Standing Seam Metal Roof

A standing seam roof is made of long, narrow metal panels (pans) that run from eave to ridge. Adjacent panels meet in upstanding seams, typically about 1 to 2 in (25 to 50 mm) high, which are folded, snapped or crimped together. The panels are held to the deck or purlins by clips hidden inside the seams, so the flat of the panel is not punctured. Because the clips can allow the panel to slide, the metal can expand and contract without tearing fasteners.

Variants

• Mechanically seamed: seams are folded by a seaming tool into a single lock or double lock; this is the most weathertight and usually the most expensive type.
• Snap-lock: one panel edge snaps over the other without seaming, either over clips or over an integral nailing flange.
• Batten seam: panels butt against a batten that is covered by a cap.
• Hand-formed: traditional copper, zinc and stainless roofs formed on site with tools.

Typical dimensions

Panels commonly run in continuous lengths of up to about 30 ft (9 m) on residential work and much longer on commercial roofs, with widths of about 12 to 18 in (300 to 460 mm). Narrower pans are less prone to visible waviness (oil canning).

Materials

Coated steel (usually with an aluminium-zinc coating such as Galvalume), aluminium (often 0.032 in, 0.81 mm), copper (16 or 20 oz), titanium-zinc and stainless steel are all used.

Design points

• Thermal movement is handled with fixed clips at one zone and sliding clips elsewhere.
• Engineered systems are tested for wind uplift, for example to ASTM E1592 or UL 580.
• Snow retention devices can be clamped to seams without penetrating the panels.
• Ends, ridges and penetrations need flashings that accommodate movement.

Standing seam is widely used on homes, commercial and industrial buildings, and low-slope roofs where exposed fasteners would be risky.