Roof Rafter Spacing

In the us they are typically spaced at fractions of the roof sheathing size.

Roof rafter spacing.

It is always better to have a large rafter rather than be concerned with a sagging roof. Typical rafter spacing codes will specify a minimum spacing of 16 inches 19 2 inches or 24 inches. If your local building authority has a rafter spacing code you may not space rafters wider than required by code. Rafter spacing is based on the width of the metal roofing panels.

The same concept holds true for roof trusses. Structures such as sheds or barns can be frames with rafters every 24 again make sure to consult local codes. Rafter span tables use these two tables for roof rafters with a slope of 3 in 12 or less. Since most sheets are 4 x8 typical rafter spacing are 12 16 24.

The above spans are based on american softwood lumber standard sizes. A metal roof must also allow for some overlap on each side of the panels which will reduce the effective width of the panel. 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 spacing rafters must be strong enough to hold the roof sheathing and the shingles.

So the space between rafters can be greater without reducing the maximum span. Use these two tables for roof rafters with a slope greater than 3 in 12.