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NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.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

June 25, 1981

Mr. Marshall Klarfeld
Product Safety Engineer
Up-Right, Incorporated
1013 Pardee Street
Berkeley, California 94710

Dear Mr. Klarfeld:

This is in response to your letter of June 12, 1981, requesting an interpretation on the use of mobile scaffold towers.

29 CFR 1926.451(e)(1) requires when free standing mobile scaffold towers are use, the height shall not exceed four times the minimum base dimension. 29 CFR 1926.451(d)(3) requires scaffolds to be properly braces by cross bracing or diagonal braces, or both, for securing vertical members together laterally, and the cross braces shall be of such length as will automatically square and align vertical members so that the erected scaffold is always plumb, square, and rigid. 29 CFR 1926.451(e)(10) requires guardrails made of lumber, not less than 2 x 4 inches (or other material providing equivalent protection), approximately 42 inches high, with a midrail, of 1 x 6 inch lumber (or other material providing equivalent protection), and toeboards, shall be installed at all open sides and ends on all scaffolds more than 10 feet above the ground or floor. The photograph attached to your June 12th, letter indicates non compliance with the above standards for manually propelled mobile scaffolds.

The unit shown in your photograph should considered a single tower and comply with all of the applicable requirements in 29 CFR 1926.451(e).

It is not possible for this office to evaluate any lateral stability provided by the storage racks because of the lack of specific information on this matter. However, the tower unit as indicated in the photograph must be braced as required in 29 CFR 1926.451(d)(3).

If we may be of further assistance, please call or write.


John K. Barto Chief,
Division of Occupational Safety Programming