Roof Rafter Spacing

Wider panels allow for greater spacing between rafters.

Roof rafter spacing.

If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center. A metal roof must also allow for some overlap on each side of the panels which will reduce the effective width of the panel. In california 16 is by far the most common for residential construction. Since most sheets are 4 x8 typical rafter spacing are 12 16 24.

Rafter spacing is based on the width of the metal roofing panels. Rafter spacing rafters must be strong enough to hold the roof sheathing and the shingles. Typical rafter spacing codes will specify a minimum spacing of 16 inches 19 2 inches or 24 inches. Common spacing for trusses on this type of building is often between 2 and 4 feet but trusses built with advanced designs may allow spacing as great as 8 or 12 feet.

Rafter span tables use these two tables for roof rafters with a slope of 3 in 12 or less. If your local building authority has a rafter spacing code you may not space rafters wider than required by code. The above spans are based on american softwood lumber standard sizes. It is always better to have a large rafter rather than be concerned with a sagging roof.

So the space between rafters can be greater without reducing the maximum span. The same concept holds true for roof trusses.