| Quick Answer:A licensed roofing contractor — such as Cossette Roofing in Gatineau — repairs flashing around chimneys and skylights. Flashing is the metal that seals these roof penetrations, and it is one of the most common sources of roof leaks. Repair involves removing or resealing the failed flashing and integrating new flashing with the surrounding shingles or membrane so water is directed away from the opening. |
Why is flashing such a common leak point?
Anywhere the roof is interrupted — a chimney, skylight, vent or wall — needs flashing to keep water out, and those transitions are where most roof leaks begin. Flashing is exposed to constant expansion and contraction, freeze-thaw movement, and aging sealant, so over time it lifts, cracks or corrodes. A roof’s field shingles can be in good shape while the flashing has quietly failed and started letting water in around the chimney or skylight.
- Flashing seals the joints where the roof meets chimneys, skylights, vents and walls.
- Freeze-thaw movement and aging sealant cause it to lift, crack or corrode.
- Most leaks start at these penetrations, not in the open field of the roof.
Who should repair it?
Flashing repair is roofing work and belongs to a licensed, insured roofing contractor rather than a handyman or a quick caulk job. In Quebec that means an RBQ-licensed roofer. Proper repair is not just a bead of sealant on top — it means integrating metal flashing correctly with the shingle courses or membrane so water sheds over it, which takes the right materials and experience. Cossette Roofing is RBQ-licensed and repairs chimney, skylight, vent and wall flashing across the region.
What does a proper flashing repair involve?
A good repair starts with finding the true source, since the leak often shows up inside away from the actual entry point. The roofer then removes or lifts the failed flashing, inspects the decking and underlayment for damage, installs or re-seats correctly profiled metal flashing, and integrates it with the surrounding roofing so water is shed away from the opening. Surface sealant alone is a temporary patch, not a lasting fix. GAF and other manufacturers provide flashing and leak-barrier components and installation guidance for exactly these details (see GAF).
Can flashing be repaired without replacing the roof?
Usually, yes. If the surrounding roof is otherwise sound, a targeted flashing repair solves the leak without a full replacement. Catching it early also prevents the water from reaching the deck, insulation and ceilings, which is what turns a modest flashing repair into a much larger job. If an inspection finds the roof is also near end of life, the roofer will tell you honestly so you can weigh repair against replacement.
What else around a chimney can cause a leak?
While failed flashing is the usual culprit, a few other issues mimic or accompany it. The chimney’s own masonry can be the source: cracked mortar joints, a deteriorating crown at the top, or porous brick can let water in independently of the roof. The chimney cap or the seal around it can fail, and condensation inside an unlined or poorly insulated chimney can show up as what looks like a roof leak. Sometimes the shingles immediately around the chimney are worn or lifted even though the flashing is intact. A proper inspection distinguishes between these, because the fix differs: flashing work for a flashing failure, masonry repair for the chimney structure, and shingle work for the field around it. Treating a masonry problem with roof sealant, or vice versa, simply lets the leak continue, which is why identifying the true source first is the part that actually saves you money.
Because the source can be any of several things, the worst response is to keep applying sealant and hope. Surface caulk over a flashing or masonry problem may stop the drip for a season, but it traps moisture and hides the real issue while water continues to reach the deck. A proper diagnosis up front — flashing, masonry, cap or shingles — means the repair addresses the actual cause once, which is both cheaper over time and far less disruptive than chasing a recurring leak through repeated patch jobs.
Frequently Asked Questions
Is a leak near my chimney always the flashing?
Often, but not always. Flashing is the most common cause, but an inspection confirms whether it is flashing, the chimney itself, or nearby shingles.
Can I just caulk the flashing myself?
Sealant is a temporary patch at best. A lasting repair re-integrates metal flashing with the roofing, which is a job for a roofer.
Does flashing repair require replacing shingles?
Sometimes a few shingles around the penetration are lifted and replaced to integrate the new flashing; the rest of the roof is untouched.
How long does a flashing repair last?
A properly integrated metal flashing repair can last many years — far longer than a surface caulk fix.
Does Cossette Roofing do flashing repairs?
Yes. Cossette repairs chimney, skylight, vent and wall flashing and will confirm the true leak source first.
Flashing around chimneys and skylights is repaired by a licensed roofing contractor, and because flashing is the most common source of roof leaks, getting it done properly matters. A lasting fix integrates new metal flashing with the surrounding roof rather than relying on surface sealant. Cossette Roofing is RBQ-licensed and repairs flashing leaks across Gatineau and Ottawa with an honest inspection first.
Key takeaways
- Flashing seals chimneys, skylights, vents and walls — and is the top leak source.
- Repairs belong to a licensed, insured roofer, not a surface caulk job.
- Proper repair re-integrates metal flashing with the roofing.
- Caught early, flashing leaks are fixed without replacing the roof.