This document is a design example of Wood Diaphragm Using Envelope Method. it uses a typical one-storey commercial building located in Vancouver, BC as the example. The plan dimensions are 30.5 m x 12.2 m (100’ x 40’), with a building height of 5 m. The walls are woodbased shearwalls, with a wood diaphragm roof and a steel moment frame at the storefront. The roof plan is shown in Figure 1. The site is Seismic Class ‘C’. Wind, snow and seismic figures specific to the project location are taken from the current version of the British Columbia Building Code (2012). Roof dead load is assumed to be 1.0 kPa and the wall weight is 0.5 kPa. The weight of nonstructural items including mechanical equipment and the storefront façade has not been included in this example for simplicity.