Uncovering Future Mold Risk in Existing Residential Walls with Climate Change

This paper examines the vulnerability of wood-framed residential building envelopes to mold growth under projected future climate conditions, specifically elevated temperatures and humidity, a topic that is rarely addressed in the climate resilience literature. Residential exterior walls designed with interior insulation and vapor-retarding membranes may prove inadequate in future conditions. This study combined hygrothermal simulation and mold growth computation using morphed future weather data to analyze archetypal walls from two construction eras (1990s–2000s and present) in three US cities: New York City, Philadelphia, and Washington, DC. The results show substantial increases in mold’s prevalence under future climate scenarios for historical code-compliant walls, with even greater risk in walls with highly impermeable vapor barriers. Contemporary code-compliant walls showed no increased risk of mold. This framework for assessing future hygrothermal risks in building envelopes suggests a potentially widespread resilience problem. It underscores the need for further research, especially given the vast inventory of existing wood-frame buildings from earlier eras.