Plywood sheeting in excavation shoring systems

February 19, 1993

Mr. George S. Kennedy
Director of Safety
National Utility Contractors Association
[Recipient address omitted]
Dear Mr. Kennedy:

This is in response to your January 5 letter requesting an interpretation of an Occupational Safety and Health Administration standard addressing excavations.

With regard to whether two layers of 3/4-inch thick plywood can be used to hold back raveling when used with an aluminum hydraulic waler system, please be advised that where an employer chooses to design a protective system in accordance with 29 CFR 1926.652(c)(1), option (1), plywood cannot be used as a substitute for any primary load carrying structural member such as the timber uprights or aluminum rails as called for in Tables D-1.1 through D-1.4. However, plywood can be used to contain raveled soil and to transfer the loads imposed by this soil to the load carrying members. Please note that the plywood illustrated in the sketch on page 2 of your letter appears to be a primary load carrying member instead of being a member to only prevent raveling of soil as intended in the OSHA regulations (see Note (g)(7) of Appendix D to Subpart P).

Regarding the general application of plywood as a sheeting member for shoring and support systems in trenches and excavations, please see paragraph 1926.652(c)(3) or (4), Option (3) or (4). An employer who elects to use either option must meet only the requirements of that subsection and is not bound by the requirements in the appendices of 1926.652. Registered professional engineers who develop tabulated data for use by employers under Option (3) or (4) often will include plywood sheeting as a component of support systems.

If we can be of any further assistance please contact me or Mr. Dale R. Cavanaugh of my staff at (202)219-8136.

Sincerely,
Roy F. Gurnham, P.E., Esq. Director
Office of Construction and Maritime
Compliance Assistance

[Requester letter reproduced on OSHA page; omitted here.]