Let s consider a basic gable wood roof framing design.
Lumber spans for roofs.
In areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot.
Live load is weight of furniture wind snow and more.
For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements.
2 are indicated below.
For example you can span a 1 grade no knots southern yellow pine a greater distance than a 2 grade with knots southern yellow pine.
Continuing on from part 3.
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.
Span calculator for wood joists and rafters also available for the android os.
The tables below give maximum spans for rafters and beams.
1 ft 0 3048 m.
Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no.
Dead load weight of structure and fixed loads 15 lbs ft 2.
The image below shows a cross section of our simple 12 x 13 house from the joist span tables section of this tutorial.
Here we have a wood framed gable roof.
1 psf lb f ft 2 47 88 n m 2.
The figures are based on quality materials.
Wood beam calculator american wood council website rafter and joist span faq.
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.