Birdsmouth Cut Roofing Calculator
Birdsmouth plumb and seat cuts for roofing rafters from pitch and overhang, with the rafter length.
Compare Your Options And Get Clear Answers
Birdsmouth plumb and seat cuts for roofing rafters from pitch and overhang, with the rafter length.
Birdsmouth Cut Roofing Estimator
Enter your numbers below for an instant estimate.
How It Works
Key concepts behind this calculator
Enter Values
Fill in each field with your own numbers.
Calculate
Results update as you change the inputs.
Review
Read the breakdown and the explanation.
Adjust
Change values to compare scenarios.
Birdsmouth Quick Guide
Typical values for reference.
| Rise | Span ft | Overhang in | Rafter ft |
|---|---|---|---|
| 4 | 24 | 12 | 13.70 ft |
| 7 | 24 | 12 | 15.05 ft |
| 9 | 24 | 12 | 16.25 ft |
| 12 | 24 | 12 | 18.38 ft |
| Rule of Thumb | Check inputs | Use as a guide | Round sensibly |
Birdsmouth Cut Roofing Calculator FAQ
Answers to common questions about this calculator.
Run times the square root of 1 plus rise over 12 squared.
The vertical side of the notch.
Length = run x sqrt(1 + (rise/12)^2).
It is an estimate based on the inputs you enter. Check real quotes, labels or official guidance for important decisions.