Deep snow in British Columbia: survey implications for the National Building Code of Canada

This article presents an overview of results from the 1980–1992 survey of snow loads and densities on roofs in deep snow areas of British Columbia with particular emphasis on results from an extensive survey at the ski village on Mt. Washington, Vancouver Island, where the 30-year return ground snow load is 21 kPa. The article makes recommendations for the design of buildings in deep snow areas and, of particular importance to designers, shows for the first time that the National Building Code of Canada (NBCC) procedure for obtaining design snow loads works for such areas. It also shows that the density of roof snow at high loads is about 400 kg/m3 (one third higher than average NBCC values) and that NBCC recommended roof loads at elevations above the tree line may be excessive. The article also makes suggestions for the management of deep snow on roofs based to a great extent on experience from Mt. Washington.