Moisture Damage in Hot-Humid Buildings: Drying Deficit, Envelope Moisture Response, Mold-Risk Assessment, and Building Adaptation

Moisture damage in buildings has traditionally been discussed primarily in relation to winter condensation in cold climates. In hot-humid regions, however, damage develops under different boundary conditions, including warm and humid outdoor air, frequent rainfall, air-conditioning operation, air leakage, and limited drying after wetting. Climate change is treated here as contextual background that can intensify these boundary conditions, not as the primary object of quantitative attribution. This structured narrative review synthesizes literature on climatic boundary conditions, envelope moisture response, moisture- and mold-risk assessment, microbial implications, and building adaptation. It is supplemented by illustrative climate-data analysis, global exposure mapping, and selected field examples; these components contextualize the proposed drying-deficit framework but do not constitute comprehensive validation or global risk prediction. Drying deficit is proposed as an interpretive framework for situations in which moisture supply, storage, and repeated wetting exceed available drying capacity over relevant time scales. The review identifies the need for assessment methods that account for cooling-driven gradients, airflow paths, material storage, microbial response, and occupant behavior. It also highlights adaptation strategies such as rain control, leakage reduction, vapor-open drying paths, humidity-controlled ventilation, dehumidification, moisture-tolerant materials, and integrated hygrothermal and microbial monitoring. The proposed framework requires further validation and should not be treated as a universal explanation for all moisture damage in hot-humid buildings.