Construction
Truss Count Calculator
Count roof trusses along a building length at a given spacing, including both end trusses.
The result is the number of trusses needed along the building length, including one at each end.
Formula
Number of trusses = (building length divided by truss spacing) plus one, rounded up, so both ends have a truss.
How it works
Enter the building length the trusses run along and their centre-to-centre spacing. The count includes an end truss at each side. Truss design, bracing and connections must come from the truss manufacturer or a structural design, not from this count.
Worked example
For example, a 10 m building with 0.6 m truss spacing gives 10 divided by 0.6, which is 16.67, plus 1, which is 17.67, rounded up to 18 trusses.
FAQs
What spacing is typical?
Six hundred millimetres is common in many houses, but the design may specify something else.
Does this include gable trusses?
End trusses are included in the count, but special gable or dropped trusses must be confirmed with the supplier.
Can I change spacing to use fewer trusses?
Only if the truss design allows it. Spacing affects loads on each truss and on the roof covering.
Rough estimate only — consult a licensed professional for structural work before building.
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