Calculation of sound transmission parameters for wood-frame and mass timber assemblies

While much of it is proprietary, a significant amount of the data from sound transmission tests performed on mass timber assemblies has been shared in the public domain. Previous efforts at using this data to develop empirical models for estimating single-number ratings of floor assemblies have been limited in scope and have not always yielded accurate results. In order to provide an additional means of demonstrating compliance with code requirements, the American Wood Council (AWC) has developed calculation-based analysis approaches for deriving STC and IIC ratings for assemblies constructed with wood-based framing and mass timber. As required by the International Building Code (IBC), these analysis procedures are based on comparisons of data from floor/ceiling assemblies having STC and IIC ratings as determined by the test procedures set forth in ASTM E90 and ASTM E492, respectively. The models presented in this report can be used to estimate STC and IIC ratings of: a.) light-frame floor/ceiling assemblies framed with either sawn lumber, wood I-joists, or wood trusses and b) mass timber floor/ceiling assemblies constructed with either cross-laminated timber (CLT), dowel-laminated timber (DLT), or veneer-based mass timber. Descriptions of the models are provided. Validation and application of the models are also discussed.