Frequently, structural wood sheathing or rigid ceiling sheathing is directly attached to the top or bottom chord of a floor or roof truss is used to provide permanent lateral restraint and diagonal bracing. However, when assemblies are specified for fire or sound rating, the assembly may call out either resilient channel, furring channel, or hat channel at a given on center spacing. If a single layer of gypsum is specified in the assembly, frequently the metal channel would be directly attached to the bottom chord of the truss and the gypsum is then attached to the metal channel.

The question addressed by this research report is how the lateral restraint and diagonal bracing requirements may be met when the gypsum sheathing is not directly attached to the bottom chord.