Wood Truss Sizer

You're picking a truss for a roof or floor span, but span alone does not describe what it carries. Spacing sets the tributary width; loading sets the weight on that strip. Watch those relationships before choosing the depth of the section.

Longer spans increase global bending demand. Closer spacing reduces the load carried by each truss. A deeper section can reduce the ideal force couple needed to resist the same moment, but member sizes, connector plates, deflection and openings still belong to a complete truss design.

Span, spacing and depth change the load carried by one truss.

24 ft span · 16 in spacing

55 psf over a 16 in tributary strip gives 73.3 lb/ft. Section depth is assumed, not selected from a capacity table.

73.3

lb/ft

Load per truss

5.3

kip·ft

Global moment

2.6

kip

Ideal force couple

Parallel-chord illustration: uniform load, simple supports, q = area load × spacing; M = qL²/8. M/depth is an ideal force couple, not a member or connector capacity.

Drag the clear span endpoint on the drawing. Arrow keys work too.