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Flat Roofing

Flat Roof Repair in Toronto & the GTA

Water through a flat roof rarely announces where it got in. A flat roof leak shows up as a stain over the kitchen of the rear addition, but the actual breach might be a split seam three metres away — water runs along the deck until it finds a nail hole or a joint, then drops. Meanwhile the insulation soaks it up quietly, which is why a small leak ignored for a season becomes a soft, spongy patch of roof.

Most flat roof repairs are boringly specific: a lap that let go, a cracked flashing at a wall, a blistered roof section where trapped moisture has pushed the membrane up, or a drain choked with maple keys causing ponding water that works at every seam it covers. Freeze-thaw makes all of it worse — water that gets under a lap in November is an ice wedge by January.

Send photos of the roof and the interior damage and we'll quote the repair — usually a matter of a flat roof patch, new flashing detail, or clearing and re-sealing a drain. We'll also tell you plainly whether the repair buys years or months. Patching a membrane that's failing everywhere is a subscription, not a fix, and you deserve to know which one you're paying for.

What this covers

  • Leak tracing across the roof surface, not just above the stain
  • Membrane patches on splits, punctures and failed laps, matched to the existing system
  • Cutting out and re-laying blistered sections where moisture is trapped underneath
  • Re-sealing or replacing flashings at walls, parapets, stacks and skylight curbs
  • Clearing drains and scuppers, and re-setting drain seals where ponding starts there
  • Localized ponding correction with sloped patching where practical
  • Sealing around new or disturbed penetrations such as vents and AC lines
  • A straight report on the rest of the roof — what's sound, what's next

Just need one small job done?

Patch one flat-roof blister or seamClear a blocked flat-roof drain

What affects the price

  • How hard the leak is to trace — an obvious split is fast, a wandering leak takes patience
  • The membrane type; matching a patch to old torch-on differs from patching EPDM rubber
  • Wet insulation under the breach, which sometimes has to come out for the patch to hold
  • How many separate defects turn up once someone actually walks the roof
  • Access and height — a garage is a ladder job, a fourth-floor mid-rise section isn't
  • Season: emergency winter work is possible but slower and often needs a fair-weather follow-up

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

Flat Roof Repair near you

We take quote requests across the GTA. Local pages:

TorontoEtobicokeNorth YorkScarboroughEast YorkYorkMississaugaBramptonCaledonVaughanMarkhamRichmond HillAuroraNewmarketKingWhitchurch-StouffvilleEast GwillimburyGeorginaPickeringAjaxWhitbyOshawaClaringtonUxbridgeOakvilleBurlingtonMiltonHalton HillsHamiltonSt. CatharinesNiagara FallsGrimsbyNiagara-on-the-LakeBarrieInnisfilBradford West GwillimburyNew TecumsethKitchenerWaterlooCambridgeGuelphOrangeville

Common questions

Why does my flat roof leak only during some rains?
Usually because the breach only sees water in certain conditions. Wind-driven rain from one direction finds a wall flashing; a long soaking rain overtops a clogged drain and floods a lap that light rain never reaches. That's also why the leak seems to come and go — the roof isn't healing, the weather is just changing.
Is ponding water on a flat roof actually a problem?
Water that's gone within 48 hours of rain is normal. Ponding that lingers is a slow problem: it magnifies UV damage, loads the structure, breeds algae, and sits on any seam beneath it waiting for a way in. Sometimes the fix is as cheap as clearing a drain; sometimes it's a tapered patch to restore slope.
Can a flat roof be repaired in winter?
Yes, with limits. We can clear snow, trace the leak, and apply cold-weather patching or a temporary membrane to stop water immediately. Adhesives and sealants don't cure properly in the cold, so winter repairs on flat roofs are honest stopgaps — done well, they hold until a permanent repair in spring weather.
What do blisters on a flat roof mean?
A blistered roof means moisture or air is trapped between layers, expanding in summer heat and lifting the membrane. Small, intact blisters can often be left alone and watched. Big ones, or blisters that have cracked open, get cut out, dried, and patched — stepping on them or ignoring them ends the same way, with a leak.
When is membrane repair no longer worth it?
When you're calling every season and the leak is never in the same place twice. That pattern means the membrane is failing generally — brittle field, multiple soft spots, seams going one after another. At that point each patch is real money buying months, and a straight quote will price the repair and the replacement side by side.

Ready to sort out your flat roof repair?

Tell us what your roof needs — one small repair or a complete replacement — and get a free quote.

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