April 08, 2005

Mr. Douglas A. Holman
1816 River Bend Road
Sevierville, TN 37876

Re: Whether scaffold components may be loaded in excess of minimum load ratings specified in 29 CFR Part 1926 Subpart L; whether a safety factor must be added to such load ratings; §1926.451(g)(4) (vii) and 1926.451(g)(4)(ix) and 1926.451(h)(4)(i); Non-Mandatory Appendix A

Dear Mr. Holman:

You have submitted nine letters to the Occupational Safety and Health Administration (OSHA) containing a number of questions on the construction scaffold standard (29 CFR Part 1926 Subpart L).¹ We are responding in a series of separate letters in response; this is the second in that series.

We have paraphrased your questions regarding loading scaffold components and the application of safety factors as follows:

Question (a): My questions relate to the scaffold requirements in §1926.451(g)(4)(vii) and 1926.451(g)(4)(ix) and 1926.451(h)(4)(i), as well as those referenced in the charts in Section 1(b)(i) and (c) of Part 1926 Subpart L's Non-Mandatory Appendix A. Do these provisions set the maximum load that is permitted to be imposed?

Answer: General scaffold requirements, including those that you referenced related to capacity, fall protection and falling object protection, are included in §1926.451. Specifically, capacity requirements are in §1926.451(a)(1):

Except as provided in..., each scaffold and scaffold component shall be capable of supporting, without failure, its own weight and at least 4 times the maximum intended load applied or transmitted to it.

Section 1926.451(a)(6) states in part:

...Non-mandatory Appendix A to this subpart contains examples of criteria that will enable an employer to comply with paragraph (a) of this section.

Fall protection criteria are set forth in §1926.451(g)(4). Among other requirements, that provision provides:

* * * * *
(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.
* * * * *
(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 of 100 pound toprail capacity and a minimum 200 pound toprail capacity.
* * * * *

Finally, the falling object protection provision in §1926.451(h)(4)(i) that you refer to states:

When used, toeboards shall be capable of withstanding, without failure, a force of at least 50 pounds (220 n) applied in any downward or horizontal direction at any point along the toeboard...

Although these provisions do not address whether a load greater than these minimum strength requirements may be applied, §1926.451(f)(1) does address that question:

Scaffolds and scaffold components shall not be loaded in excess of their maximum intended loads or rated capacities, whichever is less.

A load greater than the applicable minimum strength requirement is permitted to be applied only to the extent the scaffold's (and scaffold component's) design strength exceeds the applicable requirement. In no case, is it permissible to load scaffolds and scaffold components in excess of their maximum intended loads or rated capacities, whichever are less.

Question (b): Is there a safety factor that is required to be applied with respect to meeting these requirements for guardrails, toeboards, or other components on scaffolds?

With respect to §1926.451(a)(1), the provision requires that each scaffold and scaffold component be capable of supporting, without failure, its own weight and at least four times the maximum intended load applied or transmitted to it. To the extent you are asking if a scaffold/scaffold component must not only meet this 4:1 ratio but also have an additional margin of strength, the answer is no.

Similarly, with respect to the other provisions you mention, to the extent you are asking if a scaffold/scaffold component must not just meet the specified strength criteria but, in fact, exceed it, the answer is also, no.²

We note that, as a practical matter, the qualified person³ designing the scaffold will typically include some additional margin of strength in the design in order to ensure that, in fact, the scaffold and scaffold components meet the criteria in the standard. However, with regard to what is actually required by the standard, as long as the scaffold meets the minimum criteria, no additional strength is required.

If you need additional information, please contact us by fax at: U.S. Department of Labor, OSHA, Directorate of Construction, Office of Construction Standards and Guidance, fax # 202-693-1689. You can also contact us by mail at the above office, Room N3468, 200 Constitution Avenue, N.W., Washington, D.C. 20210, although there will be a delay in our receiving correspondence by mail.

Sincerely,


Russell B. Swanson, Director
Directorate of Construction

¹ When we originally received these questions from you in April 2003, it was unclear to us if you were requesting a response to each or if they were submitted only to call our attention to these issues in the event that OSHA were to do further rulemaking on the standard. We attempted to resolve that with you, but we were unable to obtain a response; consequently, our office closed the file. After your communications with my staff on January 13, 2005, we understand now that you are requesting a response to each question. We apologize for the misunderstanding and resulting delay in providing this response. [ back to text ]

² The charts that you reference in Appendix A provide maximum intended load criteria for specific lumber (based upon certain described variables). This information is furnished solely for the convenience of the employer so that such information can be incorporated into a scaffold's total design that must comply with the minimum 4:1 load bearing requirements. [ back to text ]

³ Under §1926.451(a)(6), a qualified person is required to design the scaffold. [ back to text ]