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Flat Roof Leak Detection in Toronto. We Find What Others Miss.
Water shows up in your ceiling metres from where it enters — and very often, the roof isn't even the problem. We diagnose with instruments before anyone touches a membrane, so you fix the real cause once.
Book a Diagnostic Emergency? Call NowThe biggest failure in roofing isn't workmanship. It's diagnosis.
General roofing companies sell what they know: new roofs. When a leak appears, the answer is almost always "replace it" — because diagnosis isn't part of their toolkit. The result? We regularly see relatively new roofs being torn off, sometimes because the original installation ignored manufacturer requirements (mandatory to pass inspection and hold a warranty), and sometimes because the roof was never the problem at all.
The most expensive sentence in roofing: "We replaced the roof — and it still leaks."
We see it constantly: a full replacement, thousands spent, and the same stain reappears with the next rain — because the core issue was never found during inspection. A new roof is not a diagnosis. Finding the actual water path is.
What looks like a roof leak often isn't the roof.
Not every stain needs a new membrane — and most don't need a replacement at all. These are the culprits we actually find, week after week, on Toronto flat roofs:
Winter's great impostor — interior humidity condensing in the roof assembly. No membrane repair can fix it; ventilation and insulation can.
A clogged scupper or overflowing gutter sends water over the edge and into walls — mimicking a roof leak perfectly.
One of the most common real sources: water entering through parapet caps and masonry, far from any membrane defect.
Cracked stucco and failed wall details let water in above the roofline — the roof gets blamed, the wall is guilty.
A $30 bead of failed caulking where the membrane terminates causes leaks that trigger $30,000 replacement quotes.
Aged domes, failed curb flashing, and fogged seals — skylight inspections are part of every diagnostic we run.
HVAC curbs, condensate lines, and unit penetrations are chronic leak sources — especially after equipment swaps.
Sometimes it really is the roof — punctures, open seams, blisters. Then we pinpoint it and repair that spot, not the whole roof.
Whether it's condensation, an overflow, or a failed detail — the fix is only right if the diagnosis is. That's why diagnosis is the service, not an afterthought.
Every tool, for every problem — matched, never guessed.
Infrared Thermal Scanning
Thermal imaging reads the roof's heat signature to reveal saturated insulation and trapped moisture invisible from the surface — mapping exactly how far water has travelled.
Smoke Screen Detection
Theatrical-grade smoke introduced under the membrane escapes through breaches — making the exact entry point visible, even on complex multi-layer roofs.
Controlled Water Testing
Systematic zone-by-zone flooding isolates the leak path deterministically — including scupper and drain overflow scenarios that mimic membrane leaks.
Moisture Metering & Mapping
Probe and scan readings across the assembly quantify what's wet and what's dry — the evidence that separates condensation from intrusion.
Aerial & Detail Inspection
Drone surveys and close inspection of parapets, stucco lines, skylights, AC curbs, and terminations — the details where most "roof leaks" actually start.
Core Sampling
When the assembly itself is in question, a test core reveals layers, saturation, and deck condition — the same transparency we bring to replacements.
Water doesn't stop at the ceiling. Neither should the search.
An active leak is a race: water entering at the roof travels through insulation, down wall cavities, across floors — and ends up in the basement. By the time it shows downstairs, it has soaked everything on the way. Emergency leak detection finds and stops the entry point fast, before a repairable problem becomes an insurance claim across three floors.
Call 416-826-1334 NowLeak detection questions
My roof was just replaced and it still leaks. How is that possible?
Because the leak was never diagnosed — only the roof was. If the real source is condensation, a parapet wall, stucco, a skylight, an AC curb, or gutter overflow, a new membrane changes nothing. We also see newer roofs that leak because they weren't installed to manufacturer requirements, which is mandatory to pass inspection and hold the warranty. Instrumented diagnosis finds the actual water path before any money is spent.
How do I know if it's a leak or condensation?
Timing and instruments. Condensation typically appears in cold weather independent of rain; leaks follow rainfall. Thermal imaging and moisture mapping settle it definitively — condensation needs ventilation and insulation work, not roofing, and no membrane repair will ever fix it.
Can a clogged scupper or gutter really imitate a roof leak?
Absolutely — it's one of the most common findings. A blocked scupper backs water up over flashing heights; an overflowing gutter drives water into the wall assembly. The stain inside looks identical to a membrane leak. A controlled water test isolates it in an hour.
Do you inspect skylights and rooftop AC units too?
On every diagnostic. Skylight curbs, domes, and seals, plus HVAC curbs, condensate lines, and penetrations are chronic leak sources — especially after equipment replacements done without proper flashing work.
What happens in an emergency leak situation?
We respond 24/7, in any weather. Priority one is finding and stopping the entry point before water travels further — from roof to walls to basement. Temporary waterproofing goes on the same visit, followed by a documented permanent repair plan, with photos suitable for insurance.
Is the diagnostic report useful for insurance?
Yes — that's often exactly why we're called. Annotated thermal images, moisture readings, and a cause-of-loss determination in the format adjusters accept. The first report is everything for a claim.
What does leak detection cost, and does it get credited?
The on-site diagnostic is free with any repair we perform. Either way, you receive an honest finding — if the fix is a $30 bead of caulking or a gutter cleaning rather than roofing work, that's what we'll tell you.