At the request of the Council of Forest Industries, a simplified (hand-calculation) design method has been proposed for estimating the ultimate shear capacity and load-deflection response of wood-framed and panel-sheathed diaphragms, by Forintek's Wood Engineering Department. In its current form, the simplified code design approach can predict ultimate shear capacity for a wide range of (blocked) diaphragm constructions, sheathed with panels ranging from 7.5 mm (3/8") to 18.5 mm (3/4") in thickness, with a 22% coefficient of variation. This is comparable to the 21% variability exhibited by the current Canadian diaphragm design method, and not alarmingly larger than the 16% shown by the more detailed APA design method. Indeed, for the three high-shear diaphragms sheathed by 18.5 mm (3/8") Douglas-fir plywood panels, the proposed simplified design method yielded shear prediction errors of only 0%, 1% and 6%. Furthermore, simplified functions were also able to provide good estimates of diaphragms failure mechanisms, and their load-deflection patterns, as measured in earlier verification tests. Predictions from the simplified model need to be experimentally verified for high shear capacity diaphragms sheathed in thick panels fastened to glulam frames by large diameter nails; before its possible introduction to the Canadian wood design code.