Hygrothermal resiliency of wood-frame wall assemblies and climate change
Date
2026
Authors
Croyle, Benjamin
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Abstract
Moisture-related deterioration in wood-frame building envelopes is a major concern in cold and wet climates and is expected to intensify under increasingly extreme conditions driven by climate change. Existing hygrothermal performance metrics do not adequately capture the resilience of building envelopes to prolonged and extreme moisture loading. This thesis presents a comprehensive hygrothermal analysis of the resilience of wood-frame building envelopes under extreme climates. Hygrothermal simulations were conducted in WUFI Pro V6.7 to evaluate brick, stucco, composite wood, and engineered wood clad wall assemblies in six Canadian climates. Across two chapters, the wall assemblies were analyzed under increasing wind-driven rain leakage and projected future climates. Two indices were developed to assess performance: a Robustness Index, based on peak moisture content to represent maximum loss of functionality, and a Resilience Index, which evaluates the capacity for moisture dissipation and recovery over time relative to a critical threshold. These metrics were validated against the mould growth index, a widely used indicator of biodeterioration risk. The new indices were shown to be sensitive to both cladding properties and climate characteristics. In particular, the Resilience Index responded negatively in assemblies with high capillary uptake claddings in low drying potential climates. The Robustness Index was more sensitive to large amounts of concentrated wind-driven rain. The impact of climate change on the two new indices was found to be dependent on both location and cladding type. Under the tested conditions, the robustness and resilience indices demonstrated greater sensitivity to performance changes under low biodeterioration risk than the mould growth index. This work provides a functionality-based framework for evaluating and comparing building envelope designs, supporting the development of more climate-adaptive wall assemblies under both current and future environmental conditions.
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Keywords
Hygrothermal simulation, Wood-frame wall assemblies, Moisture risk, Robustness index, Resilience index, Wind-driven rain, Climate change