Modeling of wind-driven rain absorption ratio of building exterior finishing materials based on field measurements

Wind-driven rain (WDR) constitutes a significant source of moisture for building facades, which poses considerable challenges to both the thermal insulation performance and long-term durability of walls. Prior studies have contributed significantly to the understanding of fluid behavior and moisture response of WDR upon impacting walls. However, the quantification of absorbed rainwater by the wall remains elusive. To address this gap, this study focuses on comprehending the dynamic WDR absorption behavior of various exterior finishing materials. Specifically, nine types of finishing materials were selected as research objects and conducted field measurements. The findings reveal that WDR absorption ratio is influenced by physical parameters of materials, surface waterproofing and the cumulative WDR. Leveraging multiple regression fittings, we established an empirical WDR absorption ratio calculation mode. This model serves as a valuable reference for determining building simulation parameters regarding dynamic moisture boundary conditions on the exterior surfaces of walls. By providing empirical insights into WDR absorption, our research contributes to a more comprehensive understanding of moisture behavior in building envelopes, thereby aiding in the development of effective strategies for enhancing building performance and durability.