Old Canaan Building Materials

Standing seam metal roofing is not one material. It is a profile — a sheet metal roof with raised seams running vertically down the slope — that can be executed in copper, zinc, steel, or aluminum, each of which reads differently, weathers differently, and is appropriate in different contexts. The profile alone does not make a decision. The material makes the decision.

The standing seam profile is defined by its parallel vertical ribs — the seams — running from ridge to eave. Between the seams, the flat pan of the roof is visible. In copper, the pan will develop its patina in sequence: bright, brown, near-black, then verdigris over twenty to forty years depending on exposure. In zinc, the pan will grey uniformly. In Galvalume steel, it will remain the finish color of the painted coating.

Standing seam roofing uses sheet metal panels typically 12" to 18" wide, with integral seams mechanically locked or snap-locked at the panel edges. Concealed clips attach the panels to the substrate and allow thermal movement. Metals in order of longevity and correct use for traditional New England work: copper (16 oz, 100+ year life), zinc (0.8mm, 80-100 year life), Galvalume steel with factory finish (50-75 year life). Aluminum is acceptable in coastal applications for its corrosion resistance but is softer and dents more easily.

All standing seam metals require accommodation of thermal movement — the panel clips must allow the panels to slide as they expand and contract. Restrained panels develop stress cracks at fixed points. The substrate must be solid wood sheathing, not OSB or plywood, for copper and zinc applications where the metal will move significantly. Steel standing seam can be installed over open purlins.

Standing seam metal roofing is historically correct for New England buildings from the Federal period onward on specific roof types: low-slope sections, porch roofs, dormers, bay window tops, and tower roofs. It is the correct material for the roof sections that slate and cedar shingles cannot serve.

Through architectural sheet metal contractors specializing in the specified metal. Copper and zinc require contractors with specific experience in those materials — not all sheet metal contractors work in them.