Timber Truss Design Calculator
King-post truss member forces, rafter sizing, and bottom chord tension from span, rise, and loading.
Inputs
ft
ft
psf
ft
in
in
Results
Rafter axial force
6,923 lbs
Bottom chord tension
2,880 lbs
King post tension3,840 lbs
Horizontal thrust2,880 lbs
Rafter compression capacity48,000 lbs
Rafter utilization ratio0.14
Min bottom chord size2.1 in
Min king post size2.4 in
Pitch angle33.7°
Pitch (x:12)8:12
Rafter length14.42 ft
Total load on truss7,680 lbs
How to Use This Calculator
- Enter Truss span, Truss rise, and Total roof load.
- Set Truss spacing, Rafter width, and Rafter depth.
- Adjust Wood species as needed.
- Review Rafter axial force (lbs) and Bottom chord tension (lbs).
- Use King post tension (lbs) and Horizontal thrust (lbs) to inform your decision.
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