Get a single rafter length from run, pitch and overhang, with the ridge thickness taken out.
How it works
Run × 12, less half the ridge thickness, × the slope multiplier gives the top edge length. The tail is added the same way.
Before you order
- Mark the plumb cut with a framing square set to your pitch.
- Keep the birdsmouth notch to a third of the rafter depth.
- Cut one pattern rafter and test it before running the rest.
Common questions
What is a slope multiplier?
The square root of 1 plus pitch over 12, squared. A 6/12 roof is 1.118.
Why subtract the ridge board?
The rafter stops at the ridge face, half of its thickness short of center.