Corrugated vs standing seam metal: which for a house?

Corrugated and other exposed-fastener panels are everywhere on the rural side of the region: barns, shops and farmhouses in Metchosin and Central Saanich, cabins toward Sooke, and the simple gabled homes on Highlands acreages where the roof is a big rectangle and the budget has to cover an outbuilding too. On those roofs the panel does its job for decades and nobody sees the screw heads from the road.

Standing seam dominates in the core and on the water. Cordova Bay, Dallas Road and the Sidney and North Saanich waterfront put salt and wind on every screw, and a concealed-fastener panel with the right coating simply has fewer places to corrode. In Fairfield, Oak Bay and Fernwood the argument is looks and complexity: a cut-up roof with dormers and valleys needs the hemmed, clipped details that standing seam crews are set up to do.

A corrugated or ribbed panel is fixed with hundreds of screws driven through the face, each sealed by a neoprene washer. The washers are the roof's weak point: UV and thermal cycling harden them over 15 to 20 years and they need checking and eventually replacing, and every screw is a place where a slightly over-driven or under-driven fastener can weep. Standing seam panels are held by clips hidden under the raised seam, so the weather surface is unbroken from ridge to eave and the panel can expand and contract freely.

That is why exposed-fastener metal is cheaper to buy and install, and why standing seam is what installers recommend on roofs that are hard to get back onto.

Corrugated is not a compromise everywhere.

• Outbuildings, shops, barns and carports where a screw check every 15 years is no hardship
• Simple gabled rural homes with easy roof access and few penetrations
• Budget-driven replacements where the alternative is another asphalt roof, not standing seam
• Rustic or agricultural designs where the rib pattern is the intended look
• Low-slope roofs where a suitable exposed-fastener panel is specified for the pitch

Choose standing seam for waterfront and wind-exposed sites, for cut-up roofs with valleys, dormers and multiple penetrations, for homes where the roof is visible from the street and the neighbours, and for any roof you do not want a crew climbing every 15 years. Specify the metal for the site: aluminum or a coastal-grade coated steel near salt water, with matching flashings and fasteners. Ask for concealed-fastener panels with hemmed eaves and properly formed valleys, and check that the installer has done standing seam residential work locally, because the detailing is the difference between a 20-year roof and a 50-year one.

For most Greater Victoria houses, the gap between the two tiers is a few thousand dollars on a roof meant to last four decades, which is why standing seam is the usual answer in town.