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.
Roof rafter spacing. You have to take the width of your roofing panel into the considerations. 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. Since most sheets are 4 x8 typical rafter spacing are 12 16 24. If your local building authority has a rafter spacing code you may not space rafters wider than required by code.
Determining rafter s spacing is as important as setting the metal roof purlins spacing. It is always better to have a large rafter rather than be concerned with a sagging roof. The above spans are based on american softwood lumber standard sizes. 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.
In the us they are typically spaced at fractions of the roof sheathing size. In california 16 is by far the most common for residential construction. Rafter span tables use these two tables for roof rafters with a slope of 3 in 12 or less. Use these two tables for roof rafters with a slope greater than 3 in 12.
Wider panels allow for greater spacing between rafters. Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal. A metal roof must also allow for some overlap on each side of the panels which will reduce the effective width of the panel. Our roof rafter calculator tools are handy for calculating the number of rafters needed rafter length calculator lineal feet of rafter board feed in ridge and sub facia and the total board feet in the roof.
So the space between rafters can be greater without reducing the maximum span. Typical rafter spacing codes will specify a minimum spacing of 16 inches 19 2 inches or 24 inches. The same concept holds true for roof trusses. For instance 2 grade 2x4s at 16 on center will span just over 9.
Rafter spacing is based on the width of the metal roofing panels. There is no standard spacing it depends on what size of rafters you want to use and the span of your shed. For standard shed roof rafter spacing see rafter span chart. Rafter spacing rafters must be strong enough to hold the roof sheathing and the shingles.