One of the most common types of roofing seen used on flat roofs today is modified bitumen or rubberized asphalt, commonly referred to as torchdown roofing. A torch melts the asphalt onto the flat roof, creating an impermeable roof with protection from rainwater. The asphalt material generally comes in rolls and is applied with a torch or open flame. The process got its name from the installation process. Sheets are laid on the roof, and torched in the overlaps areas. Torchdown is available in smooth and granulated and can be installed as a single-ply or dual-ply system.
When Torchdown roofing was first introduced to the roofing industry it was appealing due to its lower cost over hot tar roofing. However, this has been overcome by the increased cost of liability insurance associated with having an open flame on the roof. A small percentage of roofing contractors carry the proper insurance to work with torchdown roofs.