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Flat Roof Skylight Repair in Toronto. Fix the Curb. Save the Roof.
Most leaking skylights don't need a new skylight — and they definitely don't need a new roof. They need the curb waterproofed properly, with your roof system's materials, to the skylight manufacturer's exact requirements. That's precisely what we do.
Book a Skylight Assessment Call 416-826-1334Wrong materials, wrong hands, wrong sequence.
Here's the pattern behind almost every leaking skylight we repair: the skylight was installed after the roof was already finished — usually by a general contractor, not a roofer. And to waterproof the curb, they used whatever materials they had on the truck: products completely different from the existing roof system, often outright temporary materials meant to last a season, not a decade.
A flat roof membrane is a chemical system. Foreign materials don't bond to it, don't move with it through freeze-thaw, and don't seal it — they just delay the leak long enough for the contractor to be gone.
The #1 cause of skylight leaks isn't the skylight. It's a curb that was never waterproofed properly in the first place.
A "small" skylight leak is never small inside.
Skylight leaks run hidden inside the curb and ceiling cavity long before they show. By the time we're called, this is what's usually waiting under the flashing:
The wooden deck and curb framing around the skylight soaked and rotted — the most common damage we uncover, and the reason repairs must include honest carpentry.
Saturated insulation around the opening — no longer insulating, feeding condensation, and spreading moisture sideways into the roof assembly.
Ceiling marks, bubbling paint, soft drywall around the skylight well — the visible tip of everything above it.
Warm, wet, enclosed cavities are mold's favourite home — one more reason a skylight leak is worth opening properly, not caulking over.
We repair all of it in one scope: deck and curb carpentry, insulation replaced, flashing rebuilt — documented with photos, including for insurance claims where the damage qualifies.
Curbs off manufacturer spec cause condensation and air leaks.
Water isn't the only thing a bad curb lets through. Every skylight manufacturer publishes exact curb requirements — height, dimensions, insulation, and sealing. When the curb doesn't match them (and improvised curbs almost never do), two chronic problems follow:
Condensation — the unit sits wrong on its curb, thermal bridges form, and interior humidity condenses around the skylight: drips and stains with no rain in sight, endlessly misdiagnosed as a leak.
Air leaks — gaps between curb and unit let conditioned air escape all year: cold drafts pouring down the skylight well in winter, heat gain in summer, and energy bills paying for both.
Our repairs rebuild the curb to the manufacturer's exact requirements — sealing water, air, and the condensation pathway in one job.
Condensation from a thermal-bridged curb — not a leak, and no caulking will ever fix it.
Winter air leaking through curb gaps that don't meet the unit's specified dimensions.
The same gaps working in reverse — plus energy bills quietly paying for the mistake year-round.
Don't replace your entire roof because a general contractor made it leak.
We see it constantly: a skylight curb leaks, water spreads, and the next roofer through the door quotes a full replacement. The roof was never the problem — the curb was. We're pros at exactly this repair, and it costs a fraction of the roof you're being sold. Give us a call first.
Call 416-826-1334 Before You SignResidential, commercial, industrial — standard and custom.
Homes, additions, and laneway suites — curbs rebuilt, wells repaired, and units from VELUX and FAKRO serviced or replaced to spec.
Multi-skylight roofs, warehouse domes, and curb rows on commercial buildings — repaired in sections with tenants operating below.
Odd sizes and custom openings matched with units made to order from any manufacturer — including Canadian-made Columbia Skylights — to fit your exact needs.
Opened honestly, rebuilt to spec, tested wet.
Water testing and inspection isolate leak vs. condensation vs. air leak — so we fix the actual problem, once.
Flashing opened, deck and curb framing probed, insulation checked — the honest damage picture, photographed.
Rot replaced, curb rebuilt to the skylight manufacturer's exact requirements, membrane tied in with your roof system's own materials.
Flooded on the spot to prove it, then independent inspection — you pay after it passes.
Skylight repair questions
Why is my flat roof skylight leaking?
Almost always because the curb was never waterproofed properly. Most skylights are installed after the roof is finished, by general contractors who use whatever materials they have — products foreign to the existing roof system, often temporary ones. Those materials don't bond to the membrane and fail at the curb. The skylight unit itself is rarely the problem.
Do I need to replace my roof because of a skylight leak?
Almost never — and don't let anyone sell you one before the curb is tested. A skylight curb leak spreads water that mimics roof failure, and full replacements get quoted for what is actually a curb repair at a fraction of the cost. Test first, then decide.
What damage does a skylight leak cause inside the roof?
The usual findings when we open a leaking curb: rotted wooden deck and curb framing, saturated insulation, stained and softened drywall around the skylight well, and frequently early mold. The repair scope covers all of it — carpentry, insulation, and flashing — documented with photos for insurance where applicable.
My skylight drips but only in winter — is that a leak?
Very likely condensation, not a leak. When the curb doesn't match the skylight manufacturer's exact requirements, thermal bridges form and interior humidity condenses around the unit — drips and stains with no rain in sight. The fix is rebuilding the curb to spec, not caulking or membrane work.
Why is there a cold draft under my skylight?
Air leaking through gaps between the curb and the unit — a symptom of a curb built off the manufacturer's specified dimensions. It costs comfort in winter, heat gain in summer, and energy bills all year. Rebuilding the curb to spec seals water and air together.
Can you repair any skylight brand?
Yes — residential, commercial, and industrial skylights from any manufacturer, standard or custom-made, including VELUX, FAKRO, and Columbia Skylights. Where a unit genuinely needs replacing, we order the correct or custom-made unit directly and install it to both the skylight and membrane manufacturers' requirements.