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Standard Interpretations - Table of Contents
• Standard Number: 1926.451; 1926.451(b)(1)


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.

Letter #20070906-7946

Re: Fully Planked and Decked Scaffold

Question: When may the space between scaffold planks or between scaffold planks and uprights exceed one inch in width?

Answer: The relevant standard, 29 CFR §1926.451(b)(1)(i), states:

Each platform unit (e.g., scaffold plank, fabricated plank, fabricated deck, or fabricated platform) 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 (2.5 cm) wide, except where the employer can demonstrate that a wider space is necessary (for example, to fit around uprights when side brackets are used to extend the width of the platform).  (Emphasis added).

In addition, 29 CFR §1926.451(b)(1)(ii) states:

Where the employer makes the demonstration provided for in paragraph (b)(1)(i) of this section, the platform shall be planked or decked as fully as possible and the remaining open space between the platform and the uprights shall not exceed 9 ½ inches (24.1 cm).  (Emphasis added).

The standard requires that the space between the scaffold planks or between scaffold planks and uprights be no more than one inch wide unless the employer can demonstrate that a wider space is necessary.  However, the platform must still be planked or decked as fully as possible.  As explained in the rule and preamble, one situation where the exception would apply is when the platform must fit around uprights when side brackets are used to extend the width of the platform.  As further clarification, the preamble to the final rule, at 61 FR 46039, explains why the exception was added:

In order to comply with the existing rule, some employers have modified the last plank (notched slanted, or cut it to size).  This can lead to a significant reduction in plank strength, and possibly cause tipping of the plank (sideways) if eccentrically loaded.  Therefore, to deal with this problem, proposed and final rule paragraph (b)(1) have modified the corresponding requirement of the existing standard by requiring the span between uprights to be planked or decked as fully as possible, but allowing up to 9 ½ inches between the planking or decking and the guardrail supports.  As explained above, 9 ½ inches is the maximum allowable open space.

The exception to the one inch limitation in width was added to prevent employers from modifying the planks used to construct the platform because such modification could cause a tipping hazard.  Therefore, platforms should be constructed in such a way that they are planked as fully as possible without modifying any of the planks.  In other words, the space between scaffold planks or between scaffold planks and uprights must be as narrow as possible and may only exceed one inch in width if the space cannot be reduced without modifying any of the planks used to construct the platform.  In no circumstances, however, may the width between scaffold planks or between scaffold planks and uprights exceed 9 ½ inches.  If the employer can demonstrate that complying with the one inch limitation in width would require modifying any of the planks used to construct the platform, the exception would apply.

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,



Richard E. Fairfax, Acting Director
Directorate of Construction


Standard Interpretations - Table of Contents

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