Simplified maximum span tables for selected visual and mechanical grades of southern pine lumber in sizes 2 4 thru 2 12.
Safe spans for no 1 roof rafters.
Rafter spans can be extended slightly beyond what the rafter tables suggest when there is a cantelever extending beyond the supporting wall.
This post may contain affiliate links.
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.
While every effort has been made to insure the accuracy of the information presented and special effort has been made to assure that the information reflects the state of the art neither the west coast lumber inspection bureau the american wood council nor its members assume any responsibility for any particular design prepared from this online span calculator.
Span calculator for wood joists and rafters also available for the android os.
The 1 grade material is more expensive than the 2 grade but if you can use fewer or smaller 1 grade joists or rafters in your design you may actually save money.
2 are indicated below.
Table 9 1 in span tables for joists and rafters figure 5 gives a required compression value of 237 psi for a span of 16 feet and bearing length of 1 5 inches.
Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no.
The tables permit a bearing length of up to 3 5 inches but since 1 5 is probably the worst case that you ll encounter for joist or rafter bearing it s a safe value.
Live load is weight of furniture wind snow and more.
This table is simply a sample and may not be valid for your region.
1 psf lb f ft 2 47 88 n m 2.
Patio roof maximum beam rafter spans.
Although there is not one standard rafter spacing measurement many builders follow standard increments for simplicity.
Span calculator for wood joists and rafters available for the iphone.
View joist rafter tables.
Dead load weight of structure and fixed loads 15 lbs ft 2.
For more information see our disclosures here.
Sample maximum spans feet inches douglas fir or larch no 1 or no 2 with 31 3 psf of snow loading.
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.
1 ft 0 3048 m.
The maximum spans in the table above are for the horizontal distance the rafter can span not the diagonal distance or actual length of the rafter.
