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.

August 7, 1998

Mr. Kenneth D. Gould
Senior Counsel, Regulatory Law
Owens Corning World Headquarters
One Owens Corning Parkway
Toledo, Ohio 43659

Dear Mr. Gould:

In a letter dated December 16, 1996, you requested that the Occupational Safety and Health Administration (OSHA) review the engineering, operational, and procedural documentation associated with the Elaminator 300 Insulation System ("the System"), which is manufactured and licensed for use by Owens Corning. You asked that OSHA determine whether the System provides fall protection that complies with the requirements of 29 CFR 1926.500-.502, or is an alternate form of fall protection that is suitable for a variance application. In response to an OSHA request, you provided additional information about the System on July 15, 1997, and, during subsequent months, you tried to arrange for the OSHA staff involved in this project to observe the System in operation. When no job sites had become available for observation by late January of this year, you requested that OSHA make a determination without observing the System in operation. However, you did provide OSHA with a video of the System in use. Our determination is based on a review of all of the materials and information submitted.

The System
The System consists of a winch-operated, metal platform, 10 feet long and 30 inches wide. The platform rides on guide rollers, which roll on the roof purlins of a steel building. It is installed at one end of the roof and travels along the purlins powered by a manually-operated winch. The winch is mounted on the platform and pulls a cable attached to the opposite end of the roof. The front side of the platform, which has guardrails, faces the direction of travel. The ends of the platform also have guardrails.

Also mounted on the platform are rolls of insulation. The beginning of the roll is attached to one end of the roof. As the platform advances across the roof, the insulation unwinds from the rolls, covering the top of the building. Alternatively, strips of insulation can be installed manually across the purlins.

Adjacent to the back side -- the trailing side -- of the platform, alongside its floor, large metal plates ("cantilever plates") are attached. These cantilever plates, along with the platform floor, form a temporary, moving work surface. Immediately after rolling the insulation a set distance, a metal roofing panel is laid over the insulation and attached to the previously installed roofing panel. At this point, the cantilever plates are under the area where the roofing panel is being installed. The new roofing panel has not yet been secured to the purlins. The platform is then advanced a set distance again, which moves the cantilever plates out from under the attached (but not yet secured) roofing panel. The platform is advanced to the point where the trailing edge of the cantilever plates are in line with the leading edge of the new roofing panel. A worker then steps on the new roofing panel and attaches it to the purlins with fastening clips. This operation is repeated across the entire length of the roof.

The purpose of the cantilever plates is to provide fall protection to workers who may step on the insulation prior to laying a new panel. The platform and guardrails provide fall protection to the part of the building that has not yet been roofed. The System does not provide fall protection to the perimeter of the roofed area.

Types of work; applicable standards. This operation involves two types of work, each of which is covered by a different standard. Installing insulation on roofs (above six feet) is covered by Subpart M of 29 CFR Part 1926, including sections .500 to .502. The installation of metal decking on a steel warehouse-type building, however, is considered a steel-erection activity. Fall hazards for that activity are covered by 29 CFR 1926.105(a). 1

Fall hazards for insulation workers on the System platform. A fall hazard facing insulation workers standing on the System platform is falling from the platform. Workers are protected by the guardrails on the platform, which meet the fall-protection requirements of 29 CFR 1926.502, and provide members of the System crew on the platform fall protection with respect to the guarded sides. When the System is being installed or removed from the roof, fall protection must be provided under Subpart M of 29 CFR 1926. The employer must ensure that the guardrails, platform, and the remaining System components are assembled and disassembled, and that the System is installed and removed from the roof, according to the manufacturer's instructions.

A second fall hazard to which the insulation and metal decking crews are exposed involves the cantilever plates. The plates provide protection against interior falls between the System platform and the leading edge of the work area. When workers step onto a cantilever plate, they must not exceed the rated load capacity of the plate (300 lbs.); insulation workers must be provided with personal fall protection as specified by 29 CFR 1926.501, unless the trailing edge of the cantilever plate does not present a fall hazard (see the conditions specified on pages 4 and 5 of this letter).

When members of the insulation crew are on the cantilever plate, they also are exposed to a fall hazard at the perimeter of the cantilever plate (e.g., the edge of the roof). Perimeter fall hazards must be controlled as required in 29 CFR 1926.501. In addition, employees who are under the cantilever plate must be protected from objects that may fall through the gap at the trailing edge of the plate (see paragraph (b)(4)(iii) of 29 CFR 1926.501). 2

Fall hazards for the metal roofing crew. Metal roofing crews that are working on non-tiered structures are exposed to several fall hazards. The perimeter of the work area (typically the edge of the roof) presents a fall hazard that must be controlled. Paragraph (a) of 29 CFR 1926.105 requires that perimeter fall hazards be controlled using ladders, scaffolds, catch platforms, temporary floors, safety lines, or safety belts; safety nets must be used when other methods of fall protection are impractical. Warning lines cannot be used for this purpose.

Metal roofing crews working on non-tiered buildings also are exposed to interior fall hazards. In this operation, a fall hazard is present at the leading edge of the last metal roofing panel to be fastened securely to the purlins ("fastened roof panel"). The leading edge of the fastened roof panel faces the System platform. The insulation runs under the fastened roof panel, over the cantilever plates and up to the rollers on the platform. The next roof panel is then attached to the standing seam of the fastened roof panel. The two panels are attached by hooking the raised ridge on each panel together, forming a continuous, locked raised ridge over the entire length of the two panels.

While the new roof panel is being attached to the seam of the fastened roof panel, the cantilever plates are beneath the area that the new roof panel is going to cover. Having the cantilever plates in this position provides interior fall protection (for that roof opening) as long as the load capacity of the cantilever plates is not exceeded and any gap between the trailing edge of the cantilever plates and the fastened roof panel is six inches or less.

The new roof panel cannot be fastened to the purlin while the cantilever plates are beneath it because the insulation is sandwiched between the new panel and the cantilever plate. The worker, therefore, cannot compress the insulation sufficiently to get the panel down to the purlin while the cantilever plate is below the insulation. As a result, before the new roof panel can be fastened to the purlins, the System must be advanced, which removes the cantilever plates from beneath the attached (but unsecured) roof panel. If the new roof panel that is attached to the seam of the fastened roof panel (but has not yet been secured to the purlin) can safely support the workers, there is no hazard of falling through the unfastened panel.

While working on non-tiered steel buildings at heights over 25 feet, workers engaged in metal roofing installation must be provided with the fall protection specified in paragraph (a) of 29 CFR 1926.105 with respect to all perimeter fall hazards, fall hazards in front of the System platform, and any interior fall hazards in the roofed portion of the work site. Fall protection in accordance with 29 CFR Subpart M must be provided to all employees installing insulation with respect to these hazards at heights over six feet. Furthermore, fall protection equipment must be provided and used in accordance with these standards to protect against fall hazards behind the System platform where the insulation and panels are being installed unless the following conditions are met:







  • The employer must ensure that the roofing panels can safely withstand the load of all workers standing on them while they are attached to the fastened panel but not yet secured to the purlins. Metal roof panels that hook together to form a secure, raised ridge across the entire length of the panels are often of this type.
  • The employer must ensure that the employees do not begin installing a new panel until the fastened panel has been permanently secured to the purlins.
  • After employees have attached the new panel to the fastened panel, but prior to fastening the new panel to the purlins, the employer must ensure that the attachment is secure and that the new panel will bear the weight of any employee who steps onto it without collapsing or separating from the fastened panel.
  • After employees have attached the new panel to the fastened panel and then placed the new panel on top of the insulation, the employer must ensure that the trailing edge of the cantilever plates are no more than six inches from the leading edge of the new panel.
  • 3


  • Before employees use the new panel to support themselves (i.e., prior to the new panel having been fastened to the purlins), the employer must ensure that:


    • All conditions specified above have been met.
    • No more than one employee is located on each length of the new panel that is facing a single cantilever plate (i.e., on the portion of a panel spanning two purlins).
    • 4


    • The cantilever plates are not occupied by other personnel, material, or equipment.
  • The employer must ensure that:


    • No more than one person is on a single cantilever plate during any part of the roofing operation.
    • A cantilever plate will not be used to support more than its rated load of 300 lbs. at any time.

Where these conditions are met, employees would not be exposed to interior fall hazards in the area behind the System platform where the panels and insulation are being installed. Therefore, as long as these conditions are met, a variance is not required with respect to fall protection requirements applicable to that area.

OSHA is precluded from approving or endorsing products; therefore, this letter should not be construed as an approval or endorsement of the Elaminator 300 Insulation System. If you have any questions or comments regarding this letter, or if you need further assistance in this matter, please contact Ms. Jennifer Silk, Director of the Office of Technical Programs and Coordination Activities, at (202) 219-7056, ext. 109.


Steven F. Witt
Directorate of Technical Support


FOOTNOTE (1) OSHA issued a letter of interpretation on July 10, 1995 in which it defined "steel erection activities"; included in this definition is the "[installation of] metal floor or roof decking." This letter differentiated between fall protection for employees working on "tiered" and "non-tiered" buildings at heights in excess of 25 feet. Steel erectors working on tiered buildings are protected by OSHA's Steel Erection standard (29 CFR 1926, Subpart R) with respect to interior fall hazards; when they work on non-tiered buildings, they are protected by paragraph (a) of 29 CFR 1926.105. Consequently, when employees install metal roofing panels (roof decking) on non-tiered warehouses (the typical situation in which the System is used), the employees are engaged in steel erection activities and protected by paragraph (a) of 29 CFR 1926.105. (Back to the Letter)


FOOTNOTE (2) Paragraph (b)(4)(iii) of 29 CFR 1926.501 is performance-based, so it is possible that the insulation spanning the gap could provide the required protection under some circumstances. (Back to the Letter)


FOOTNOTE (3) The employer is responsible for ensuring that this distance does not exceed six inches. The employer must exercise a high degree of diligence in operating the System so that this distance is not exceeded. In this regard, when two or more Systems are installed and operated in tandem, the employer must ensure that the winch operators align the multiple cantilever plates properly according the manufacturer's instructions. As noted above, the employer is responsible for providing the required fall protection. When relying on the System to provide that protection, the employer must ensure that the conditions on pages 4 and 5 of this letter are met - especially when their employees are exposed to the trailing edge of a cantilever plate or the leading edge of a roof panel. (Back to the Letter)


FOOTNOTE (4) This condition allows an employee to fall or jump safely, when necessary, onto the adjoining cantilever plate from the new panel without exceeding the rated load of the cantilever. (Back to the Letter)