What is the standard roof truss spacing?

24" on center is the most common residential truss spacing. It reduces truss count and cost. Some designs use 16" OC for heavier loads or longer spans.

Can I reuse old trusses?

Generally no. Engineered trusses are designed for specific spans and loads. Reusing trusses without engineer approval is not safe or code compliant.

Roof Truss Calculator

Calculate the number of roof trusses needed based on roof length and on-center spacing.

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Enter Your Measurements

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How to Use This Calculator

1Measure the roof length (ridge length) in feet.
2Select your truss spacing (24" OC is standard for residential).
3Click Calculate.

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About This Material

Roof trusses are engineered wood assemblies that span the full width of the building without interior bearing walls. They are factory-built to custom specifications and must be ordered from a truss manufacturer.

Installation Tips

•Order trusses 4–6 weeks in advance — lead times can be long.
•Have a crane or boom truck on site for lifting.
•Brace trusses laterally during installation — they are unstable until sheathed.
•Follow the truss placement diagram from the manufacturer.

Common Mistakes to Avoid

Not ordering gable-end trusses (different from standard trusses).
Insufficient temporary bracing during installation — trusses can collapse.
Placing trusses on bearing walls only — do not load non-bearing partitions.