What is a Torch Down?

Torch down roofing (also known as "torch on" roofing) gets its name from the fact that an open-flame propane torch is required for installation. Sheets of modified bitumen are rolled out onto the roof, and a roofing professional uses a hand-held propane torch to heat the material and glue it to the surface. Once the layers reach the right temperature, the seams are melted together to form a watertight seal.

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The membrane layers of a torch down roof are made of bitumen, an asphalt mixture that has been treated with rubber or plastic. This form of roofing has the benefit of not melting or splitting as it stretches and shrinks. It can withstand the extremes of heat and cold that it will experience on the roof as the seasons change. Torch down roofing is available in two-layer and three-layer systems.