Can one roofer find a leak another Calgary company missed?

Yes, and it happens more often than homeowners expect. Roof leaks are genuinely difficult to diagnose because water travels along rafters, sheathing and vapour barriers before it drips, so the wet spot on your ceiling can be a metre or more from the actual entry point. A second roofer with fresh eyes and a different inspection method often finds what the first one missed.

Why the First Roofer May Have Missed It

The most common reason is that the first inspection focused on the obvious: missing or cracked shingles, damaged vent boots, open seams. But many Calgary leaks come from subtler sources. Ice dams are a classic example. With roughly 128 freeze-thaw cycles a year, water backs up under shingles at the eave, and the damage shows up on an interior wall or ceiling long after the ice is gone. If the first roofer came out in summer, they may have seen no sign of it from the roof surface.

Other frequently missed sources include step flashing where a roof meets a wall or dormer, the counter-flashing at a chimney, cracked pipe boot collars, and nail pops under a shingle tab that look fine from three metres away. On flat or low-slope roofs common on Calgary garages and additions, a small blister or a seam separation in the SBS membrane can be invisible unless someone probes it.

The second roofer should do more than walk the surface. A thorough inspection includes checking the attic for water stains, daylight, frost or mould, which often pinpoints the entry zone more reliably than the roof surface does. They should also run a hose test on suspect areas in sections, working upward from the eave, rather than soaking the whole roof at once.

Do not walk the roof yourself after rain or in winter. Alberta's OHS Code requires fall protection for anyone working at 3 metres or more, and a wet or icy shingle surface is dangerous even for experienced tradespeople.

A paid inspection from the second roofer, typically $150 to $400 for a standard house or $450 to $700 for a written report with photos and measurements, is worth it when a repair has already failed. Ask specifically for a written scope that identifies the entry point, the travel path and the proposed fix, not just a quote for new shingles.

When you get that quote, confirm it covers the actual source and not just the symptom. A fair repair quote for a flashing issue or a moderate leak in Calgary runs roughly $1,000 to $3,000; if there is deck rot or structural damage underneath, expect $3,000 to $5,000 or more. Make sure the quote includes replacing any vent boots and flashings disturbed during the repair, because reusing old collars on a fixed roof is one of the reasons leaks come back.

Before you sign anything, check that the roofer holds an Alberta prepaid contracting licence (searchable on Service Alberta's website) if they are asking for a deposit, and request a WCB-Alberta clearance letter to confirm their account is in good standing. Get the scope, materials, price, start date and payment terms in writing.

If you do get that second look, ask for a written diagnosis of where the water gets in, not just a repair price.