Pitched Roof Rafter Spans

Surveyors span tables for designing roof rafters.

Pitched roof rafter spans.

The pitch and span of your roof will dictate how long of a rafter you ll need use maximum span calculator to help you find your rafter size. For roofs that will experience heavy snow or wind and will span the same distance use 2 6 rafters. For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements. Continuing on from part 3.

For roofs that won t experience heavy snow loads a gable roof can span up to 22 with 2 4 rafters. Click the button to calculate the stock size needed for this job. Surveyors and structural engineers utilise data from tables below to help calculate the correct size strength and centres of roof timbers for the required spans and loadings. Floor beam span tables of residential structural design we will now look at roof rafter and beam design.

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. Pitched roof timber sizes. Maximum rafter spans for a patio roof in areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot. Anything beyond that you are looking at using 2x6s for most sheds.

Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal. Here we have a wood framed gable roof. Our roof rafter calculator tools are handy for calculating the number of rafters needed rafter length calculator lineal feet of rafter board feed in ridge and sub facia and the total board feet in the roof. Input the rafter span on the flat eave overhang and pitch of the roof.

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. Maximum clear span of rafters in metres for roof pitches of between 15. This calculator is to be used as an estimating tool only. The image below shows a cross section of our simple 12 x 13 house from the joist span tables section of this tutorial.

Let s consider a basic gable wood roof framing design. All the figures are based on roofing tiles or slates laid on timber laths over sarking felt. Span calculator for wood joists and rafters available for the iphone. The following tables give details of the allowable spans and spacing for some of the more common timber sizes used in traditional roofing construction.

If you look at the rafter span chart you ll notice that 2x4s can be used for rafters on spans up to 11. For pitched roofs flat roofs and ceiling joists.