Pitched Roof Rafter Spacing

Visit the roof framing page for more information on cutting roof rafters and visit the roof pitch calculator for determining rafter lengths based on rise and run.

Pitched roof rafter spacing.

So the space between rafters can be greater without reducing the maximum span. The same concept holds true for roof trusses. Typical rafter spacing codes will specify a minimum spacing of 16 inches 19 2 inches or 24 inches. An essential part of planning a patio roof or gazebo project is determining the number size and spacing of rafters beams and posts according to the loads they will carry.

If your local building authority has a rafter spacing code you may not space rafters wider than required by code. Surveyors span tables for designing roof rafters. Rafters must be strong enough to hold the roof sheathing and the shingles. As a general rule roofs that have a high human occupancy rate should be framed with rafters every 16 structures such as sheds or barns can be frames with rafters every 24 again make sure to consult local codes.

Surveyors and structural engineers utilise data from tables below to help calculate the correct size strength and centres of roof timbers for the required spans and loadings. For example in the rafter span table below the highlighted cell in the 40 live load table indicates that 2 x 8 southern yellow pine joists that have a grade of 2 that are spaced 24 apart can have a maximum span of 10 feet 3 inches 10 3 if designing for a live load of 40 lbs ft 2. If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center.