Pitched Roof Rafter Span Table

Floor beam span tables of residential structural design we will now look at roof rafter and beam design.

Pitched roof rafter span table.

Surveyors span tables for designing roof rafters. For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements. Also available for the android os. Click here for structural design calculations.

3265 45 3220mm total span less ridge thickness 3220 2 1610mm horizontal span each rafter will cover and before meeting the ridge now when we turn to the 30 page in the rafter ready reckoner and when looking up the common rafter lengths one of the things it tells us is. The tables below give maximum spans for rafters and beams. Here we have a wood framed gable roof. Span calculator for wood joists and rafters also available for the android os.

Let s consider a basic gable wood roof framing design. If you look at the rafter span chart you ll notice that 2x4s can be used for rafters on spans up to 11. Anything beyond that you are looking at using 2x6s for most sheds. This will give us the span for each individual roof rafter.

Straight line interpolation shall be permitted for intermediate spans and design values. In areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot. Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal. These span tables assume installation of at least three joists or rafters that are spaced not more than 24 on center.

For pitched roofs flat roofs and ceiling joists. The calculated spans assume fully supported members properly sheathed and nailed on the top edge of the joist or rafter. 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. 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.

The image below shows a cross section of our simple 12 x 13 house from the joist span tables section of this tutorial. For example in the rafter span table below the highlighted cell in the 40 live load table indicates that 2 x 8 southern yellow pine joists that have a grade of 2 that are spaced 24 apart can have a maximum span of 10 feet 3 inches 10 3 if designing for a live load of 40 lbs ft 2. The figures are based on quality materials.