Bracing prevents trusses from bending, twisting, or otherwise deforming. On bottom-chord-bearing trusses, the ends are tied together with 2x4 ledgers that also serve as a nailing base for the perimeter of the plywood deck (see illustration below). Underneath, 2x6 strongbacks laid on edge should run continuously through the webs of all the trusses at 10-ft. intervals (one run for a 20-ft. truss, two runs for longer trusses). The 2x6 serves the same purpose as bridging in a standard floor, distributing concentrated loads over a wider area.

The ends of bottom-chord-bearing trusses are designed to be tied together with 2x4 ledgers that also serve as a nailing base for the perimeter of the plywood deck. In addition, install horizontal 2x6 strongbacks at 10-ft. intervals to distribute loads and prevent twisting, which can loosen truss plates.
The ends of bottom-chord-bearing trusses are designed to be tied together with 2x4 ledgers that also serve as a nailing base for the perimeter of the plywood deck. In addition, install horizontal 2x6 strongbacks at 10-ft. intervals to distribute loads and prevent twisting, which can loosen truss plates.

For learn more about framing with floor trusses, visit the JLC Field Guide