What are ridge cap dimensions in mm?
Short answer. Asphalt ridge cap pieces are typically about 305 to 337 mm wide, laid with an exposure of roughly 143 to 168 mm, and metric shingle strips are about 337 by 1000 mm. Metal ridge caps usually come in 10 foot (about 3048 mm) lengths, but exact sizes depend on the product, so check the maker's data sheet.
North American roofing products are made in inches or in a metric size that is very close to it, so most quoted millimetre figures are conversions.
Asphalt hip and ridge shingles
- Strip size: imperial strips are about 305 by 914 mm (12 by 36 inches); metric strips are about 337 by 1000 mm.
- Piece width across the ridge: about 305 to 337 mm.
- Exposure: roughly 143 mm (5 5/8 inches) to 168 mm (6 5/8 inches) on standard pre-formed caps.
- Cut 3 tab caps: pieces about 305 by 305 mm, commonly laid at about 127 mm (5 inch) exposure.
Metal ridge caps
- Common length: 3048 mm (10 feet), with each joint lapped by the amount the panel system specifies.
- Width: depends on the panel profile and roof pitch; order the cap made for your panel.
Tile ridges
Clay and concrete ridge tiles come in their own sizes set by each tile maker, so measure an existing piece or ask the supplier.
Working out coverage in metric
Divide total ridge and hip length in millimetres by the exposure. Example: 18,000 mm of ridge at a 143 mm exposure needs about 126 pieces, before allowing for start and finish pieces. Bundle labels list coverage, often in linear feet, so convert at 304.8 mm per foot. For converting roof slopes to metric too, see how roofers measure a roof, and for the parts themselves, roof anatomy explained.