Reliability analysis of roof sheathing panels on wood-frame houses under wind loads in Canadian cities

A reliability analysis of roof sheathing panels was performed to assess the current minimum requirements specified in the National Building Code of Canada (NBCC). The present analysis considers the variations in the annual, hourly-mean wind speeds in cities across Canada, the external wind pressures due to roof shape, roof slope, eave height and upstream terrain, the internal wind pressures, for the range of fasteners typical of current construction practice. It was found that the use of 6d (51 mm) common nails with 300 mm spacing on intermediate supports, which is the minimum requirement of NBCC, is not adequate for many regions of the country. It was found that relatively small differences in fastener size result in large differences in roof sheathing performance. Recommendations for revisions to NBCC are made, which involve using 8d (63 mm) nails, with 150 mm spacing on intermediate supports.