Roof Rafter Spacing

Since most sheets are 4 x8 typical rafter spacing are 12 16 24.

Roof rafter spacing.

Structures such as sheds or barns can be frames with rafters every 24 again make sure to consult local codes. Rafter spacing is based on the width of the metal roofing panels. If your local building authority has a rafter spacing code you may not space rafters wider than required by code. 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.

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 the us they are typically spaced at fractions of the roof sheathing size. Use these two tables for roof rafters with a slope greater than 3 in 12. The same concept holds true for roof trusses.

It is always better to have a large rafter rather than be concerned with a sagging roof. In california 16 is by far the most common for residential construction. Wider panels allow for greater spacing between rafters. Rafter spacing rafters must be strong enough to hold the roof sheathing and the shingles.

The above spans are based on american softwood lumber standard sizes. If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center.