Builders aren t bound by standard rafter spacing measurements.
Roof rafter spacing 2x4.
If you live in an area that requires a shed roof rafter to support a heavy load then an spf rafter can only span 7.
It is always better to have a large rafter rather than be concerned with a sagging roof.
If your local building authority has a rafter spacing code you may not space rafters wider than required by code.
But they do tend to space rafters in one of several industry standard increments typically either 12 16 or 24 inches apart.
1 ft 0 3048 m.
Span calculator for wood joists and rafters also available for the.
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.
Rather than having 2 4 purlins every 12 it would make far more sense economically to use 2 6 purlins every 24.
Both of these are for light roof loads.
Rafter span tables use these tables to determine lengths sizes and spacing of rafters based on a variety of factors such as species load grade spacing and pitch.
Typical rafter spacing codes will specify a minimum spacing of 16 inches 19 2 inches or 24 inches.
Live load psf dead load psf span calculator for wood joists and rafters available for the iphone.
As mentioned above a 2 4 spf shed roof rafter can span 11.
Structures such as sheds or barns can be frames with rafters every 24 again make sure to consult local codes.
Spacing in exterior exposure.
There is no standard spacing it depends on what size of rafters you want to use and the span of your shed.
2 are indicated below.
An syp rafter can span 11.
For instance 2 grade 2x4s at 16 on center will span just over 9.
Without even running the calculations i would say there is a good chance the 2 4 purlins will not make the deflection criteria required for a roof framing member supporting steel.
Dead load weight of structure and fixed loads 15 lbs ft 2.
1 psf lb f ft 2 47 88 n m 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.
Rafters must be strong enough to hold the roof sheathing and the shingles.