High Exposure Category
Buildings in the high exposure category require additional features to provide the required resistance to lateral loads. Nineteen locations identified in NBC Appendix C fall into this category for wind and 33 for earthquake exposure. For wind, affected locations are in Newfoundland, Quebec, Alberta, Nunavut and the Northwest Territories. Most of the locations affected by earthquake risk are in the coastal region of British Columbia and four in the Lower St. Lawrence region of Quebec.
The NBC includes prescriptive solutions that call for the use of strong portions of walls called braced wall panels. Requirements for location, spacing, dimensions, fasteners and construction materials must be met, and these solutions are subject to limitations based on building height and whether the construction is comprised of heavy materials such as concrete roof tiles or concrete topping on floors. In addition, buildings in the high exposure category must also address concerns such as foundation anchorage, sheathing thickness, and sheathing and drywall fastener lengths and spacings. Lumber sheathing, if used, must be installed diagonally on both walls and roofs. Obtaining an engineered design is also an option.
Source : Canada Mortgage and Housing Corporation (CMHC)