Torch-applied polymer-modified bitumen sheet products have been used successfully and safely in North America since the late 1970s; however, in a limited number of situations, rooftop fires have occurred during the application of these products.
NRCA is of the opinion torch-applied polymer-modified bitumen sheet products can be used safely if roof decks, roof membranes and construction details are designed properly and installed with fire safety techniques taken into consideration. NRCA recommends designs be based on guidelines contained in The NRCA Roofing Manual and torch-applied applications should only be carried out by CERTA-trained workers.
The NRCA Roofing Manual
Torch-applied polymer-modified bitumen sheet products are addressed in The NRCA Roofing Manual: Membrane Roof Systems—2019. Specific assembly configurations for which NRCA recommends torch-applied products are described in Chapter 1-Roof Assembly Configurations. These include torch-applied roof systems over non-nailable (concrete) and insulated roof decks except combustible (wood) roof decks.