ROOF TRUSSES
TRUSS COUNT
trusses = ceil(L × 12 ÷ spacing) + 1
ft
RESULT
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FILL IN ABOVE
Engineered design required — supplier sizes lumber and connections for span, snow, and dead loads. This calculator handles count only, not truss design or pricing.
About this calculator
This roof truss calculator estimates the number of prefabricated roof trusses needed for a residential or light commercial building, based on building length and spacing. Standard residential spacing is 24 inches on center; 16-inch spacing is used for heavier snow loads, longer spans, or to allow lighter top-chord lumber. The calculator returns common trusses for the field, gable end trusses for the two end walls, and the total piece count to order. Engineered trusses must be sized by the supplier for your specific span, snow load, and roof loads.