Archive Notice - OSHA Archive

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at

August 11, 1987

                    Regional Administrator

FROM:               LEO CAREY, Director 
                    Directorate of Field Operations

SUBJECT:            Interpretation and Applicability of the requirements of
                    29 CFR 1926.450(a)(4) and (a)(5) to access ladder for 

A portable metal ladder meeting the requirements of 29 CFR 1926.450(a)(4) could be adequately attached to the outside of a tubular metal scaffold to provide safe access and egress to a work platform located 100 feet above the ground at the present time. The ladder would have to be positioned so that its use will not have the tendency to tip the scaffold. Cages, rest platforms or ladder safety device would not be required for employees ascending or descending the ladder. The enforcement of 29 1926.450(a)(5) would be inappropriate for a metal tubular scaffold.

With regard to other types of ladders, 29 CFR 1926.451(a)(13) in our general requirements for scaffolds requires only that an access ladder or equivalent safe access shall be provided. In view of the various rung spacings of ladder end scaffolds, which have been designed and manufactured over the past 30 years specifically to provide safe access to scaffolds, 29 CFR 1926.451(a)(13) should be liberally interpreted to permit the use of those ladder systems (both portable ladders and ladders built into the scaffold frame) which have a maximum rung spacing between rungs of 16-1/2 inches. Non uniform rung spacing caused by joining end frames together is allowed provided the resulting spacing does not exceed 16-1/2 inches. In no case would the requirements of 29 CFR 1926.450(a)(5) for fixed ladders apply in this situation.

On November 25, 1986 the Occupational Safety and Health Administration (OSHA) proposed to revise the Construction Industry Safety Standards addressing scaffolds. The proposal when finalized, hopefully, later this year will probably require hook-on and attachable ladders to be provided with rest platforms at 20 feet maximum vertical intervals for attached ladders. In addition hook-on and attachable ladders will probably re required to be specifically designed for use with manufactured types of scaffolds.