Modeling Approaches for Moisture Transport in Brick Masonry Walls

Understanding moisture transport in masonry walls is critical for ensuring the durability, energy efficiency, and long-term performance of building envelopes, particularly under environmental stressors such as rising damp and wind-driven rain. This study investigates moisture transport in brick masonry walls considering the role of bond arrangements and the presence of external rendering layers. A combination of detailed micro-modelling and homogenized macro-modelling strategies was employed to simulate moisture transport across two wall configurations, namely an unrendered wall and a rendered wall with exterior and interior finishing layers. Simplified homogenization approaches, based on volume-weighted averaging and in-series and in-parallel schemes, were applied to estimate effective material properties. Numerical simulations conducted in COMSOL Multiphysics illustrate the influence of internal morphology and external rendering on moisture accumulation and transport rates. Comparative assessments between micro- and macro-models demonstrate that while homogenized models capture the overall moisture front progression, they may overestimate ingress rates in rendered configurations due to unaccounted interfacial effects. The findings highlight the impact of anisotropic transport behavior and emphasize the need for further refinement of simplified modelling strategies, particularly through the incorporation of interface hydraulic resistances. These findings contribute to the development of efficient modelling strategies that balance accuracy and computational cost, supporting improved predictions of moisture-related phenomena in both modern and historic building envelopes.