December 6, 2013 [Reviewed and updated* April 24, 2020]

Steve Karasik, P.E.
Chief Engineer
PERI Formwork Systems, Inc.
Formwork and Shoring
7135 Dorsey Run Road
Elkridge, MD 21075

Dear Mr. Karasik:

Thank you for your letter to OSHA's Directorate of Construction dated November 7, 2011. We apologize for the delay in our reply. Your letter raises a specific question regarding OSHA's standards for scaffolds. This letter constitutes OSHA's interpretation of only the requirements discussed and may not be applicable to any question not delineated in your original correspondence.

Question: For scaffolds used in construction work, how is the weight of the scaffold taken into consideration in determining whether the 4 to 1 factor required by 29 CFR 1926.451(a)(1) is satisfied? How do the scaffolding requirements for general industry work differ from construction?

Response: Under section 1926.451(a)(1), each component of a scaffold system must be able to support its own weight (the weight of the component itself, in addition to the portion of the scaffold’s weight that is transmitted to that component), and at least 4 times the maximum intended load transmitted to that component. on that component, in addition to the weight of the component.

Section 1926.451(a)(1) provides:

Except as provided in paragraphs (a)(2), (a)(3), (a)(4), (a)(5), and (g) of this section, 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.

"Maximum intended load" is defined in 29 CFR 1926.450 as:

[T]he total load of all persons, equipment, tools, materials, transmitted loads, and other loads reasonably anticipated to be applied to a scaffold or scaffold component at any time.

When OSHA promulgated section 1926.451(a)(1), it clarified that the 4 to 1 factor corresponds to the total load applied to each scaffold component:

Paragraph (a)(1) requires that each scaffold and scaffold component be capable of supporting, without failure, its own weight and at least 4 times the maximum intended load applied or transmitted to it.... This provision is based on original standard § 1926.451(a)(7), which required that scaffolds and scaffold components "be capable of supporting without failure at least four times the maximum intended load."

The final rule clearly provides that the 4 to 1 factor for a component applies only to the load which is actually applied or transmitted to that component, and not to the total load placed on the scaffold.... The Agency intended that each component be adequate to meet the 4 to 1 factor, but only for the portion of the [maximum intended load] applied or transmitted to that component.

61 FR 46026, 46033 (Aug. 30, 1996). As this language makes clear, in applying section 1926.451(a)(1), each component of a scaffold must be able to support its own weight, plus 4 times the total maximum intended load on that component. For example, on a multi-level scaffold, each bottom leg must be able to support the scaffold weight transmitted to that component, including the component weight itself, its own weight and four times the portion of the maximum intended load reasonably anticipated to be imposed on that leg, which include the maximum intended load transmitted to that component and the maximum intended load directly applied to that component. (Note that the maximum intended load, as defined under section 1926.450, does not include the weight of the scaffold.) Part of the load imposed on a bottom leg will arise from the weight of the part of the scaffold that the bottom leg supports. Part of the maximum intended load will arise from the weight of persons, equipment, tools, and materials on the scaffold, and part will arise from other sources, such as wind.

In general industry, section 1910.27(a) requires that "Scaffolds used in general industry must meet the requirements in 29 CFR part 1926, subpart L (Scaffolds)."

In general industry, however, section 1910.28(a)(4) requires that "scaffolds and their components shall be capable of supporting without failure at least four times the maximum intended load." Under section 1910.21(f)(19), maximum intended load is defined as "the total load of all loads including the working load, the weight of the scaffold, and such other loads as may be reasonably anticipated."

Please note, however, that OSHA intends to resolve this inconsistency. In its proposed rule for Walking-Working Surfaces and Personal Protective Equipment (Fall Protection Systems), proposed §1910.27(a) states "Scaffolds, other than rope descent systems, used in general industry must meet the requirements for scaffolds in part 1926 (Safety and Health Regulations for Construction) of this chapter." See 75 Fed. Reg. 28862, 29139 (proposed May 24, 2010). The proposed rule would also change the definition of maximum intended load to align with the definition in Part 1926. 75 Fed. Reg. at 29131. In light of this proposal, OSHA advises that all scaffolds and scaffold components be manufactured to comply with the construction standard.

Thank you for your interest in occupational safety and health. We hope you find this information helpful. OSHA requirements are set by statute, standards, and regulations. Our letters of interpretation do not create new or additional requirements but rather explain these requirements and how they apply to particular circumstances. This letter constitutes OSHA's interpretation of the requirements discussed. From time to time, letters are affected when the Agency updates a standard, a legal decision impacts a standard, or changes in technology affect the interpretation. To assure that you are using the correct information and guidance, please consult OSHA's website at https://www.osha.gov. If you have further questions, please feel free to contact the Directorate of Construction at (202) 693-2020.

Sincerely,

James G. Maddux, Director

Directorate of Construction

* [The letter issued on 12/6/2013 had raised some confusion in the scaffold industry regarding what loadings were included in the maximum intended load and the application of 4 to 1 factor to the maximum intended load as required by 29 CFR 1926.451(a)(1). This letter has been modified to clarify these requirements for scaffolds as intended in the standard. This revision of the letter does not add any burdens or additional requirements that the standard did not intend, and reflects current OSHA regulations and policies.]