February 10, 2026 · By Jeff Therrien
How to Spot a Roof Leak Before It Becomes a Disaster
By the time water's coming through your ceiling, you're already looking at drywall repair on top of the roof bill. Catch leaks early and you save thousands. Here's what to watch for.
Inside the house
- Yellow or brown stains on ceilings or upper-floor walls - Bubbling or peeling paint near the ceiling line - Musty smell in upstairs closets or attic - Slight ceiling sag — even a small one matters - Wet insulation in the attic
In the attic
- Daylight visible through the roof deck - Dark stains on rafters or roof boards - Damp or compacted insulation - Mold on the underside of the deck - Frost on nails in winter (sign of ventilation problem that leads to leaks)
On the roof (from the ground)
- Missing or curled shingles - Damaged or rusted flashing around chimneys, vents, and skylights - Sagging gutters full of granules - Visible debris caught at a low spot
After every major storm
Walk the perimeter of your house. Look for shingles in the yard. Check ceilings for new stains over the next few days. Sarnia storms can lift shingles without obvious roof damage — you only find out when it rains again.
If you spot any of this, call me at (519) 328-2142 for a free inspection. Most early-stage leaks are cheap to fix. Late-stage leaks are not.