Rafter Length
Rafter length from span, pitch, overhang.
Example
You enter
- Horizontal span (ft) 12
- Pitch (rise per 12) 6
- Overhang (ft) 1
You get
- Multiplier 1.118
- Rafter length 14.534 ft
Details, formula, and sources
Rafter length L = sqrt(run² + rise²) plus tail and ridge plumb cuts. Birdsmouth depth limited to 1/3 rafter depth per IRC 2021 §R802.5.
IRC 2021 (International Residential Code). §R802.5.
Free read-only access at codes.iccsafe.org.
Estimate. AHJ and licensed structural engineer govern.
Field names used by the API: horizontal_span_ft, pitch_rise_per_12, overhang_ft, multiplier, rafter_length_ft
- Heel-cut depth limit ≤ 1/3 of rafter depthIRC 2021 §R802.5