Parallel Chord Truss Calculator
A parallel chord truss has a top and bottom chord that run perfectly level and parallel to each other, connected by a web of diagonal and vertical members — the standard shape for engineered floor trusses and level structural framing. Enter your span below to size a parallel chord truss.
Size Your Parallel Chord Truss
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Estimates only. Actual costs vary by region, supplier, and site conditions.
Parallel Chord (Floor) Truss Design
Because both chords are level and the same length, a parallel chord truss carries load entirely through truss depth and web triangulation rather than through roof slope — deeper trusses span further, which is why floor trusses are typically 12" to 24" deep for residential spans.
Open-web parallel chord trusses are popular for floors because the open space between webs lets plumbing, ductwork, and electrical runs pass straight through the truss depth, avoiding the notching and drilling required with solid floor joists.
This calculator approximates board footage and cost using the same span-and-pitch geometry as a flat roof truss; for an exact floor truss design, a manufacturer will size chord and web members from your actual floor live load (typically 40 psf for residential floors) and span.
Frequently Asked Questions
What is a parallel chord truss used for?
Parallel chord trusses are most commonly used as engineered floor trusses, and occasionally as flat structural roof trusses, because their level top and bottom chords make an ideal surface for flooring or roofing above and open web space for utilities below.
How deep does a floor truss need to be for a given span?
Floor truss depth generally scales with span — light residential spans often use 12"-16" deep trusses, while longer spans need 18"-24" or deeper trusses. Confirm exact depth with a truss manufacturer using your actual floor load.