Roof Truss Lateral Bracing

Certain truss members require bracing in order to carry the full design load.

Roof truss lateral bracing.

For the purposes of this chapter the guidance and use of standard trussed rafter bracing does not apply to homes on or near exposed sites e g. Set each truss after the first with its top chord temporary lateral restraint aligned with the ground bracing. The stabilizer must be supplemented with diagonal bracing in the roof and ceiling planes and cross bracing in the web plane at required intervals shown on the individual truss design drawing tdd. There are two separate types of bracing to be concerned about.

Use wooden 2x4 or prefabricated metal braces as short member temporary lateral restraints between the trusses. When truss spacing exceeds 2 feet purlins are generally required to support roof sheathing. This condition generally applies when trusses are spaced at 2 feet. Flat coastal fringes fens airfields and moorland.

To strengthen the roof system truss clustering cross bracing and wind bracing is recommended at both end of the buildings and every 20 for longer span buildings. Diagonal braces are required at each end of a truss row and repeated every 10 truss spaces 20 maximum. If trusses are not designed with stabilizer see bcsi 1 for stabilizer spacing and diagonal cross bracing required. Continuous lateral bracing or restraint is very important.

7 2 9 bracing for trussed rafter roofs trussed rafters shall be suitably braced to support applied loads and self weight without undue movement. Type of load important. Individual truss member lateral restraint and diagonal bracing the truss designer identifies the location of required individual truss member i e web top chord or bottom chord restraint bracing. Roof sheathing plywood osb provides effective lateral bracing when sheathing is nailed directly to top chords.

Purlins 24 oc are typical along with the bottom bracing shown. Permanent bracing listed on the truss design drawing for specific web members and permanent bracing for the roof or floor system.