Roof Rafter Spacing

Wider panels allow for greater spacing between rafters.

Roof rafter spacing.

In the us they are typically spaced at fractions of the roof sheathing size. Since most sheets are 4 x8 typical rafter spacing are 12 16 24. Rafter spacing rafters must be strong enough to hold the roof sheathing and the shingles. 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. The same concept holds true for roof trusses. 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.

So the space between rafters can be greater without reducing the maximum span. Rafter span tables use these two tables for roof rafters with a slope of 3 in 12 or less. 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.

Use these two tables for roof rafters with a slope greater than 3 in 12. The above spans are based on american softwood lumber standard sizes.