The data generated in this project will be used to develop damage functions for hygrothermal models designed to predict the performance of wall systems in a variety of climates. In the absence of these data, the building science community has used inappropriate data from laboratory tests never intended for this purpose, mostly on European wood species. Changes in building codes, mainly related to energy conservation, may have resulted in reduced ability of wood wall systems to tolerate moisture ingress caused by poor design and construction. While efforts are under way to improve design and construction (see Decision Aids for Durable Wood Construction), research is also needed in improved moisture control strategies for wall systems.