Roof Truss Lateral Bracing

There are two separate types of bracing to be concerned about.

Roof truss lateral bracing.

If trusses are not designed with stabilizer see bcsi 1 for stabilizer spacing and diagonal cross bracing required. 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. 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. 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.

Certain truss members require bracing in order to carry the full design load. Use wooden 2x4 or prefabricated metal braces as short member temporary lateral restraints between the trusses. Permanent bracing listed on the truss design drawing for specific web members and permanent bracing for the roof or floor system. Purlins 24 oc are typical along with the bottom bracing shown.

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. Type of load important. When truss spacing exceeds 2 feet purlins are generally required to support roof sheathing. Diagonal bracing installed for the purpose of increasing the stability of the truss system during installation shall be installed on web members verticals whenever possible located at or near each row of bottom chord lateral restraints.

This condition generally applies when trusses are spaced at 2 feet. Diagonal braces are required at each end of a truss row and repeated every 10 truss spaces 20 maximum. Roof sheathing plywood osb provides effective lateral bracing when sheathing is nailed directly to top chords. Continuous lateral bracing or restraint is very important.

Flat coastal fringes fens airfields and moorland. 7 2 9 bracing for trussed rafter roofs trussed rafters shall be suitably braced to support applied loads and self weight without undue movement.