Safety Information - Excerpt from OSHA Regulatory Text

Scaffold Safety (from OSHA §1926.451)

• (a) Capacity

  • (1) Except as provided in para-graphs (a)(2), (a)(3), (a)(4), (a)(5) and (g) of this section, each scaffold and scaffold component shall be capable of supporting, without failure, its own weight and at least 4 times the maximum intended load applied or transmitted to it.
  • (2) Direct connections to roofs and floors, and counterweights used to balance adjustable suspension scaffolds, shall be capable of resisting at least 4 times the tipping moment imposed by the scaffold operating at either the rated load of the hoist, or 1.5 (minimum) times the tipping moment imposed by the scaffold operating at the stall load of the hoist, whichever is greater.
  • (3) Each suspension rope, including connecting hardware, used on non-adjustable suspension scaffolds shall be capable of supporting, without failure, at least 6 times the maximum intended load applied or transmitted to that rope.
  • (4) Each suspension rope, including connecting hardware, used on adjustable suspension scaffolds shall be capable of supporting, without failure, at least 6 times the maximum intended load applied or transmitted to that rope with the scaffold operating at either the rated load of the hoist, or 2 (minimum) times the stall load of the hoist, whichever is greater.
  • (5) The stall load of any scaffold hoist shall not exceed 3 times its rated load.
  • (6) Scaffolds shall be designed by a qualified person and shall be constructed and loaded in accor-dance with that design. Non-mandatory Appendix A to this subpart contains examples of criteria that will enable an employer to comply with paragraph (a) of this section.

• (b) Scaffold platform construction.

  • (1) Each platform on all working levels of scaf-folds shall be fully planked or decked between the front uprights and the guardrail supports as follows:
    • (i) Each platform unit (e.g., scaffold plank, fabri-cated plank, fabricated deck, or fabricated platform) shall be installed so that the space between adjacent units and the space between the platform and the uprights is no more than 1 inch (2.5 cm) wide, except where the employer can demonstrate that a wider space is necessary (for example, to fit around uprights when side brackets are used to extend the width of the platform).
    • (ii) Where the employer makes the demonstration provided for in paragraph (b)(1)(i) of this section, the platform shall be planked or decked as fully as possible and the remaining open space between the platform and the uprights shall not exceed 9_ inches (24.1 cm). Exception to paragraph (b)(1): The requirement to provide full planking or decking does not apply to platforms used solely as walkways or solely by employees performing scaffold erection or disman-tling. In these situations, only the planking that the employer establishes is necessary to provide safe working conditions is required.
  • (2) Except as provided in paragraphs (b)(2)(i) and (b)(2)(ii) of this section, each scaffold platform and walkway shall be at least 18 inches (46 cm) wide.
    • (i) Each ladder jack scaffold, top plate bracket scaffold, roof bracket scaffold, and pump jack scaffold shall be at least 12 inches (30 cm) wide. There is no minimum width requirement for boatswains' chairs.
    • (ii) Where scaffolds must be used in areas that the employer can demonstrate are so narrow that plat-forms and walkways cannot be at least 18 inches (46 cm) wide, such platforms and walkways shall be as wide as feasible, and employees on those platforms and walkways shall be protected from fall hazards by the use of guardrails and/or personal fall arrest
  • (3) Except as provided in paragraphs (b)(3)(i) and (ii) of this section, the front edge of all plat-forms shall not be more than 14 inches (36 cm) from the face of the work, unless guardrail systems are erected along the front edge and/or personal fall arrest systems are used in accordance with para-graph (g) of this section to protect employees from falling.
    • (i) The maximum distance from the face for outrigger scaffolds shall be 3 inches (8 cm);
    • (ii) The maximum distance from the face for plastering and lathing operations shall be 18 inches (46 cm).
  • (4) Each end of a platform, unless cleated or otherwise restrained by hooks or equivalent means, shall extend over the centerline of its support at least 6 inches (15 cm).
  • (5)
    • (i) Each end of a platform 10 feet or less in length shall not extend over its support more than 12 inches (30 cm) unless the platform is designed and installed so that the cantilevered portion of the platform is able to support employees and/or materials without tipping, or has guardrails which block employee access to the cantilevered end.
    • (ii) Each platform greater than 10 feet in length shall not extend over its support more than 18 inches (46 cm), unless it is designed and installed so that the cantilevered portion of the platform is able to support employees without tipping, or has guardrails which block employee access to the cantilevered end.
  • (6) On scaffolds where scaffold planks are abutted to create a long platform, each abutted end shall rest on a separate support surface. This provision does not preclude the use of common support members, such as "T" sections, to support abutting planks, or hook on platforms designed to rest on common supports.
  • (7) On scaffolds where platforms are overlapped to create a long platform, the overlap shall occur only over supports, and shall not be less than 12 inches (30 cm) unless the platforms are nailed together or otherwise restrained to prevent move-ment.
  • (8) At all points of a scaffold where the platform changes direction, such as turning a corner, any platform that rests on a bearer at an angle other than a right angle shall be laid first, and platforms which rest at right angles over the same bearer shall be laid second, on top of the first platform. (1926.451(a) continued)
  • (9) Wood platforms shall not be covered with opaque finishes, except that platform edges may be covered or marked for identification. Platforms may be coated periodically with wood preservatives, fire-retardant finishes, and slip-resistant finishes; how-ever, the coating may not obscure the top or bottom wood surfaces.
  • (10) Scaffold components manufactured by different manufacturers shall not be intermixed unless the components fit together without force and the scaffold's structural integrity is maintained by the user. Scaffold components manufactured by differ-ent manufacturers shall not be modified in order to intermix them unless a competent person determines the resulting scaffold is structurally sound.
  • (11) Scaffold components made of dissimilar metals shall not be used together unless a competent person has determined that galvanic action will not reduce the strength of any component to a level below that required by paragraph (a)(1) of this section.

• (c) Criteria for supported scaffolds.

  • (1) Supported scaffolds with a height to base width (including outrigger supports, if used) ratio of more than four to one (4:1) shall be restrained from tipping by guying, tying, bracing, or equivalent means, as follows:
    • (i) Guys, ties, and braces shall be installed at locations where horizontal members support both inner and outer legs.
    • (ii) Guys, ties, and braces shall be installed according to the scaffold manufacturer's recommen-dations or at the closest horizontal member to the 4:1 height and be repeated vertically at locations of horizontal members every 20 feet (6.1 m) or less thereafter for scaffolds 3 feet (0.91 m) wide or less, and every 26 feet (7.9 m) or less thereafter for scaffolds greater than 3 feet (0.91 m) wide. The top guy, tie or brace of completed scaffolds shall be placed no further than the 4:1 height from the top. Such guys, ties and braces shall be installed at each end of the scaffold and at horizontal intervals not to exceed 30 feet (9.1 m) (measured from one end [not both] towards the other).
    • (iii) Ties, guys, braces, or outriggers shall be used to prevent the tipping of supported scaffolds in all circumstances where an eccentric load, such as a cantilevered work platform, is applied or is transmit-ted to the scaffold.
  • 2) Supported scaffold poles, legs, posts, frames, and uprights shall bear on base plates, mud sills or other adequate firm foundation.
    • (i) Footings shall be level, sound, rigid, and capable of supporting the loaded scaffold without settling or displacement.
    • (ii) Unstable objects shall not be used to support scaffolds or platform units.
    • (iii) Unstable objects shall not be used as working platforms.
    • (iv) Front-end loaders and similar pieces of equipment shall not be used to support scaffold platforms unless they have been specifically designed by the manufacturer for such use.
    • (v) Fork-lifts shall not be used to support scaf-fold platforms unless the entire platform is attached to the fork and the fork-lift is not moved horizon-tally while the platform is occupied.
  • (3) Supported scaffold poles, legs, posts, frames, and uprights shall be plumb and braced to prevent swaying and displacement.

• (d) Criteria for suspension scaffolds.

  • (1) All suspension scaffold support devices, such as outrigger beams, cornice hooks, parapet clamps, and similar devices, shall rest on surfaces capable of supporting at least 4 times the load imposed on them by the scaffold operating at the rated load of the hoist (or at least 1.5 times the load imposed on them by the scaffold at the stall capacity of the hoist, whichever is greater).
  • (2) Suspension scaffold outrigger beams, when used, shall be made of structural metal or equiva-lent strength material, and shall be restrained to prevent movement.
  • (3) The inboard ends of suspension scaffold outrigger beams shall be stabilized by bolts or other direct connections to the floor or roof deck, or they shall have their inboard ends stabilized by counter-weights, except masons' multi-point adjustable suspension scaffold outrigger beams shall not be stabilized by counterweights.
    • (i) Before the scaffold is used, direct connec-tions shall be evaluated by a competent person who shall confirm, based on the evaluation, that the supporting surfaces are capable of supporting the loads to be imposed. In addition, masons' multi-point adjustable suspension scaffold connections shall be designed by an engineer experienced in such scaffold design.
    • (ii) Counterweights shall be made of non-flowable material. Sand, gravel and similar materials that can (1926.451(b) continued) be easily dislocated shall not be used as counterweights.
    • (iii) Only those items specifically designed as counterweights shall be used to counterweight scaf-fold systems. Construction materials such as, but not limited to, masonry units and rolls of roofing felt, shall not be used as counterweights.
    • (iv) Counterweights shall be secured by mechanical means to the outrigger beams to prevent accidental displacement.
    • (v) Counterweights shall not be removed from an outrigger beam until the scaffold is disassembled.
    • (vi) Outrigger beams which are not stabilized by bolts or other direct connections to the floor or roof deck shall be secured by tiebacks.
    • (vii) Tiebacks shall be equivalent in strength to the suspension ropes.
    • (viii) Outrigger beams shall be placed perpendicu-lar to its bearing support (usually the face of the building or structure). However, where the employer can demonstrate that it is not possible to place an outrigger beam perpendicular to the face of the building or structure because of obstructions that cannot be moved, the outrigger beam may be placed at some other angle, provided opposing angle tiebacks are used.
    • (ix) Tiebacks shall be secured to a structurally sound anchorage on the building or structure. Sound anchorages include structural members, but do not include standpipes, vents, other piping systems, or electrical conduit.
    • (x) Tiebacks shall be installed perpendicular to the face of the building or structure, or opposing angle tiebacks shall be installed. Single tiebacks installed at an angle are prohibited.
  • (4) Suspension scaffold outrigger beams shall be:
    • (i) Provided with stop bolts or shackles at both ends;
    • (ii) Securely fastened together with the flanges turned out when channel iron beams are used in place of I-beams;
    • (iii) Installed with all bearing supports perpendicu-lar to the beam center line;
    • (iv) Set and maintained with the web in a vertical position; and
    • (v) When an outrigger beam is used, the shackle or clevis with which the rope is attached to the outrigger beam shall be placed directly over the center line of the stirrup.
  • (5) Suspension scaffold support devices such as cornice hooks, roof hooks, roof irons, parapet clamps, or similar devices shall be:
    • (i) Made of steel, wrought iron, or materials of equivalent strength;
    • (ii) Supported by bearing blocks; and
    • (iii) Secured against movement by tiebacks installed at right angles to the face of the building or structure, or opposing angle tiebacks shall be installed and secured to a structurally sound point of anchorage on the building or structure. Sound points of anchorage include structural members, but do not include standpipes, vents, other piping systems, or electrical conduit.
    • (iv) Tiebacks shall be equivalent in strength to the hoisting rope.
  • (6) When winding drum hoists are used on a suspension scaffold, they shall contain not less than four wraps of the suspension rope at the lowest point of scaffold travel. When other types of hoists are used, the suspension ropes shall be long enough to allow the scaffold to be lowered to the level below without the rope end passing through the hoist, or the rope end shall be configured or pro-vided with means to prevent the end from passing through the hoist.
  • (7) The use of repaired wire rope as suspension rope is prohibited.
  • (8) Wire suspension ropes shall not be joined together except through the use of eye splice thimbles connected with shackles or coverplates and bolts.
  • (9) The load end of wire suspension ropes shall be equipped with proper size thimbles and secured by eyesplicing or equivalent means.
  • (10) Ropes shall be inspected for defects by a competent person prior to each workshift and after every occurrence which could affect a rope's integrity. Ropes shall be replaced if any of the following conditions exist:
    • (i) Any physical damage which impairs the function and strength of the rope.
    • (ii) Kinks that might impair the tracking or wrapping of rope around the drum(s) or sheave(s).
    • (iii) Six randomly distributed broken wires in one rope lay or three broken wires in one strand in one rope lay.
    • (iv) Abrasion, corrosion, scrubbing, flattening or peening causing loss of more than one-third of the original diameter of the outside wires.

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