Metal roofing, and the slopes where it is the only answer

Where we switch from metal to membrane

Profiled metal starts at a slope of 1 in 4, and that is also where modified bituminous membrane stops. We build a roof at 1 in 5 as a membrane roof, and one at 1 in 3.5 in metal, regardless of which covering you preferred going in. Sheet metal shingles also start at 1 in 4. Asphalt cannot go below 1 in 6 under any method.

What the roof is detailed against

We detail every metal roof to the local design values. Nanaimo's 1-in-50 wind pressure is 0.50 kPa, and we set panel gauge, clip spacing and fastener pattern from that figure, because a metal roof that fails on this coast usually fails at the fasteners rather than the panel.

Standing seam against profiled

Standing seam hides its fasteners under the seam and lets the panel move as it heats and cools. Profiled panels fasten through the face, which costs less and puts a gasket at every fastener. Both hold up here. After twenty years the difference is how many of those gaskets are still sealing.

What it costs and how long it lasts

Metal runs $8 to $30 a square foot installed and lasts 40 to 70 years, against $4 to $9 and 25 to 30 years for architectural asphalt. On a roof that will not be touched again for two generations, metal is worth the extra. On a house being sold in five years, we will usually tell you asphalt is the better buy.

Where the permit answer sits

Whether your roof needs a permit depends on which authority covers your address. We confirm that with them before the work is booked, and the quote says so.

What's included

• Standing seam metal roofing

• Profiled metal roofing

• Low-slope metal transitions

• Snow guard installation

People also ask