Roofing Torch

A roofing torch is a large open-flame burner, usually fuelled by propane (LPG) through a hose and regulator, used to install torch-applied modified bitumen membranes. The roofer heats the underside of the roll as it is unrolled, melting a thin layer of bitumen that bonds the sheet to the substrate or to the ply below and seals the laps. Torch-applied polymer-modified bitumen has been used in North America since the late 1970s and is common in Europe and other regions.

Equipment

• Torch head and wand, with a long handle that keeps the flame at a working distance.
• Hose, regulator and cylinder, with valves and fittings suited to the fuel.
• Pilot or ignition controls on many models.
• Detail torches, smaller units for flashings and laps.
• Multi-head torch carts for large field areas.

Fire risk

Torch use is a well-recognised cause of roof and building fires. Fires often start where the flame reaches hidden combustibles: at flashings, penetrations, wall junctions, in voids beneath decks, and in insulation or debris. Smouldering fires can break out hours after work has finished.

Safe practice

Industry programmes such as the CERTA (Certified Roofing Torch Applicator) training programme, run with the US National Roofing Contractors Association, set out practices that commonly include:

• Training and certification of torch operators.
• Not torching directly onto combustible substrates or into concealed spaces; using alternative methods such as self-adhered or cold-applied materials at risky details.
• Fire extinguishers within easy reach of each torch.
• A fire watch after torching stops. Ontario's fire code, for example, requires a two-hour fire watch; thermal imaging cameras have been proposed to help find hidden hot spots.
• Proper storage and handling of propane cylinders, and turning off cylinders when not in use.

In 2019, NRCA stopped recommending torch-applied modified bitumen over combustible roof decks such as wood decks and wood panels, even with a thermal barrier, and suggested cold-adhesive alternatives; because CERTA follows the NRCA manual, the same exclusion applies within that programme. Local fire codes and insurers may impose further restrictions or bans on open-flame roofing.