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.
Safe spans for no 1 roof rafters.
Span calculator for wood joists and rafters available for the iphone.
Rafter spans can be extended slightly beyond what the rafter tables suggest when there is a cantelever extending beyond the supporting wall.
Patio roof maximum beam rafter spans.
Calculations determine the maximum spacing based on the material used rafter size and load the roof needs to hold so that the roof is safe and meets all building codes.
Simplified maximum span tables for selected visual and mechanical grades of southern pine lumber in sizes 2 4 thru 2 12.
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View joist rafter tables.
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.
2 are indicated below.
1 ft 0 3048 m.
Live load is weight of furniture wind snow and more.
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.
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.
This table is simply a sample and may not be valid for your region.
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.
Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no.
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.
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.
Sample maximum spans feet inches douglas fir or larch no 1 or no 2 with 31 3 psf of snow loading.
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.
1 psf lb f ft 2 47 88 n m 2.
