(5)(B)
      
5. Scaffold access: Ladders, horizontal members, and stairways must provide safe and unobstructed access to all platforms. The equipment must be located so that its use will not disturb the stability of the Scaffold: 1637(n)
   
   1. Ladders may be used if the following applies:
      

      April 2007 Update Scaffolds Section 1637, General Requirements: Manufactured hook-on ladders shall be securely attached to the scaffold, must be designed for the type of scaffold used, have a minimum rung length of 11-1/2 inches, and be uniformly spaced with maximum spacing between rungs of 16-3/4 inches. http://www.dir.ca.gov/Title8/1637.html

      1. Ladder use must comply with Article 25 in the CSOs.
         
      2. Ladders must be securely attached to scaffolds.
         
      3. Ladders must extend 3 ft. above the platform, or handholds must be provided. 1675(i)
         
   2. Horizontal members built into the end frame of a scaffold may be used to access platforms if the following applies:
      
      1. The horizontal members are parallel and level.
         
      2. The horizontal members make a continuous ladder, bottom to top, With the ladder sides of the frames in a vertical line.
         
      3. The horizontal members provide sufficient clearance for a good handhold and foot space. 1637(n), 1644(a)
         
   3. Stairways must conform to the following:
      
      1. Permanent stairways must comply with GISO requirements. 1637(n)(2)
         
      2. Prefabricated scaffold stairs must comply with ANSI 10.8-1988. 1637(n)(2)
         
6. Scaffolds must be secured as follows:
   
   1. Scaffolds must be tied off with a double- looped No. 12 iron wire or a single- looped No. 10 iron wire or the equivalent. A compression member should prevent scaffold movement toward the structure. 1640, 1641, 1644
      
   2. Light duty wooden pole scaffolds must be tied off every 20-ft. horizontally and vertically. 1640(b)
      
   3. Heavy-trade wooden pole scaffolds must be tied off every 15-ft. horizontally and vertically. 1641(f)
      
   4. Metal scaffolds must be tied off as specified in 1644(a)(5). 1644(a)(5)
      
7. Scaffold platforms must conform to the following:
   
   1. Platforms must be capable of supporting the intended load. 1644(a)(1), 1637(m)
   2. Platforms must be planked solid (without gaps) and cover the entire space between scaffold uprights. 1640(b), 1641(g), 1644(a), 1646(e)

      Exception: In solid planking the following gaps are permissible:

      A. The opening under the back railing
      

      1. Wood scaffolds: 8 in. (max.)horizontal. 1640(b)(5)
         
      2. Metal scaffolds: 10 in. (max.) horizontal. 1644(a)(7)
         

      B. Space between the building (structure) and the platform
      

      1. Wood scaffolds: 14 in.(max.). 1640(b)(5)
         
      2. Metal scaffolds: 16 in. (max.). 1644(a)(7)
         
      3. Bricklayers scaffolds: 7 in. (max.) to finished face of building. 1641(g)(2)

       

   3. Platform minimum widths are as follows:
      
      1. Light duty: 20 in. 1640(b)(5)
         
      2. Heavy trades: 4 ft. 1641(c)
         
   4. Platform slope must not exceed 2 ft. vertically to 10 ft. horizontally. 1637(o)
      
   5. Overhead protection is required when people are working overhead. 1637(q)
      
   6. Slippery platform conditions are prohibited. 1637(p)
      
8. Planking must conform as follows:
   
   1. Planking must be made of scaffold grade (structural plank 2200 Psi) lumber (see 1504) with a nominal dimension of 2” x 10”. 1637(f)(1)
      
   2. Planking shall not exceed a maximum span as follows:
      
      1. Light trades @ 25 psf = 10 ft.
         
      2. Medium trades @ 50 psf = 8 ft.
         
      3. Heavy trades @ 75 psf = 7 ft.
         
   3. Planking shall overhang the ledger or support as follows:
      
      1. A minimum of 6 in. 1640(b), 1645(b)
         
      2. A maximum of 18 in. 1637(g), 1645(b)
         
   4. A single plank (up to 4 ft. high) is only permitted on light-trade wooden pole and horse scaffolds. 1640(b)(5)(A) and 1647(e)(2)
      
9. Guardrails must be installed on open sides and ends of platforms that are 7 1/2 ft. or higher. 1621(a)

Exception: 1644(a)(6)(A),(B)


April 2007 Update Scaffolds Section 1644, Metal Scaffolds: “X” bracing is acceptable as a midrail if the intersection of the “X” falls between 20 and 30 inches (reduced from 36 inches) from the work platform. http://www.dir.ca.gov/Title8/1644.html

A. X braces that substitute for a midrail must intersect 20 in. to 36 in. above the platform.


B. X-braces that substitute for a top rail must intersect 42 in. to 48 in. above the platform, and a midrail must be placed at 19 in. to 25 in. above the platform.

10. Toeboards are required on all railed sides of work surfaces where employees work or pass below. 1621(b)
    
11. Height limits for scaffolding are as follows:
    
    1. Wood (frame/post) = 60 ft. 1643
       
    2. Tube and coupler = 125 ft. 1644(b)(4)
       
    3. Tubular (welded) = 125 ft. 1644(c)(7)
       
    4. Horse (single) = l0 ft. 1647(b)(2)
       
    5. Horse (tiered) = 10 ft. 1647(b)(2)

       Exception: These limits do not apply when the scaffolding is designed by an engineer (Ca PE).

12. Prohibited scaffolds and supports: 1637(j)
    
    1. Shore scaffolds
       
    2. Jack scaffolds (with brackets attached to single studs)
       
    3. Lean-to scaffolds
       
    4. Stilts
       
    5. Nailed brackets
       
    6. Brick or blocks
       
    7. Loose tile
       
    8. Unstable objects
       
13. Maximum scaffold working load must be posted or provided to and available from, jobsite supervisor. 1637(b)(6)
    
14. Prohibited work practices
    
    1. Work on or from scaffolds during storms or high winds unless:
       
       1. A qualified person has determined that it is safe and
          
       2. Employees are protected by a personal fall arrest system, or wind screens. 1637(u)
          

          Note: Wind screens shall not be used unless the scaffold is secured against the anticipated wind forces. 1637(u)

    2. Wood platforms shall not be painted with opaque finishes, but can be coated with certain clear finishes 1637(v)
       

B. Scaffold-specific requirements

The requirements listed below are unique to each type of scaffold listed, and they replace or augment the general requirements.

1. Tubular welded scaffold systems
   These scaffold systems are commercially fabricated and must meet the following requirements:
   
   1. Frames must nest with coupling or stacking pins to provide proper vertical alignment. 1644(c)(5)
      
   2. Frame panels must be vertically pinned if uplift may occur. 1644(c)(6)
      
2. Tower and rolling scaffolds
   The specifications for tower and rolling scaffolds are as follows:
   
   1. The “height-to-base” must not exceed 3:1 unless the scaffold is secured. 1646(a)
      
   2. The following conditions must exist if employees ride on a rolling scaffold:
      
      1. The minimum dimension of the scaffold base, when the scaffold is ready for rolling, is at least half of the height. If outriggers are used to meet this requirement, they must be installed on both sides of the staging.
         
      2. The floor or surface is within 3 of level and free from pits, holes, or obstructions.
         
      3. A rolling scaffold less than 50 ft. high must be equipped with rubber wheels or similarly resilient tires.
         Metal wheels may be used for towers 50 ft. or higher. 1646(f)
         
   3. A screw jack must extend 1/3 of its length into the leg tube, and the exposed thread must not exceed 12 in. 1646(b)(2)
      
   4. Two wheels, or casters, must swivel; all four must lock. 1646(c)
      
   5. A fully planked platform is required. 1646(e)
      
   6. All frame and center joints shall be locked together by lock pins, bolts, or equivalent fastenings. 1646(d)
      
   7. The scaffold must have horizontal diagonal bracing (see Illustration 9). 1646(b)
      
   8. Railings are required if the platform is 7 1/2 ft. or more above grade. 1646(b)
      
3. General requirements for suspended scaffolds (swing staging). (1658)
   Most suspended scaffolding has a two-point suspension supported by hangers or stirrups. The following applies:

   

   
   
   1. Each wire is suspended from a separate outrigger beam or thrustout. 1658(k)
   2. Multi-stage units or units with overhead protection must be equipped with additional suspension lines to support the scaffolding in case the primary suspension system fails. 1658(u)
   3. The scaffold must be inspected daily and tested frequently. 1658(g)
   4. All hoisting mechanisms and metal platforms must meet nationally recognized standards. 1658(a)
   5. Outrigger beams must be secured in a saddle and anchored at one end to solid structure. The inboard end must be tied back. 1658(j)
   6. The beam must be capable of supporting four times the intended load. 1658(j)(1)
   7. Use of a ladder as a platform is prohibited even if a horizontal work surface is added. 1658(d)
   8. The load limit is one person per suspension rope. 1660(a)
   9. An insulated wire suspension rope is required when workers are welding, sandblasting, or using acid or corrosive solutions. 1658(f)
   10. A separate safety harness and lifeline are required for each worker. 1658(i), 1660(g)
   11. Platform dimensions must be as follows:
       
       1. Width = 14 in. to 36 in. 1660(d) = 24 in. to 36 in. if the platform is used by cement masons. 1661(b)
          
       2. Span = 10 ft. (2” x 10” planks). 1660(e) = 12 ft. (2” x 12” planks). 1660(e)
          
       3. Bolster (ledger) = 2” x 4” cross section. 1660(c)
          
4. Specific requirements for suspended scaffolds
   
   1. Powered suspended scaffolds. 1667
      The general rules for swing scaffolds apply except as listed below:
      
      1. The minimum platform width must be 20 in. 1667(d)
         
      2. Railings are required on open sides and ends and on all sides if the scaffold is suspended by one rope. 1667(a)
         
      3. The load limit is 425 lbs. for a ladder-type platform. 1667(b)
         
      4. Controls must be of the dead-man type.
         
      5. Load release units for fast descent are prohibited. 1667(f)(1)
         
   2. Interior hung suspended scaffolds. 1665
      These scaffolds are of a wood- or steel-tube-and-coupler type, and they are suspended from a ceiling or roof structure. The general and suspended scaffold rules apply.

      Exception:
      A. Suspension ropes must be wrapped twice around supporting members and ledgers. 1665(b)
      B. Ends of wire rope must be secured with at least three clips.

   3. Float suspended scaffolds. 1663
      These scaffolds are intended for such work as welding, riveting, and bolting. 1663(a)
      
      1. Platform size: 3 ft. x 6 ft. x 3/4 in. plywood. 1663(a)(1)
         
      2. Rope: 1-in. diameter manila (min.). 1663(a)(4)
         
      3. Load limit: three people 1663(a)
         
      4. Personal fall protection and a separate lifeline: required for each person. 1663(a)(5)
         
   4. Boatswain’s chair. 1662
      The use of a boatswain’s chair requires training or experience. 1662(a)
      
      1. Platform size: 10 in. x 24 in. x 2 in. 1662(i)
         
      2. Rope: 5/8-in. diameter manila (min.) and 3/8-in. diameter protected wire for welding. 1662(j),(k)
         
      3. Personal fall protection and a separate lifeline: required 1662(c)
         
      4. Area below: barricaded. 1662(b)
         
   5. Needle Beam scaffolds. 1664
      The specifications for needle beam scaffolds are as follows:
      
      1. Beam size: 4 in. x 6 in. x 10 ft. 1664(a)(1)
         
      2. Rope: 1 1/4-in. diameter manila 1664(a)(4)
         
      3. Personal fall protection: required in accordance with Article 24 in the CSOs. 1664(a)(12)
         Note: See the hitches for holding needle beams in Illustration 10.

       

      
      

   6. Outrigger scaffolds. 1645
      Outrigger scaffolds are regulated as follows:
      
      1. Brackets or beams must be anchored or braced against turning, twisting, or tipping. 1645(a)(1)
         
      2. Platform: at least two 2 in. x 10 in. planks. 1645(a)(2), 1645(b)(5)
         
      3. Beam size: 3 in. x 12 in. (min.) 1645(a)(2)
         
      4. Beam length: Outboard of fulcrum must not exceed 6 ft; inboard must be 1 1/2 times the outboard section. 1645(a)(1)

      
      Note: For multi-level structures the units must be designed by an engineer (Ca PE). 1645(a)(3)

   7. Bracket scaffolds (light trades). 1645
      Brackets must be bolted through walls, welded to tanks, properly secured to metal studs, or hooked over a supporting member. 1645(d)
      
      1. Platform: 20 in. x 10 ft. (min.)
         
      2. Load limit: carpenter’s type = two workers and 75 lbs. of equipment. 1645(e)(4)
         
   8. Horse scaffolds. 1647
      The specifications for horse scaffolds are as follows:
      
      1. Platform width:
         
         1. Light trades = 20 in. (min.); 10 in. if the platform is less than 4 ft. high
            
         2. Heavy trades = 4 ft. (min.). 1647(e)(2)
            
      2. Width of base legs = 1/2 x height (min.). 1647(a)(3)
         
      3. Height:
         
         1. Collapsible horse = 6 ft. (max.) 1647(d)(2)
            
         2. Single horse = 10 ft. (max.). 1647(e)(1)
            
         3. Two tiers (max.) = 10 ft. (max.). 1647(e)(1)
            
   9. Ladder jack scaffolds. 1648
      The specifications for ladder jack scaffold platforms are as follows:
      
      1. Span = 16 ft. (max.) 1648(b)
         
      2. Height = 16 ft. (max.) 1648(a)
         
      3. Width = 14 in. (min.) 1648(b)
         
      4. Load = two workers (max.) 1648(a)

         Note:
         A. Ladders must be commercial grade. 1648(d)
         B. A safety line is required for each worker. 1648(c)

   10. Window jack scaffolds. 1654
       The specifications for window jack scaffolds are as follows:
       
       1. Only one window per scaffold is permitted. 1654(d)
          
       2. The load limit is one person per scaffold. 1654(d)
          
       3. Fall protection or railings are required. 1654(c)