Without being technical about the chemical compounds involved, Torch On Roofing generally consists of two plies of Modified Bitumen Membrane. Each ply, or layer, is approximately 3 – 4 mm. thick.
The base ply is either mechanically secured (with screws through large washers referred to as “plates”) or attached to the substrate with adhesive. The cap sheet is similar in composition, but often has a granulated surface to provide protection from the elements.
Both the top surface of the base sheet and the bottom face of the cap sheet have a thermofusible plastic surface. (meaning they can be joined together – or fused – thermally, in this case by melting both surfaces with a propane torch) Thus the term “Torch On Roofing”.
The major advantage of Torch On Roofing is its durability. While varying with local conditions and installation practices, these roofs are expected to last an average of 25 years. Resistance to UV rays and low maintenance costs are also selling points. In recent years, costs have come down and quality has gone up, meaning that Torch On Roofing is a cost-effective alternative for flat roofs.
In our area, the principle manufacturers are Soprema, IKO and Siplast. All three offer detailed specifications and technical support to ensure that their products are applied in a prescribed manner by certified applicators. This allows the manufacturer to back up the roofing contractor’s labour warranty with their own material warranty.