How we worked it out
Updated as you change the numbers.
- Run = span ÷ 2 − half the ridge = 11.938 ft.
- Length = (run + overhang) × √(1 + (pitch ÷ 12)²).
Method and assumptions
The rafter is the hypotenuse of the run and the rise. Measuring along the top edge from the ridge plumb cut, add the overhang’s run before applying the pitch factor. Buy stock longer than the result for cuts.
Questions
How long are the rafters for a 24 ft span at 6/12 with a 12 in overhang?
About 14.46 ft, so 16 ft stock.
Sources
Method and figures checked on . Every worked answer on this page is covered by an automated test. Found a mistake? Tell us.