When should I replace garage roof flashing in the NB climate?

Garage roof flashing in New Brunswick should be inspected every 3-5 years and typically needs replacement every 15-25 years, depending on the material and exposure to NB's harsh freeze-thaw cycles, ice dams, and coastal weather conditions.

New Brunswick's climate is particularly hard on roof flashing because of the extreme temperature swings, heavy snow loads, and persistent moisture from our Maritime environment. Galvanized steel flashing — still common on older NB garages — typically shows rust and deterioration after 10-15 years and should be replaced before it fails completely. Aluminum flashing lasts 20-25 years in most NB locations, while copper flashing can last 50+ years but costs significantly more upfront.

Ice dams are the primary flashing killer in New Brunswick. When snow melts and refreezes at the roof edge, the expanding ice forces water up under shingles and behind flashing. This is especially problematic where garage roofs meet house walls on attached garages, in roof valleys, and around any roof penetrations like vents or chimneys. The step flashing where a garage roof meets a house wall takes the worst beating — inspect this area closely every fall for loose pieces, gaps, or rust spots.

Signs your garage roof flashing needs immediate attention include rust stains on siding below the flashing, water stains on interior garage walls or ceiling, loose or missing flashing pieces after windstorms, and any visible gaps where flashing meets the roof or wall. In NB's climate, small flashing problems become major water damage quickly because our long winter season prevents proper drying between moisture events.

Timing matters for flashing replacement in New Brunswick. The best window is late spring through early fall when temperatures are consistently above 5°C and roofers can properly seal all connections. Flashing work requires removing and reinstalling shingles, applying roofing cement, and ensuring all joints are weathertight — work that's difficult or impossible in freezing temperatures. Many NB roofers won't warranty flashing repairs done between November and March because cold temperatures prevent proper adhesion of sealants.

Coastal NB locations (Saint John, Shediac, Bathurst shoreline) should inspect flashing more frequently because salt air accelerates corrosion of galvanized and aluminum materials. Northern NB communities with heavier snow loads should pay special attention to valley flashing and areas where snow accumulates against walls or in roof angles.

When to Hire a Professional

Flashing replacement requires working at height, properly integrating new flashing with existing roofing materials, and understanding how water flows on your specific roof design. A professional roofer familiar with NB conditions will know to install extra ice and water shield membrane, use proper fastening techniques for high winds, and ensure all flashing extends well up under the shingles. Improper flashing installation is one of the most common causes of roof leaks in NB garages, and the water damage from a failed repair often costs more than hiring a professional initially. Expect to pay $15-$35 per linear foot for professional flashing replacement, with step flashing at wall intersections at the higher end of that range.

Need help finding a roofing contractor experienced with NB's challenging climate? Browse roofing professionals through the New Brunswick Construction Network directory.