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• Standard Number: 1926.501(b)(13); 1926.502(k)

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

February 28, 2005




SUBJECT: Whether under [STD 03-00-001] an employee, in the absence of interior walls, is permitted to climb the lower chords of the roof trusses to brace them

This is in response to your e-mail submitted December 21, 2004. You ask whether under [STD 03-00-001 (formerly STD 3-0.1A)], an employee performing roofing work on a structure without interior walls may climb the lower chords of the roof trusses to brace them.

We have paraphrased your question as follows:

Question: An employer, engaged in residential construction, wishes to allow its employees to climb the lower chords of trusses of a structure with no interior walls to install bracing on the upper areas of the trusses. Is this permitted under STD 3-0.1A?

Answer: As described in detail below, climbing the lower chords of trusses is not part of the procedure described in STD 3-0.1A. Therefore [The] use of such a procedure would be permissible only if the employer met the applicable requirements of 29 CFR 1926.501(b)(13) for demonstrating the infeasibility of conventional fall protection and developing alternative procedures in a fall protection plan that met the requirements of §1926.502(k).

STD 3-0.1A provides alternative procedures to the conventional fall protection requirements in 29 CFR 1926.501(b)(13). These alternative procedures are only available for activities that meet a three-prong test: (1) the activities are done on a structure that falls within STD 3-0.1A's definition of "residential construction"; (2) they fall within one of the four activity Groups listed in the Directive; and (3) they comply with the additional requirements found in the applicable Group.

Specifically, Section IX of the Directive lists Group 1 activities as follows:


Section IX.B.1. sets forth additional requirements for the installation of roof trusses, a specific group (1) activity. As indicated above, this installation activity includes the bracing of roof trusses.

More specifically, Sections IX.B.1.b.(2) and (3) of the Directive set forth the procedures for the installation of trusses:

  • (2) Procedures for working on the top plate.
    • (a) Installing The First Two Trusses. The first two trusses/rafters must be set from ladders. The ladders must lean on side walls at points where the walls can support the load imposed by the ladder and worker. After the first two trusses/rafters have been set, a worker will climb a ladder onto the interior top plate to secure their peaks. [Emphasis added.]
    • (b) Remain On The Top Plate. Workers will remain on the top plate and use the previously stabilized trusses/rafters as support while the other trusses/rafters are erected.
  • (3) Procedures for working at the peak.
    • (a) Workers detaching trusses from cranes or securing trusses at the peak may be positioned at the peak of the trusses/rafters. * * * [Emphasis added.]
    • (b) Workers at the peak, in the web of trusses, or on top of the ridge beam shall work from a stable position. They must either sit on a ridge seat (or the equivalent or position themselves in previously stabilized trusses/rafters and lean into, and reach through, the trusses/rafters.
    • (c) Limited Fall Hazard Exposure.
      Workers must not remain on or in the peak/ridge any longer than necessary to complete the task safely.

Thus, STD 3-0.1A by its terms, with the noted limited exception for working at the peak,1 requires that the installation of trusses be accomplished while walking on the interior top plate. This position is in conformity with the Agency's recently stated position set forth in an interpretive memo to John Miles, Regional Administrator.2 As stated in that letter:

No mention is made in the Directive of walking on the trusses themselves for setting and bracing. Therefore, that practice is not permissible under the STD 3-0.1A procedures. [Emphasis added.]

You have indicated that in your scenario the structure does not contain any interior walls. As such, the employer cannot comply with STD 3-0.1A, which presumes the presence of interior walls.

As stated above, an activity must meet the requirements of a three-prong test to fall within the scope of the Directive. The third prong requires compliance with the procedures in the Directive. Since the requirements of the third prong cannot be met in your scenario, the described activity is not within the scope of STD 3-0.1A.3

Note, though, that §1926.501(b)(13) allows that employer to use alternative fall protection methods where it can demonstrate the infeasibility of conventional fall protection. The alternative procedures must be in a written, site-specific plan that complies with the criteria in §1926.502(k). So, the employer would be permitted to use this procedure if it were able to meet the requirements in §§1926.501(b)(13) and 1926.502(k).

If you need additional information, please contact us by fax or e-mail.

[This document was edited on 12/5/12 to strike information that no longer reflects current OSHA policy referencing STD 30-00-001.]

1 By its terms, this exception to working on interior top plates is limited to retrieving trusses from cranes and to securing trusses at their peak -- neither of which is applicable to your described activity. [ back to text ]

2 See Memo to John Miles, Regional Administrator (to the Attention of Roger F. Banaitis) dated November 30, 2004. [ back to text ]

3 In any case, as indicated, the Directive, even if it were to have been applicable, does not permit the practice of climbing on trusses except for the limited stated exceptions. [ back to text ]

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