Roof Rafter Size Table

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.

Roof rafter size table.

It is always better to have a large rafter rather than be concerned with a sagging roof. Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal. This calculator is to be used as an estimating tool only. If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center.

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. Input the rafter span on the flat eave overhang and pitch of the roof. 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.