Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal.
Roof rafter size table.
Click the button to calculate the stock size needed for this job.
Surveyors span tables for designing roof rafters.
Input the rafter span on the flat eave overhang and pitch of the roof.
This calculator is to be used as an estimating tool only.
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.
For pitched roofs flat roofs and ceiling joists.
If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center.