This document is design example of Wood Diaphragm on Reinforced CMU Shearwalls. It uses a school gymnasium located in Surrey, British Columbia as the example. The plan dimensions are 20m x 30m, with a total building height of 7m. The walls are 190 mm reinforced CMU, and the roof diaphragm consists of plywood sheathing and SPF framing members. The roof plan is shown in Figure 1. The site is Seismic Class ‘C’. Wind, snow and seismic data specific to the project location are taken from the latest version of the National Building Code (2010). Roof dead load is assumed to be 0.9 kPa and the wall weight is 2.89 kPa. The weight of non-structural items including mechanical equipment has not been included in this example for simplicity.