Associations Voice Concern Over Current Fire Testing of Membrane Roof Systems

Feb. 7, 2006
Long-term research evokes questions about the fire resistance of aged and new membrane roof assemblies

During the past several years, the Midwest Roofing Contractors Association (MRCA) and the National Roofing Contractors Association (NRCA) have been working jointly on a long-term research program of fire testing aged and new membrane roof assemblies. This research has revealed some findings that should be of concern to roofing professionals including contractors, designers, manufacturers, distributors, building owners and operators, testing agencies, and code authorities.

A report released in January 2006 provides a brief background and overview of the MRCA/NRCA research program and makes specific recommendations for action which MRCA and NRCA feel are appropriate.

The research began in 1996 as a continuation of the MRCA/NRCA field performance of polymer-modified bitumen systems study, and was originally intended to provide roofing contractors with useful information regarding the elapsed time projected for recoating membrane roof systems to maintain fire-resistance ratings. Unfortunately, the results of this research objective are inconclusive because of the variability in results found using the ASTM E108 spread-of-flame method. The variability discovered using this test method is so pronounced that, at times, recognized Class-A listings and approvals of newly installed, mechanically attached EPDM and TPO membrane systems could not be duplicated under controlled laboratory conditions.

As a result of the findings from this research, MRCA and NRCA are concerned the spread-of-flame portion of ASTM E108 may not accurately represent the exterior fire performances of low-slope membrane roof systems, particularly for mechanically attached, single-ply membrane roof systems. This same concern also applies to roof systems tested using UL 790, “standard for tests for fire resistance of roof coverings,” and NFPA 256, “standard method of fire tests for roof coverings,” which are largely similar to ASTM E108. Because one or more of these test methods is included in the model building codes and most local and state codes as the basis for determining roof systems’ compliance with exterior fire-exposure requirements, the issue of code compliance for these systems is also of concern.

The results of this research and associated concerns already have been shared with ASTM, UL, FM, and other fire-testing laboratories involved in this research, and the individual roof system manufacturers whose products were involved in this testing.

This information has been excerpted from Fire Testing of Membrane Roof Systems, a special report issued by the Midwest Roofing Contractors Association and the National Roofing Contractors Association. To read the associations’ recommendations and complete report, visit (

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