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.

May 3, 2001

Joseph J. Novak
1399 Vischers Ferry Road
Clifton Park, New York 12065-6390

Re: 1926.501(b)(10); 1926.501(b)(13); STD 3-0.1A; personal fall arrest; safety monitors; warning lines.

[This document was edited on 12/5/12 to strike information that no longer reflects current OSHA policy referencing STD 3-0.1A.]

Dear Mr. Novak,

This is in response to your November 15, 2000 to the Occupational Safety and Health Administration (OSHA) in which you ask us to discuss fall protection requirements for workers engaged in "roof blocking." You ask if the requirements are different for carpenters as opposed to roofing contractors. We apologize for the delay in providing this response.


We understand "roof blocking" to be framing that is added around a hole (used for ventilation, heating, air conditioning, or other equipment) in a low sloped roof whichprovides support for equipment and aids in sealing the roof. The type of roof blocking we are referring to is not part of the support structure of the roof. This type of blocking may be installed in one of two ways.

In one method, blocking installation is done as an integral part of the installation of the weatherproofing material for the roof. The worker installs roofing material up to the roof hole, installs the blocking, and then continues installing the roofing material (including up and around the blocking). When done this way, since it is an integral part of installing the weatherproofing material, it is considered "roofing work."

Another method is to install the blocking separately -- before installation of the weatherproofing material begins. When done this way, it is not a part of roofing work.

Section 1926.501(b) defines "roofing work" as:

"the hoisting, storage, application, and removal of roofing materials and equipment, including related insulation, sheet metal and vapor barrier work, but not including the construction of the roof deck."

In general, OSHA's fall protection standard, §1926.501, requires that each employee on a walking/working surface (horizontal and vertical surface) with an unprotected side or edge which is 6 feet (1.8 m) or more above a lower level shall be protected from falling by the use of guardrail systems, safety net systems, or personal fall arrest systems. However, under §1926.501(b)(10), Roofing work on Low-sloped roofs, employers engaged in roofing work are permitted to use a combination of the additional methods listed below:

  1. warning line and guardrail system;
  2. warning line and safety net system;
  3. warning line and personal fall arrest system;
  4. warning line and safety monitoring system; or
  5. only a monitoring system on roofs 50-feet (15.25 m) or less in width in accordance with Appendix A of 1926 subpart M.

If the blocking is installed as an integral part of installing the weatherproofing material on a low-sloped roof, §1926.501(b)(10) applies. These methods are not available if the blocking is installed separately.

A carpentry contractor may be engaged in "roofing work"; if so, the methods in §1926.501(b)(10) would be available.

In answer to your question, the classification of this work as "roofing work" under §1926.501(b)(10) does not depend on whether it is done by a roofing contractor or a carpentry contractor. Whether roof blocking is considered to be roofing work depends instead on the installation method used, as described above. The activity and not the trade of the worker determines which requirements apply.

Please let us know if you need any further clarification on this subject and feel free to contact us again by writing to: Directorate of Construction-Office of Construction Standards and Compliance Assistance, Room 3468, 200 Constitution Avenue, N.W., Washington, D.C. 20210.


Russell B. Swanson
Director, Directorate of Construction