Free Roof Truss Calculator — Count, Spacing & Cost (2026)

How to Use This Calculator

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

About This Material

Roof trusses are pre-engineered triangular wood assemblies designed to span the full width of the building without requiring interior load-bearing walls. Each truss is factory-built to a specific engineering design using 2x4 or 2x6 lumber connected with metal gusset plates. Common truss profiles include Fink (W-pattern, the most common), Howe, and scissors (for vaulted ceilings). Trusses must be ordered from a licensed truss manufacturer based on your building plans, and they typically have a 4 to 8 week lead time. Standard residential trusses are spaced 24 inches on center and can span 24 to 40 feet depending on design. Truss pricing depends on span and complexity — simple 24-foot span Fink trusses cost $75 to $150 each, while 40-foot spans or specialty profiles can cost $200 to $400 each. Delivery usually requires a flatbed truck, and installation requires a crane or boom truck for lifting trusses into position.

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.

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