About the garage and barn roof truss
Garage and barn roofs usually span 20 to 40 feet without interior posts, so the trusses carry more load and need heavier chords, deeper webs and good bracing.
When to choose it
Use this page for detached garages, pole barns, shops and agricultural buildings. Wider spans often need engineered trusses with 2×6 chords or larger.
How to use this calculator
- Enter the building span and the length along the ridge.
- Pick the pitch (or switch to an exact angle) and set the eave overhang.
- Choose spacing, material, snow and wind loads. Results update as you type.
Start with the default 30 ft span, then change the span to your building width and watch the truss count and weight update.
Practical tips
Check door header locations before fixing truss positions, and allow for snow drifting near taller adjoining roofs. The load results here help you size the order, but they do not replace a stamped drawing.
Need a different figure? Try the span calculator, the cost calculator or compare options on the all truss types page.