Torch-On Roofing for Flat and Low-Slope

Two-ply modified bitumen commonly runs 20 to 30 years, and where you land in that range depends on climate, drainage, UV exposure and detailing. Coastal BC rain, Alberta freeze thaw and Texas heat all load a membrane differently. A roof that drains within a day or two and has properly flashed penetrations reaches the top of that range. One that ponds around a blocked drain loses granules and softens years earlier.

A flat roof is never truly flat, it is built with slope toward drains. Water still sitting after about 48 hours is ponding, and it does real damage. It holds dirt and debris that abrade granules, it keeps the membrane permanently saturated, and freeze thaw cycles work at the laps. Ponding also hides the leak source, because the stain inside can be metres from the entry point.

Sometimes, if the existing membrane is sound, dry and firmly attached, and the assembly is not already at its permitted number of layers. The problem is that wet insulation under an old roof stays wet, and a new membrane torched over it traps that moisture, which turns to vapour in the sun and blisters the new cap sheet. Core cuts tell you which case you have.

Open flame over combustible decking is handled by not torching directly to it. The base sheet is mechanically fastened or set in a self-adhered or cold-applied layer, and the cap sheet is torched to that bitumen surface instead of to the wood. Work stops well before end of day so the roof can be watched for smouldering. For the specifics of each system we install, see Soprema torch-on systems.

We serve British Columbia, Alberta and Texas. Our core service area is Metro Vancouver, including West Vancouver, North Vancouver, Burnaby, and Langley.