Span A Slope Roof With Lumber

Consult local building codes for snow load capacity and reference the span tables for joists and rafters published by the american wood council awc as a general rule roofs that have a high human occupancy rate should be framed with rafters every 16.

Span a slope roof with lumber.

The tables below give maximum spans for rafters and beams. Floor beam span tables of residential structural design we will now look at roof rafter and beam design. There are also factors such as deflection elasticity and wood species that come in to play. 1 psf lb f ft 2 47 88 n m 2.

Span calculator for wood joists and rafters also available for the android os. The figures are based on quality materials. 1 ft 0 3048 m. Dead load weight of structure and fixed loads 15 lbs ft 2.

Continuing on from part 3. For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements. 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. The image below shows a cross section of our simple 12 x 13 house from the joist span tables section of this tutorial.

The thickness of plywood used for roof decking depends on the roof slope the spacing of rafters and the weight of other material to be put over the decking as well as the design load the. These numbers are for roofs supporting light loads of 20 pounds for square foot. Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no. Live load is weight of furniture wind snow and more.

Flat the most economical flat truss for a roof is provided when the depth of the truss in inches is approximately equal to 7 of the span in inches. 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. Difference in slope between the top and bottom chords is at least 3 12 or the bottom chord pitch is no more than half the top chord pitch. Roof rafter span use this table to determine the maximum lengths of roof rafters based on species and grade of lumber spacing dimensions load and slope.

Here we have a wood framed gable roof. Also available for the android os. 2 are indicated below. Can span up to 13 4.

An spf roof at the same spacing and lumber size will span 11. Floor joist span use this table to determine the maximum lengths of floor joists based on species of lumber joist spacing and joist size. In areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot.