Torch down roofing (sometimes referred to as “torch on” roofing) is so named because it requires an open-flame propane torch. In this installation method, 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 adhere it to the surface. Once the layers reach the right temperature, seams are melted together to create a waterproof seal.
The membrane layers of a torch down roof are made of an asphalt compound called bitumen that is modified with either rubber or plastic. The main strength of this type of roofing is that it can expand and contract without melting or cracking. It has a high tolerance for both the heat and the cold it will experience on the roof during the change of seasons. There are different types of torch down roofing including two-layer and three-layer systems.
There are two main types of torch down roll roofing: two-layer systems and three-layer systems. Both systems have a base and cap sheet, but in the three-layer system, the roofing professional will apply a base sheet, then a smooth cap sheet, and finish with a granule cap sheet. This extra layer helps extend the life of the roof and usually enhances fire resistance, energy efficiency, color, or other features.
There are many advantages to torch down roofing. The first job of any roof system is to keep water out of the building/structure, and torch down roofing has excellent water-resistant properties. Provided the membrane and insulation are installed according to manufacturer application instructions, the flat surface of a torch down roof prevents water from collecting and allows it to drain off.
Torch down roll roofing is designed for all climates, expanding under heat and contracting under cold conditions without melting or cracking as other materials might. It’s this ability that gives torch down roofs their long lifespan.