- Standard Number:1910.24(c)
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 http://www.osha.gov.
May 8, 2000
Mr. M. Podlovsky, P.E.
Fluor Daniel Wright Ltd.
1075 W. Georgia St.
Vancouver, British Columbia, Canada V6E 4M7
Dear Mr. Podlovsky:
Thank you for your March 3, 2000 letter to the Occupational Safety and Health Administration's (OSHA's) [Directorate of Enforcement Programs (DEP)]. You have requested an interpretation of 29 CFR 1910.24(c), Fixed Industrial Stairs, Stair strength, in regards to the application of a 1000 lbs load on fixed industrial stairs. Your questions are restated below for clarity.
Question 1: What "strength to carry safely" level is expected of the stair as far as resistance to this load: Yield or allowable, i.e. to failure or to allowable stresses used for steel design?
Reply: The design of fixed stairways and their components must be based on their ultimate strength [yield stress (FY) or ultimate stress (FU)] and not on the allowable stresses as given in the Allowable Stress Design method of the American Institute of Steel Construction, Ninth Edition.
Question 2: Where should it [1000 lbs load] be applied: Stringers, Stair treads?
Reply: From a design standpoint, the specified design loads (e.g., normal live load and moving concentrated load of 1000 lbs) must be placed where the maximum stress is experienced by the individual structural components of the stair system.
Question 3: Is it a concentrated load or spread over the whole stair tread area?
Reply: 29 CFR 1910.24(c) states; "Fixed stairways shall be designed and constructed to carry a load of five times the normal live load anticipated but never of less strength than to carry safely a moving concentrated load of 1,000 pounds" [emphasis added]. Therefore, with respect to the design calculation, the normal live load is spread over the whole stair tread area and the moving concentrated load is considered to be a point load applied at a location on the stair system where the maximum stress would be experienced by the system (the 1000 lbs loading criteria is a minimum).
Thank you for your interest in occupational safety and health. We hope you find this information helpful. Please be aware that OSHA's enforcement guidance is subject to periodic review and clarification, amplification, and correction. Such guidance could also be affected by subsequent rulemaking. In the future, should you wish to verify that the guidance herein remains current, you may consult OSHA's website athttp://www.osha.gov. If you have any further questions, please feel free to contact the [Office of General Industry Enforcement] at 202-693-1850.
Richard E. Fairfax, Director
[Directorate of Enforcement Programs]