Assessment of Moisture Performance of National Building Code Canada Compliant Wall Assemblies under Climate Change

Abstract

Due to climate change, higher temperatures and rainfalls are expected to happen in some areas of Canada, which might increase the climate loads on buildings and lead to premature degradation of moisture-sensitive materials in wall assemblies. To investigate potential durability issues in three cities across Canada (Ottawa, Vancouver and Calgary), code-compliant wood-frame walls with two types of claddings, stucco and brick, were simulated using Delphin 5.9. Two different climate data sets, historical and future when a global warming of 3.5o C is expected to be reached were used. The hygrothermal performance in terms of mold growth risk was analysed with respect to cladding types, considering air leakage. All the three cities are similarly warmer in the future. However, wind-driven rain (WDR) is higher in Vancouver than in Ottawa and Calgary. With brick cladding the relative humidity is kept below the threshold for mould development only in Ottawa and Calgary. With stucco in future, while Ottawa shows greater mould indices than historical, Calgary shows opposite behavior. The results suggest that the risk of mould growth due to air leakage may decrease in the future.