Torch-Applied Roofing

Torch-applied (torch-down) roofing uses a propane torch to melt modified bitumen sheets onto the roof. It’s a common cause of serious building fires, because heat travels into gaps, edges and insulation where a fire can smolder unseen for hours.

• Roofers
• Construction

Never torch where you can’t see

Fires start when flame or heat gets into places the roofer can’t see. Don’t torch directly at:

• Gaps at roof edges, parapets, curbs, vents and penetrations
• Inside corners and seams over wood or combustible insulation
• Wood nailers, flashings and siding next to the roof
• Roof drains and openings into the building
• Old roofs with hidden debris or dry material underneath

In these areas, use a non-torch method like a hot-air welder, self-adhered membrane or cold adhesive, or heat the membrane away from the roof and set it in place.

Propane cylinders and torches

• Cylinders upright, secured and away from roof edges and the torch flame
• Hoses inspected for cracks and leaks; leak-tested with soap solution
• Torch never set down while lit; use the stand
• Torch shut off at the cylinder when not in use
• Only the amount of propane needed for the day kept on the roof

See Propane.

Extinguishers and fire watch

• Keep a fully charged fire extinguisher within reach of every torch.
• Keep a fire watch after torching stops. Roofing industry guidance (the CERTA program) calls for watching for at least 2 hours after the torch is turned off, and many insurers and fire codes require one. Check the area with an infrared thermometer or camera if available.
• Know how to report a fire and where the building’s alarms and exits are.

Training

The National Roofing Contractors Association’s CERTA (Certified Roofing Torch Applicator) program trains roofers in torch safety, and many owners, insurers and fire codes require it.

Last updated: October 2, 2026