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 https://www.osha.gov.

April 16, 2002

Mr. Philip Torchio
Vice President
Williams Enterprises of Georgia, Inc.
1285 Hawthorne Avenue
P.O. Box 756
Smyrna, Georgia 30081

Re: Tank builders' scaffold; scaffold planking; §1926.451(b);

Dear Mr. Torchio:

This responds to your September 27, 2001 letter to the Occupational Safety and Health Administration (OSHA) in which you ask for a clarification of OSHA's construction scaffold standard. Your inquiry concerns a tank builders' scaffold, a 20-inch platform, full planking, an Appendix A safety line, and anchored workers wearing personal fall arrest systems. We apologize for the delay answering your letter.

As explained below, you do not have to install as many planks as will fit on your tank builders' scaffold irons beyond the 18-inch minimum width. Depending on the height of your work platforms and distance between their front edges and the tank shell, your workers will have to use conventional fall protection.

The scenario described in your letter indicates that your tank builders' scaffold uses typical shell-supported scaffold irons, has a two-plank-wide wood deck, and has a wire rope exterior guardrail. The outside of the vessel shell supporting your scaffold is not uniformly symmetrical and round. You do not describe the size or nature of the openings between the front edge of the scaffold work platform planks and the tank shell, nor do you describe the maximum width of these openings.

Your letter describes a disagreement over the scaffolding issues between your company and the general contractor. If your issue is the accuracy of the general contractor's reading of the OSHA scaffold standard, we can answer your inquiry. On the other hand, if your general contractor is imposing additional requirements, even if based on a misreading of OSHA standards, then that is not one that OSHA can address. In such circumstances, the imposition of requirements beyond those required by OSHA is a contract issue between the parties, which we cannot address.

From you letter it appears (and for the purposes of this answer we assume) that your general contractor is asserting theirs is the correct reading of OSHA's scaffold standard, Part 1926 Subpart L (§§1926.450-1926.454 and appendices), in particular §1926.451(b)(1).

We paraphrase your questions as follows:


Question (1) Must my tank builders' scaffold platforms be fully planked?

At first glance, 29 CFR 1926.451(b) Scaffold platform construction, appears to address your issue about fully decked or planked scaffold platforms. It appears to read as a checklist of requirements for all supported scaffolds. However, not all the §1926.451(b) requirements apply to tank builders' scaffolds.

Section 1926.451(b)(1) requires that:

Each platform on all working levels of scaffolds shall be fully planked or decked between the front uprights and the guardrail supports as follows:

(i) Each platform unit … shall be installed so that the space between adjacent units and the space between the platform and the uprights is no more than 1 inch…. [Emphasis added.]

This language does not apply to your tank builders' scaffold - it applies to scaffolds with front uprights. Based on your description, your scaffold uses the tank shell as the support for the bracket or scaffold irons and is not erected with front uprights. Because your tank builders' scaffold lacks front uprights, §1926.451(b)(1) does not apply.

Section 1926.451(b)(2) contains several requirements that do apply to your scenario. Your 20- inch-wide work platform exceeds the minimum width required by §1926.451(b)(2), which reads as follows:

Except as provided in paragraphs (b)(2)(i) and (b)(2)(ii) of this section, each scaffold platform and walkway shall be at least 18 inches (46 cm) wide.

The (b)(2)(i) exception is inapplicable to your situation. Under (b)(2)(ii), if the employer demonstrates the area is too narrow for 18-inch platforms, the platform must be made as wide as feasible and guard rails and/or fall protection be provided. Paragraph (b)(2)(ii) reads as follows:

Where scaffolds must be used in areas that the employer can demonstrate are so narrow that platforms and walkways cannot be at least 18 inches (46 cm) wide, such platforms shall be as wide as feasible, and employees on those platforms and walkways shall be protected from fall hazards by the use of guardrails and/or personal fall arrest systems.

From the description of your setup, you exceed this requirement or have no areas so narrow you cannot install a platform that is at least 18 inches wide.

Section 1926.451(b)(3) addresses the hazard of open space between the front edge of the scaffold platform and the tank shell. It requires:

Except as provided in paragraphs (b)(3)(i) and (ii) of this section, the front edge of all platforms shall not be more than 14 inches (36 cm) from the face of the work, unless guardrails systems are erected along the front edge and/or personal fall arrest systems are used in accordance with paragraph (g) of this section [§1926.451] to protect employees from falling.

According to your letter, you elected the personal fall arrest system alternative and require all youremployees to be tied off. It also seems you investigated Non-mandatory Appendix A, paragraph (z), and took advantage of the safety wire suggested for the space between the work platform front edge and the tank shell. Your 20-inch-wide platform suggests you are using rough-cut lumber, another suggestion contained in paragraph (z). Please note that the exceptions, paragraphs (b)(3)(i) and (ii), do not apply to your tank builders' scaffold scenario.

Based on the information submitted, it appears that you have exceeded these requirements by using a wider platform (20 vs. 18 inches) in conjunction with using personal fall arrest systems and the Non-mandatory Appendix A paragraph (z) safety wire line.

Question (2): Must my tank builders' scaffold platforms be fully planked during erection and dismantling?


As explained above, since §1926.451(b)(1) applies only to scaffolds with front uprights, this section and its subordinate paragraphs do not apply to your tank builders' scaffold scenario.

Unlike §1926.451(b)(1), there is no exception in the standard to the §1926.451(b)(2) requirement specific to platforms used solely for erecting or dismantling. However, where an employer shows that full compliance is infeasible, it will not be cited as long as it has complied to the extent feasible.

If you need additional information, please do not hesitate to contact us by fax at: U.S. Department of Labor, OSHA, Directorate of Construction, [Office of Construction Standards and Compliance 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.


Russell B. Swanson, Director
Directorate of Construction