Permanent Bracing for Wood Trusses: Why a Building in Snow Country Cannot Survive without It

Section 2303.4.1.2 of the International Building Code requires the installation of permanent bracing on pre-engineered wood trusses to: maintain truss spacing, resist lateral loads, and prevent buckling of individual truss members. To meet this requirement, all three planes within the truss, the top chord, bottom chord, and web member, must be adequately braced as outlined in chapter three of the Building Component Safety Information (BCSI) Guide. In regions with heavy snow loads, bracing to prevent web member buckling becomes a critical, and easily neglected, component within a building's structural system. This paper provides a review of permanent bracing requirements for wood trusses, illustrates a case study of the strength of an individual truss member where the strength is reduced by over 80% when bracing is either improperly installed or missing, and it discusses some of the indicators structural inspectors can look for to ensure their roof is properly braced while helping the building owner answer the question: "When should I shovel my roof?"