Why Skylight Leaks Keep Coming Back
The most common skylight leak we see is one that has already been “fixed.” Someone climbed up, ran a bead of caulk around the frame, and it held for a season. Then the freeze-thaw cycle cracked the caulk and the drip came back, usually in February.
Caulk does not fix a skylight leak because the leak is almost never a caulk joint. It is a missing piece of head flashing, step flashing that rusted through, an ice dam pushing water uphill under the shingles, or warm, humid air condensing on cold glass. Leak repair means finding which one and rebuilding that layer.
The 5 Most Common Winter Skylight Leak Sources in Toronto Homes
- Ice dams above the skylight. Attic heat melts snow, it refreezes at the cold curb and backs water under the head flashing.
- Missing or short ice and water shield. Without it, any water that gets past the shingles goes straight to the deck.
- Failed step flashing. Rusted or loose side pieces let wind-driven rain in.
- Reused flashing after a re-roof. New shingles, old skylight flashing, new leak.
- Condensation. Not a roof leak at all, but humid air hitting cold glass and an uninsulated shaft. Nearly half of our January “leak” calls end up here.
Residential Leak Repair
Kitchen Skylights
Steam increases condensation. We check the shaft before touching the roof.
Bathroom Skylights
Shower humidity is the usual culprit. Venting or shaft insulation fixes it.
Stairwell and Hallway Skylights
Head flashing and ice dam leaks show up as stains on the uphill side.
Attic Bedrooms
Deep uninsulated shafts drip on cold mornings.
Cathedral Ceilings
Low-pitch roofs hold snow longer and need crickets.
Additions With Flat Roofs
Short curbs and caulked membranes. See flat roof skylights.
Heritage Homes
Slate and copper flashing repaired by hand.
Commercial Leak Repair
Office Domes
Failed curb sealant and membrane tie-ins.
Retail Skylights
Repairs scheduled before opening.
Warehouses
Ponding at short curbs; re-tie and raise where possible.
Condo Amenity Spaces
Board-coordinated repairs with COI.
Specialty Leak Solutions
Saddle Crickets
Divert snow and meltwater around wide skylights.
Condensation Gutters and Shaft Insulation
Stop drips from humidity.
Re-Flashing With Factory Kits
Velux EDL, EDM or EDW kits matched to the roofing.
Smoke Pencil Tests
Find air leaks around frames that bring humid air to cold glass.
Materials for Leak Repair
| Problem | Repair materials |
|---|---|
| Ice dam | Grace Ice & Water Shield extended up-slope, saddle cricket |
| Flashing failure | New factory kit or aluminum step and counter-flashing |
| Transitions | Grace Vycor membrane at curb corners |
| Condensation | Roxul batt, 6-mil poly, sealed shaft |
Our Leak Repair Expertise
We have traced thousands of skylight leaks across the GTA. We know the dew point math behind January condensation, the way meltwater travels along a rafter before it shows up two feet from the skylight, and exactly which corner of a 1990s builder install usually fails first. Nine times out of ten, this is where the previous installer cut a corner.
What Actually Stops Homeowners From Fixing a Leak Properly
“It only drips when it’s really cold.”
In our opinion, that is the best clue you can give us. It points to ice damming or condensation, and both are fixable.
“I already paid someone to fix it.”
If it was caulked, it was not fixed. We find the source.
“They’ll say I need a new skylight.”
If the unit is sound, we repair it. We recommend replacement only when repair will not last.
“The ceiling is already stained.”
We can repair drywall and insulation after the leak is fixed.
Leak Repair Timeline
First Call
Leak history over the phone. Same-day or next-day visit.
Diagnostic Visit
Hose testing, thermal imaging, written cause and price.
Repair
Usually same visit or within days.
Re-Test and Report
Proof it is dry, photos for your records or insurer.
Skylight Leak Repair Cost in Toronto: What You Are Paying For
Testing and Diagnosis
The step that saves you from paying twice.
Flashing Materials
Factory kits or hand-formed metal.
Underlayment
Ice and water shield around the full curb.
Crickets
Added on wide units and snowy roofs.
Shaft Work
Insulation and vapour barrier for condensation.
Interior Repairs
Drywall and paint after the leak is fixed.
Leak Repair vs Replacement vs Installation: Which Service You Need
Sound unit, one leak source: repair. Fogged, old and leaking: residential replacement. Active storm leak right now: emergency service.
Fixed, Venting or Solar: Choosing Your Skylight Type
If condensation is the issue, a venting Velux VS or solar VSS can help by letting humid air out at the ceiling. If replacement is needed, it is the right moment to choose.
Leak Repair Timeline in Toronto: What to Expect Week-by-Week
Most leaks are diagnosed within a day or two of your call and repaired within the week. Winter jobs wait for safe roof conditions, with temporary protection in the meantime.
Why Toronto Homeowners Trust Our Leak Specialists
We test, we trace and we rebuild. No caulk-and-run. Trust us, you’re in good hands.
