Abstract

Characterization and Hygrothermal Impact of Water Resistive Barriers on Mould Growth in Wood-Frame Wall Assemblies

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Abstract

Water-resistive barriers (WRBs) are vital components in building envelope systems, particularly in wood-frame buildings, where moisture-induced decay is a major durability concern. This study presents a detailed experimental characterization of three WRB membranes, quantifying key transport properties including vapor permeability, liquid diffusivity, moisture storage, and saturation content using high-precision gravimetric methods. The resulting moisture-dependent functions were integrated into hygrothermal simulations using DELPHIN, and mould growth risk was assessed via the VTT model under varying wall configurations and climates. Results show that while material properties such as vapor permeability and liquid diffusivity significantly influence moisture behavior, they alone do not guarantee moisture control. Wall design and climate conditions also play a critical role. In cold-wet conditions, some assemblies exceeded the ASHRAE 160 mould index threshold of 3.0, indicating risk of visible mould growth. These findings underscore the need for comprehensive evaluation of WRB performance, incorporating both material characterization and system-level context to support durable, mould-resistant buildings.

Keywords: Moisture control, Building envelope, WRB, Material properties, Hygrothermal simulation, Mould growth

How to Cite:

Yari, M. H., Esmizadeh, E., Riahinezhad, M., Wang, L. & Dragomirescu, E., (2025) “Characterization and Hygrothermal Impact of Water Resistive Barriers on Mould Growth in Wood-Frame Wall Assemblies”, UCL Open Environment 7(S1). doi: https://doi.org/10.14324/111.444/ucloe.icmb25.a31

Rights: Author, [2025]