Flat Roof Rafter Spacing

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.

Flat roof rafter spacing.

1 ft 0 3048 m. They are nailed securely to exterior wall plates and to each other. 2 are indicated below. 1 psf lb f ft 2 47 88 n m 2.

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. Dead load weight of structure and fixed loads 15 lbs ft 2. 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.

Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no. So the space between rafters can be greater without reducing the maximum span. 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. 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.

The size of rafters for a flat roof depends on the horizontal span of the building the type and grade of timber used and the load on the roof. Maximum rafter spans for a patio roof in areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot.