April 30, 2010

Letter #[20090718-9206]

Re: (1)Whether #9 wire may be used to secure the toprails and the midrails on tubular scaffolding, and (2) A permissible method for setting transitional wood planks before changing direction on tubular scaffolding utilizing aluminum hook-on planks.

Question #1: Does the OSHA scaffold standard for construction (Part 1926 Subpart L) permit the use of #9 wire to secure the toprails and the midrails on tubular scaffolding?

Answer #1:

Title 29 CFR 1926.451 (g)(4) provides the requirements for guardrail systems. Some of the relevant provisions state:

(vii) Each toprail or equivalent member of a guardrail system shall be capable of withstanding, without failure, a force applied in any downward or horizontal direction at any point along its top edge of at least 100 pounds (445 n) for guardrail systems installed on single-point adjustable suspension scaffolds or two-point adjustable suspension scaffolds, and at least 200 pounds (890 n) for guardrail systems installed on all other scaffolds.

(viii) When the loads specified in paragraph (g)(4)(vii) of this section are applied in a downward direction, the top edge shall not drop below the height above the platform surface that is prescribed in paragraph (g)(4)(ii) of this section.

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(ix) Midrails, screens, mesh, intermediate vertical members, solid panels, and equivalent structural members of a guardrail system shall be capable of withstanding, without failure, a force applied in any downward or horizontal direction at any point along the midrail or other member of at least 75 pounds (333 n) for guardrail systems with a minimum 100 pound toprail capacity, and at least 150 pounds (666 n) for guardrail systems with a minimum 200 pound toprail capacity.

Employers must ensure that scaffolds are designed, erected and maintained in accordance with the applicable provisions of Subpart L of Part 1926. Section 1926.45 l(g)(4), which provides requirements for guardrail systems, does not mandate a particular material to be used for securing the toprails and the midrails on tubular scaffolding.

If the #9 wire results in a guardrail system that meets the capacity and other requirements in Subpart L, then #9 wire is permissible to secure the toprails and midraiIs on tubular scaffolding. See paragraph 1(d) of Appendix A to Subpart L for additional guidance.

Question #2: What is a permissible method under Section 1926.451(b)(8) for setting the transitional wood planks before changing direction on tubular scaffolding utilizing aluminum hook-on planks?

Answer #2:

Title 29 CFR 1926.451(b) provides the requirements for scaffold platform construction. Subsection 8 addresses changing the direction of the platform and states:

(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.

When turning a corner at an angle other than a right angle and using transitional wood planks and aluminum hook-on planks, section 1926.451(b)(8) requires that the wood planks, which rest on a bearer at an angle other than a right angle, be laid first and the aluminum hook-on planks, which rest at right angles over the same bearer, be laid second, on top of the wood planks. This method is not desirable because the hook, which rests on top of the flat wood plank, creates a tripping hazard.

To avoid creating a tripping hazard, unless the aluminum hook-on plank manufacturer makes hook-on planks at an angle other than a right angle, a contractor may start the second section flush with the outside of the first section. This method eliminates the need to use planks at other than a right angle as described in 1926.45l(b)(8), and thus removes the tripping hazard because no layering of planks is necessary to turn the corner.

Sincerely,



Bill Parsons, Acting Director
Directorate of Construction