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 CERTA."
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 10—Construction 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.