Flat and commercial roofing covers low-slope roof systems on warehouses, plazas, office buildings, apartment blocks, and additions with flat or near-flat roof decks. That's a different trade than the steep-slope shingle work most residential roofers do. The main systems in play around Mississauga are modified bitumen (torch-down or peel-and-stick), EPDM rubber membrane, TPO and PVC single-ply, and built-up tar-and-gravel roofs on older buildings. We've identified 12 contractors in this category who take on this kind of work locally.
What the work actually involves
Flat roofing jobs range from small patch repairs after a leak to full tear-off and re-roof on a large commercial deck. A typical project includes removing or capping the old membrane, checking and replacing wet insulation, correcting slope so water drains to the scuppers or drains instead of pooling, flashing all the roof penetrations (HVAC curbs, vents, parapet walls), and installing the new membrane system with proper seams and terminations. Ongoing maintenance, like clearing drains and resealing flashing before winter, is also part of this category and often the cheapest way to avoid a bigger bill later.
What to look for before hiring
- Manufacturer certification for the specific membrane system (EPDM, TPO, modified bitumen), since a certified installer can offer a stronger material warranty, not just a workmanship one.
- Experience with your building type: a strip mall roof, a condo podium deck, and an industrial warehouse each have different drainage, access, and code requirements.
- A written scope that specifies membrane thickness, insulation R-value, tear-off vs. overlay, and how flashing and drains are handled, not just a lump-sum price.
- Insurance and WSIB coverage, since commercial roof work often means working at height on occupied buildings.
- A clear warranty split between the manufacturer's material warranty and the contractor's labour warranty, and what voids each one.
How our scoring helps
We score each of the 12 contractors on factors like verified licensing and insurance, years doing commercial and flat roof work specifically, review consistency over time, and responsiveness to quote requests, then rank them in the guide below. The scoring method is the same across every trade we cover, so you can see exactly how the numbers are built.
See the full ranking at best roofing contractors in Mississauga, or read how we score contractors at our methodology page.
