Pro Torch Roofing replaced the failed flat roof on a home in Coquitlam with a 2-ply SBS torch-on membrane, upgraded roof drains and heavier-gauge custom metal. At this elevation snow sits on the roof for weeks, so the system was specified for ponding, freeze-thaw and ice at the drains. Expected service life: 25–30 years.
The challenge
Flat roofs in the higher parts of Coquitlam live a harder life than the same roof in Richmond. Snow loads up, melts from underneath, refreezes at the drains and then sits as a pond on top of the membrane for weeks. The original roof had almost no slope, undersized drains and a single-ply membrane that had split along a seam under exactly that kind of ice dam. Water was coming through the ceiling of an upstairs bedroom.
What we did
Tear-off and slope correction
We stripped the roof to the deck, replaced water-damaged sheathing and installed tapered insulation to give the roof positive slope toward new drain locations. Standing water is the enemy of every flat roof; on a snow roof it is worse.
Drains and overflows
New cast drains with clamping rings and strainers, plus overflow scuppers through the parapet so that if the drains ice up the water has somewhere to go other than the bedroom.
2-ply SBS torch-on
Torch-applied SBS base sheet and granulated cap sheet, all laps torched and probed, with reinforced flashings up every parapet. Heavier-gauge custom metal cap flashings were bent in our shop to stand up to snow shovels and ice.
The result
A roof that drains, with a second way out for meltwater and a membrane that tolerates ponding without complaint. The owners received drone photos of the finished roof and a written warranty.
Slide through the job. Tap any photo to enlarge.
Watch the Coquitlam flat roof replacement
Filmed on site in Coquitlam: tear-off, new slope and drains, and the 2-ply torch-on membrane going down.
Questions about flat roofs in Coquitlam
How much does a flat roof replacement cost in Coquitlam?
Pro Torch Roofing installs 2-ply SBS torch-on at $10–$20 per square foot. Tapered insulation, new drains and overflow scuppers add to the cost but are what keep a snow roof dry.
Is torch-on good for snow and ice?
Yes. SBS modified bitumen stays flexible in the cold, tolerates standing water and handles freeze-thaw cycles better than single-ply membranes, which is why we specify it for the North Shore and Tri-Cities hillsides.
Why add overflow scuppers?
When drains ice over, meltwater rises until it finds the lowest weak point — usually a door or a wall flashing. A scupper through the parapet gives it a safe exit.
Should I shovel my flat roof in winter?
Only if the load is extreme, and then with a plastic shovel, leaving a few centimetres on the membrane. A properly sloped 2-ply roof with clear drains rarely needs it.
Flat roof in the Tri-Cities?
Free drone inspection and written estimate. We call back within two business hours.
