Roof Rafter Spacing

Wider panels allow for greater spacing between rafters.

Roof rafter spacing.

Use these two tables for roof rafters with a slope greater than 3 in 12. Typical rafter spacing codes will specify a minimum spacing of 16 inches 19 2 inches or 24 inches. Rafter span tables use these two tables for roof rafters with a slope of 3 in 12 or less. Structures such as sheds or barns can be frames with rafters every 24 again make sure to consult local codes.

If your local building authority has a rafter spacing code you may not space rafters wider than required by code. It is always better to have a large rafter rather than be concerned with a sagging roof. If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center. 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.

In the us they are typically spaced at fractions of the roof sheathing size. The above spans are based on american softwood lumber standard sizes. In california 16 is by far the most common for residential construction. A metal roof must also allow for some overlap on each side of the panels which will reduce the effective width of the panel.

Rafter spacing rafters must be strong enough to hold the roof sheathing and the shingles. Since most sheets are 4 x8 typical rafter spacing are 12 16 24.