A new membrane roof on a single-storey home in Georgina, on a street of similar low-slope homes. The old white-coated roof was laid in sections, and every joint between them had been patched.
We taped every old seam first, primed the whole deck, then rolled out a new black membrane in overlapping courses from one end of the house to the other, carried up and around the rooftop air conditioner and the roof vent. The photographs run from the finished roof back through each stage.
The Georgina page covers the rest of the work we do in town.
What was on the roof when we got there
The sixth photograph is the roof as we found it: a white-coated low-slope surface laid in sections, with the joints between them patched over the years.
A flat roof is unforgiving in a way a pitched one is not. Water does not run off it in seconds, it sits, and it finds any joint that has opened even slightly. On a roof like this the seams are the problem, so the job was to replace a surface made of many seams with one that has as few as possible.
Seams, primer, then membrane
Before anything new went down, the crew taped every old seam with a self-adhered flashing tape. You can see the release liner from it lying on the roof in the sixth and seventh photographs. That gives the new layer a flat, sealed surface to sit on rather than a ridge at every joint.
The whole deck was then primed, the glossy black coat in the eighth photograph, so the membrane bonds to the roof rather than simply resting on it. The membrane itself came on the roof in rolls and went down in overlapping courses, heat-welded at the laps. The propane cylinders in the ninth photograph are for the torches.
Every course laps the one before it, so the finished roof in the first four photographs reads as long dark bands with a lap line between each. That overlap is the entire point: there is no butt joint anywhere for water to work into.
The detail around the air conditioner
The fifth photograph is the one that matters most on a roof like this. A rooftop air conditioner and a roof vent are both holes in the roof, and they are where flat roofs leak first. The membrane is carried up around the base of each, with extra strips laid at the corners where the field of the roof meets the curb.
If you have a low-slope roof with equipment on it, that junction is the first place to look after a winter. Our guide to roof flashing in Ontario explains why the joints, not the open field of the roof, are where water gets in.
Low-slope roofs in Georgina
Georgina sits on the south shore of Lake Simcoe, and a flat roof here spends the winter under snow that melts and refreezes on the surface rather than sliding off. That is what tests the laps. A continuous, well-lapped membrane is what keeps that meltwater on top of the roof instead of in the ceiling below.
We work across Georgina from our yard in Gormley, including a siding, soffit and fascia job in Jackson's Point. If your low-slope roof is patched more than it is roofed, get a free quote and we will look at it before the snow arrives.