Assessing Moisture Resilience in Residential External Wall Assemblies under Standard and Elevated Moisture Loads

This is the authors' abstract. We don't add key points for this paper.

Mould affects approximately 30% of housing worldwide and one in three buildings in Australia, with substantial health and economic consequences. Current moisture-risk compliance pathways rely on hygrothermal simulations under prescribed boundary conditions, yet wall performance under elevated moisture loads remains underexplored. This study investigates the hygrothermal behaviour of common Australian residential external wall systems under standard and increased moisture conditions. Transient one-dimensional simulations were conducted in accordance with DA07 and ASHRAE 160 criteria, alongside four non-standard scenarios representing condensation and minor leakage events. Results indicate that wall systems performing satisfactorily under standard conditions may not remain moisture resilient under elevated loads. Ventilated cavities can reduce moisture risk when airflow and drainage are effective, while insulated brick veneer walls may exhibit high mould susceptibility and limited drying capacity when inadequately detailed. These findings support the development of more robust moisture-safe design practices, risk assessment approaches, and future regulatory reform and policy.