The torsional rigidity of wood members is necessary for predicting lateral torsional buckling of laterally unsupported beams, and is useful for estimating the stiffness of two-way floor systems and the natural frequency for wood floors. Current estimations of torsional rigidity of composite wood materials are based upon elastic constant ratios of solid wood. Recently published work has found differences in the elastic constant ratios of solid wood versus structural composite lumber (SCL) materials. These differences in elastic properties may indicate differences in torsional rigidity. Rectangular sections of solid-sawn lumber and various SCL materials were tested to determine values of torsional rigidity. Torsional rigidity of solid-sawn lumber was significantly different (
