5 Critical Signs Your Ontario Home Needs Immediate Roof Repair

Published: December 1, 2025 | By Principal Roofing Editorial Team

A roof leak is rarely a sudden event. In almost all cases, a leak is the result of months — or even years — of slow degradation that went unnoticed. Especially in Ontario, where our roofs experience extreme summer heat and sub-zero winter freeze-thaw cycles, performing regular visual checks is vital. Here are the 5 warning signs that your roof needs a professional inspection and repair.

1. Granules in the Eavestroughs (Gutters)

Asphalt shingles are coated with mineral granules that protect the underlying asphalt from UV radiation. As shingles age and wear, these granules loosen and wash into your gutters. If you clean your eavestroughs and find piles of dark sand-like granules, your shingles are losing their protective layer. Without granules, shingles quickly dry out, crack, and leak.

2. Curled, Cracked, or Missing Shingles

Walk around your property and look up at the slopes of your roof. Are any shingles curling upwards at the corners, buckled in the middle, or showing cracks? Shingles should lay completely flat. Cracked or curled shingles can easily blow off in high winds, leaving the wood roof deck completely exposed to rainwater.

3. Water Stains on Your Attic Ceiling or Walls

You don't need to wait for a storm to check your roof. Grab a flashlight and carefully head into your attic. Inspect the rafters, roof decking, and insulation for dark water stains, mold growth, or damp spots. Even a small, slow drip can lead to rot in the roof deck and structural damage over time.

4. Damaged or Rusted Flashing

Flashing consists of thin metal sheets installed along valleys, chimney bases, skylight edges, and vent pipes to direct water away from seams. If your flashing is rusted, bent, cracked, or has separated from the brick or shingle line, water will find its way inside. Flashing issues are the single most common cause of household roof leaks.

5. Sagging Roof Deck

If you notice a sag or depression along the ridge line or slopes of your roof, this is a sign of structural deck damage. It usually indicates that water has leaked through the shingles and rotted the plywood decking below, compromising its load-bearing strength. This requires immediate attention from a certified roofing specialist.