The Best Roof for Victoria's Rain (and Why Rain Isn't the Problem)

The 'rainy Victoria' idea comes from the rest of the country, and the pages that rank for this question are written by Seattle and Portland contractors. The numbers say otherwise: Environment and Climate Change Canada's 1991 to 2020 normals give Gonzales 608 mm a year, with a wet December of 109 mm and a July of 14 mm. The airport in North Saanich gets roughly 45% more than the city, and Sooke is wetter and windier still, so exposure rises as you move west and north across the region. Even so, no part of Greater Victoria sees the volumes that shape roofing advice in Vancouver or the Fraser Valley.

What the rain shadow does not fix is where the water sits. A Fernwood roof under a Garry oak, the north slope of a Broadmead house, or almost any roof in the Highlands stays damp from October to April because it never sees sun, and moss follows. Sidney and the Saanich Peninsula's east shore are sunnier and mossless but take the wind and salt off Haro Strait. Dallas Road, Cordova Bay and Royal Bay get both salt and gusts. The right roof for each of these is different, and none of the differences is about millimetres of rain.

Roofs here fail early for reasons a rain gauge cannot see. Each one points to a different material choice or detail.

• Shade and moss: moss holds water against shingles and shakes, lifts edges and keeps the surface wet; north slopes and roofs under conifers are worst
• Debris: fir needles and oak leaves pile in valleys and behind chimneys, damming water above flashings
• Salt and wind: waterfront and hilltop sites see gusts that lift shingle tabs and ridge caps, and salt that corrodes ordinary fasteners and cut metal edges
• Sun: south and west slopes bake in the dry summer, which accelerates granule loss on asphalt and drying-out on cedar

Once you know which of the four applies to your roof, the material decision is usually short.

• Sunny, simple roof, moderate pitch: laminate asphalt shingles; the best value and the widest choice of crews
• Shaded roof under conifers, or a north slope that grows moss within a few years: metal, which sheds moss and needles; or asphalt with zinc or copper strips and a treatment schedule
• Waterfront or hilltop with salt and wind: coastal-grade metal (aluminum or high-grade coated steel) or wind-rated asphalt with a six-nail pattern
• Flat or low-slope sections on a mid-century home or addition: two-ply SBS torch-on, or a single-ply membrane where open flame is a concern
• Heritage streetscape with sun and airflow: cedar remains an option if you will maintain it

Where the wet season does bite is at intersections. December's 109 mm arrives as weeks of steady rain, so any weakness at a wall flashing, a chimney saddle, a skylight curb or a clogged valley gets found. A roof that is the 'wrong' material but flashed well outlasts the 'right' material flashed with sealant. Ice-and-water membrane at eaves and valleys, new step and counter flashing, and gutters that are actually clear matter more than the shingle brand.

Attic ventilation is part of the same story. Coastal humidity, not cold, drives condensation in Victoria attics, and a damp attic ages the decking from below regardless of what is on top. Any re-roof is the moment to check soffit and ridge venting.

Three questions settle most cases.

• Stand in the driveway at noon in January: is the roof in sun or in shade? Shade pushes you toward metal or a maintained asphalt roof
• Can you taste salt on the wind, or do gusts regularly lift things in the yard? Exposure pushes you toward coastal-grade metal or wind-rated shingles
• How long will you own the house? Under ten years favours asphalt; over fifteen favours metal on any roof that is not in full sun