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Abstract
Transient conditions arising from sun exposure of absorptive claddings after being wetted by rain impose significant hygrothermal load on wood-frame walls. In this paper, we show that moisture conditions generated by the inward drive of water vapor increase the risk of mold growth and durability issues in susceptible components of the wall assembly. We present a comprehensive set of one-dimensional hygrothermal simulations on solar-driven moisture diffusion in wood-frame walls with brick cladding and oriented strand board (OSB) sheathing. Sensitivity analysis identifies key material transport properties with critical effect on moisture dynamics in wood-frame assemblies, such as the vapor permeance of the weather resistive barrier and ventilation of the air gap behind the brick cladding. Informed by the results of the simulations, full-scale test walls are designed, and their moisture performance evaluated in a one-of-a-kind analytical chamber, the CARWASh, equipped to generate controlled indoor and outdoor environments with realistic wind-driven rain and sun exposures. A grid of sensors monitors the relative humidity, temperature, and moisture content at different heights and depths of the wall assembly to capture critical spatial and temporal variations. These
in-situ measurement results are intended to be compared with simulated values for validation. The results overall are intended to assist building designers in their efforts to minimize the risk of moisture accumulation in wall assemblies across different U.S. climates.
Citation
Farkas, Natalia; Glass, Samuel V.; Zelinka, Samuel L. 2025. Hygrothermal Modeling and Laboratory Tests of Solar-Driven Moisture Diffusion in Wood-Frame Walls with Absorptive Claddings. In: Proceedings Buildings XVI Conference, Thermal Performance of the Exterior Envelopes of Whole Buildings. Clearwater Beach, FL. Dec. 8-11 2025. Peachtree Corners, GA: ASHRAE: 1-9.
