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.

January 23, 2003

Mr. Justin Breithaupt
Non-Stop Scaffolding, Inc.
1314 Hoadley Street
Shreveport, LA 71104

Re: Whether Non-Stop base tower and extension frames meet scaffold access requirements, §1926.451(e)(6) and (7)

Dear Mr. Breithaupt:

This is in response to your May 30, 2002 fax regarding the issue of whether base tower and extension frames used for access on Non-Stop scaffolding meets OSHA requirements. You had originally asked this question by letter dated June 5, 2001. We responded in a
March 14, 2002 letter in which we indicated that the ladder frames do not comply with §1926.451(e)(6)(ii), (e)(6)(vi), and (e)(7). We apologize for the delay in responding.

In your May 30 letter, you submitted various sketches (Exhibits A-D). These materials also included Western Falsework Engineering's May 22, 2002 letter to you disagreeing with our March 14, 2002, conclusions. In addition to your submissions we have studied the Non-Stop Scaffolding Assembly and Use Manual. These materials have not changed our interpretation of the requirements of the standard as they apply to Non-Stop base tower and extension frames.

In our March 14 letter, we stated that Non-Stop base tower and extension frames fail to meet OSHA requirements due to the inadequate tread width of their horizontal braces, the lack of vertical alignment of footholds and the existence of non-uniform vertical steps (requiring steps greater than 16¾ inches). Specifically, we stated:

As required by §1926.451(e)(6)(ii), Non-Stop provides more than 8 inches of tread on many of its horizontal braces. However, it does not provide a minimum rung length of 8 inches on many others. The configuration of the trusses appears to reduce the distance below 8 inches (i.e., the angle between the horizontal and diagonal legs effectively reduces the useable rung width to less than 8 inches). The section's joint truss and bolt create tread widths less than 6 inches to each side rail. In addition, the truss shapes and nut/bolt-head obstructions violate §1926.451(e)(7), which requires vertical step/rung alignment.

Lastly, while it is also true that the standard allows irregular vertical rung spacing at end frame joints, the Non-Stop tower configuration creates a minimum vertical step of 36 inches between uniform horizontal braces. 36 inches exceeds the OSHA requirement. Section 1926.451(e)(6)(vi) permits non-uniform spacing "provided the resulting spacing does not exceed 16¾ inches."

The additional materials fail to demonstrate that our conclusions were erroneous. We note your statement that "contrary to your letter of March 14, 2002, page 3, there are no instances where the space between horizontal rungs ("braces") is 36 inches. Except for the first step, the maximum step is 9 inches."

The maximum distance allowed between rungs is measured by the distance between rungs that comply with the requirements of the standard. There are numerous examples where you would have to step more than 16¾ inches to reach the next 8-inch tread (for example, in the picture below, the arrows indicate places where rungs have less than 8-inch treads).


Picture indicates by arrows places where rungs have less than 8-inch treads

An additional requirement that affects irregular tread spacing is the requirement in §1926.451(e)(7) for vertical tread alignment. Treads that are not aligned with each other vertically force steps greater than the 16¾ inch maximum step prescribed by OSHA. As you can see on the Non-Stop parts diagram below there are several instances where a complying tread is not aligned with the tread above or below it (arrows indicate where diagonal bracing forces tread misalignment and circles indicate where X-braces and their mounting pins force misalignment.). In addition to pins, X and other braces, the nuts and bolts that hold frame sections together force tread misalignment at each frame section joint (squares indicate these nuts and bolts.)


Picture indicates by arrows places where nuts and bolts that hold frame sections together force tread misalignment at each frame section joint

We disagree with Western Falsework Engineering's opinion that the failure to meet the standard's requirements should be considered de minimis. The specification requirements in the standard were designed to ensure that workers would be able to consistently place their feet when ascending and descending (especially where workers do not see the next step, as is typical, especially during a descent). The requirements achieve this by ensuring a high degree of similarity in position and configuration of the stepping areas and sufficient room to place your foot while in motion. Failure to meet these minimum requirements places workers at risk of misstepping and falling.

You also requested a permanent variance from §1926.451(e)(6)(ii), which requires rungs to be at least 8 inches long. We have forwarded your variance request to the Office of Technical Programs and Coordination Activities (202-693-2110).

If you need additional information, please contact us by fax (202-693-1689) at: U.S. Department of Labor, OSHA, Office of Construction Standards and Guidance. You can also contact us by mail at U.S. Department of Labor, OSHA, Office of Construction Standards and Guidance, 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