NRCA is concerned with fire safety and prevention during the application of torch-applied
polymer-modified bitumen sheet products. The potential for fire is of specific concern
during the installation of torch-applied membrane flashing sheets over combustible
substrates such as wood roof decks and wood blocking. NRCA believes torch-applied
polymer-modified bitumen products can be safely used, even over combustible substrates,
if the roof membrane and construction details are properly designed and installed
with fire safety techniques taken into consideration. For a brief summary of the
CERTA guidelines, see "Specifying
The specific flashing backer intended and its configuration should be included in
designs and consistent with the membrane manufacturer's roof system requirements.
Construction details designated as "MB(T)-" in Chapter 10Construction Details
of The NRCA Roofing Manual: Membrane Roof Systems illustrate some typical CERTA-compliant
flashing configurations. The following construction details for polymer-modified
bitumen membranes depict membrane flashing configurations over combustible flashing
substrates NRCA considers appropriate.