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Standard Interpretations - Table of Contents
• Standard Number: 1926.451; 1926.451(g)(1); 1926.451(g)(3)(iii); 1926.552; 1926.552(c)(7)

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

March 31, 2010

Letter #20081021-8670:

Re: Single-point suspension scaffold safety.

Question 1: What is a "structural member" of a scaffold?

Answer 1: A "structural member" of a scaffold is any part of the walking/working surface of the scaffold, as well as the supports for the walking/working surface, including but not limited to uprights, suspension ropes, bracing, outrigger beams, access ladders, etc.

Question 2: What are the structural (performance) requirements for the following types of falling object protection mentioned in §1926.451(h)(1): canopy structure, debris net, and catch platform? Would this requirement be satisfied by following the requirements of §1926.552(c)(7)?

Answer 2: OSHA does not set forth specific performance requirements in the scaffolding standard for falling object protection systems. However, in order to fulfill the requirements of the standard - that is, to abate the struck-by hazard presented by potential falling objects, the falling object protection systems would need to be sufficiently strong to withstand the potential impact of the objects above the scaffold.

Section 1926.451(h)(1) requires that:

In addition to wearing hardhats each employee on a scaffold shall be provided with additional protection from falling hand tools, debris, and other small objects through the installation of toeboards, screens, or guardrail systems, or through the erection of debris nets, catch platforms, or canopy structures that contain or deflect the falling objects. When the falling objects are too large, heavy or massive to be contained or deflected by any of the above-listed measures, the employer shall place such potential falling objects away from the edge of the surface from which they could fall and shall secure those materials as necessary to prevent their falling.

Thus, whichever protective method is chosen, it must be sufficiently strong to deflect or contain the potential falling objects. If none of the methods can achieve this, the hazard must be abated by removing the objects from the area from which they might fall.

Section 1926.552(c)(7) addresses the requirements for the covering that must be provided for the top of every personnel hoist. This requirement does not necessarily satisfy the requirement of §1926.451(h)(1), because personnel hoists are not designed for the same activities as scaffolds, and would therefore not necessarily be subject to the same types of falling object hazards. Because employees on a scaffold may be engaged in work that exposes workers to falling objects of a wide variety of shapes and sizes, the appropriate falling object protection needs to be determined on a case-by-case basis.

Question 3: Would a breakaway canopy satisfy the requirements of §1926.451(h)(1)? If so, what are the performance standards for a breakaway canopy?

Answer 3: A breakaway canopy is not prohibited under §1926.451(h)(1). Such a canopy must be designed to prevent injury to the worker from falling objects, or from the canopy itself.

Question 4: Is it possible to use a canopy over a single-point suspension scaffold and still fulfill the requirements of §1926.451(g)(3)?

Answer 4: Yes. Workers on single-point suspension scaffolds must be provided fall protection according to §1926.451(g)(1)(ii), which states: "Each employee on a single-point or two-point adjustable suspension scaffold shall be protected by both a personal fall arrest system and guardrail system". That fall arrest system must meet the requirements set forth in §1926.451(g)(3), which specifically prohibits the use of vertical lifelines in conjunction with overhead protection such as a canopy:

In addition to meeting the requirements of §1926.502(d), personal fall arrest systems used on scaffolds shall be attached by lanyard to a vertical lifeline, horizontal lifeline, or scaffold structural member. Vertical lifelines shall not be used when overhead components, such as overhead protection or additional platform levels, are part of a single-point or two-point adjustable suspension scaffold.

A canopy is an example of an "overhead component, such as overhead protection" that cannot be used in conjunction with a vertical lifeline. However, this section allows the lanyard of a personal fall arrest system to be attached to a horizontal lifeline or scaffold structural member. This arrangement is covered by §1926.451(g)(3)(iii):

When lanyards are connected to horizontal lifelines or structural members on a single-point or two-point adjustable suspension scaffold, the scaffold shall be equipped with additional independent support lines and automatic locking devices capable of stopping the fall of the scaffold in the event one or both of the suspension ropes fail. The independent support lines shall be equal in number and strength to the suspension ropes.

Thus, where an employer has chosen to erect a canopy over a single-point suspension scaffold, personal fall arrest systems must be used, and must be attached to either a horizontal lifeline or a structural member of the scaffold. In such situations, the scaffold must be equipped with independent support lines and automatic locking devices that will prevent the scaffold from falling should the suspension rope break.

Question 5: Are the independent support line(s) required by §1926.451(g)(3)(iii) and §1926.451(h)(3)(ii) the same?

Answer 5: Yes. If independent support lines are required under §1926.451(g)(3)(iii) (because a personal fall arrest lanyard is connected to a horizontal lifeline or scaffold structural member), and are also required under §1926.451(h)(3)(ii) (because a canopy has been installed over a suspension scaffold), the same independent support line(s) may be used to fulfill the requirements of both standards.

Question 6: Is the automatic locking device required by §1926.451(g)(3)(iii) the same as the "braking device or locking pawl which engages automatically" required by §1926.451(d)(16)?

Answer 6: No. The automatic locking device required by §1926.451(g)(3)(iii), quoted above, is attached to the independent support line, and is activated if the main suspension rope breaks. Section 1926.451(d)(16) states:

In addition to the normal operating brake, suspension scaffold power-operated hoists and manually operated hoists shall have a braking device or locking pawl which engages automatically when a hoist makes either of the following uncontrolled movements: an instantaneous change in momentum or an accelerated overspeed.

This "braking device or locking pawl" must be present regardless of whether independent support ropes are used. So a suspension scaffold that is attached to an independent support rope would have two separate automatic braking devices - one attached to the main suspension rope, the other attached to the independent support line.

Question 7: How much of a single-point suspension scaffold's working area must be covered by a canopy or similar structure in order to satisfy the requirements of §1926.451(h)(1)?

Answer 7: The falling object protection structure must be sufficient to protect the worker from falling object hazards. Note that the structure needs to be constructed and installed so that it does not create another hazard, e.g. by deflecting falling objects onto one end of the scaffold, potentially causing fall hazards through instability and/or breakage of the suspension rope.

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.


Bill Parsons, Acting Director
Directorate of Construction

Standard Interpretations - Table of Contents

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