Flat Roof Replacement in Toronto & the GTA

You usually know when it's time. The roof over the rear addition has been patched four times, the ceiling stain keeps coming back, and the last roofer up there said the insulation squished underfoot. Searching "flat roof cost" gets you numbers from nowhere; what actually sets the price of a new flat roof is what's under yours, and nobody knows that until the tear off starts.

A proper replacement means stripping to the deck. Old flat roofs in Toronto often carry two or three layers of previous roofing, and the insulation between them is frequently waterlogged — leaving it in traps moisture against the new membrane and rots the deck from below. Strip it, fix the wood, rebuild slope with tapered insulation so water reaches the drains, then lay the new system with the flashings done patiently.

When we quote to replace a flat roof, tear off, disposal, deck allowance, insulation and membrane are itemized separately, so you can see where the money goes. And if your roof doesn't need replacing yet — if it's one bad seam on an otherwise sound membrane — the quote will say that instead. A replacement sold five years early is money down the drain, literally.

• Full tear off down to the wood deck, including old layers and wet insulation
• Deck inspection with replacement of rotted or delaminated sheathing
• New insulation above the deck, tapered where needed to build slope to drains
• New membrane system — two-ply modified bitumen, EPDM or TPO
• New metal flashings at parapets, walls and edges
• Drains, scuppers and eavestrough connections re-set at the true low points
• Sealing and detailing at every vent, stack and skylight curb
• Disposal bins, magnet sweep and full site cleanup

• How many layers come off — each old roof adds labour and disposal weight
• Wet insulation, which is heavy to remove and always means more of it than you hoped
• Deck repairs uncovered mid-job; a good quote carries a stated per-sheet allowance so surprises are priced up front
• Whether the roof needs tapered insulation to correct ponding, or already drains
• Access — bin placement, laneway versus street, and how high the roof sits
• Count of penetrations, walls and skylights; details are where the hours go
• Membrane system chosen and the insulation R-value you want above the deck

Every home is different, so we don’t publish flat prices — the quote is free and based on your actual job.