Short answer
Most flat roofs in Toronto use one of three membranes: TPO, EPDM or modified bitumen. All three give long-lasting waterproof protection. The right choice depends on how the roof will be used, what's already there and the details around drains, walls and equipment.
A flat roof has a pitch of 10° or less. They’re common on Toronto homes, additions, garages and commercial buildings, and more people are turning them into usable space.
The three main membranes
TPO (thermoplastic polyolefin). A single-ply membrane, usually white or light grey, with seams that are heat-welded together. The light colour reflects sunlight, which helps keep the building below cooler in summer.
EPDM (rubber). A single-ply synthetic rubber membrane, usually black. It stays flexible through freeze-thaw cycles and has a long track record on Canadian roofs.
Modified bitumen. Asphalt reinforced and modified for flexibility, installed in layers. It is tough and handles foot traffic well, which is why it’s often chosen where people will walk on the roof.
We install all three. During your estimate we look at the existing roof, the drainage and how you use the space, then recommend the one that fits.
What matters as much as the membrane
- Drainage. Water pooling on a flat roof is the most common cause of problems. Drains, scuppers and a slight slope need to move water off quickly.
- Edges and penetrations. Most leaks start where the membrane meets a wall, drain, skylight, vent or HVAC unit, not in the middle of the roof.
- Insulation. Re-roofing is the best time to add insulation under the membrane.
Using your flat roof
A flat roof can become a deck, a patio, a rooftop garden or even a greenhouse. It’s also a convenient place for HVAC equipment, and it gets sun all day, which suits solar panels. If you’re planning any of these, tell us before the roof goes on, so the membrane and protection layers are chosen for the extra weight and foot traffic.
Maintenance
Have a flat roof checked at least every six months. Clear debris from drains, and look for pooling water, blisters or cracks. Small repairs on a flat roof are inexpensive; water that’s been getting in for a season is not.