Cause 1: Failed Seams
Seams are the most vulnerable point of any membrane system. If the torch weld was incomplete during installation, or if the seam has opened due to thermal cycling over time, water enters directly at the gap. Seam failure is particularly common at membrane terminations (edges) and at changes in direction on complex roof shapes.
Cause 2: Flashing Failures at Penetrations and Walls
Every pipe, vent, skylight, HVAC curb, and parapet wall on a flat roof requires a custom flashing. Flashings are typically the first point to fail on an aging roof — caulking dries out, metal corrodes, or the membrane around the penetration cracks from differential movement. Cossette inspects and renews all flashings as part of flat roof repairs in Gatineau.
Cause 3: Blocked Drains and Ponding Water
Flat roofs drain through internal drains or perimeter scuppers. When these become blocked by leaf matter, gravel, or debris, water ponds on the surface. Chronic ponding accelerates membrane degradation and eventually forces water through even sound membranes under hydrostatic pressure. Drain clearing is the most important and simplest flat roof maintenance task.
Cause 4: Freeze-Thaw Membrane Cracking
In the Outaouais, temperatures cross the freezing point dozens of times each winter. Any moisture that has infiltrated the membrane system expands on freezing, widening cracks and opening seams. A membrane approaching the end of its elastic life is particularly vulnerable — small surface cracks from summer UV exposure become significant failures during the first hard freeze.
Frequently Asked Questions
How do I find where my flat roof is leaking in Gatineau?
Interior water stains don’t always appear directly below the leak — water travels along the deck or insulation before dripping through. A professional inspection is the most reliable method. Cossette uses physical inspection, water testing, and in some cases infrared scanning to locate the exact breach.
Can a flat roof leak be fixed in winter in Gatineau?
Emergency temporary waterproofing can be applied in winter to stop active water entry. Permanent torch-applied membrane repairs require temperatures above freezing for reliable adhesion. Cossette can apply emergency protection immediately and schedule permanent repair when conditions allow.
Is flat roof ponding always a sign of a problem?
Some ponding for up to 48 hours after heavy rain is acceptable and will drain normally. Chronic ponding — water that remains 3 or more days after rain — indicates a drainage design or blockage issue that should be corrected. Chronic ponding significantly shortens membrane lifespan.