Wood-based composites are primary building materials in low-rise residential structures in the U.S. Wood composites are susceptible to moisture degradation if exposed to high levels of moisture in service.  Moisture durability is routinely assessed with accelerated weathering (AW) procedures. Applying AW results to wood composites exposed to adverse conditions in service, however, is hindered by the severity of AW conditions and small specimen sizes evaluated.  This project addressed two key components necessary to further knowledge of wood composite moisture durability, which were (1) the influence of specimen size on AW results at the small-scale and (2) moisture durability of structural-size specimens.

This presentation will discuss the results and implications of the findings. In general, specimen size did not influence mechanical performance of laminated veneer lumber (LVL), oriented strand board (OSB), or plywood at the small-scale. AW and outdoor exposure of wood composite I-joists resulted in loss of bending strength and shift in failure mode. When full-size shear walls were constructed with weathered OSB sheathing, statistically significant reductions in yield strength, shear capacity and energy dissipation were realized. In addition, a numerical model was developed to predict moisture transport in OSB and plywood under cyclic changes in relative humidity, which was validated experimentally.

Daniel Way is pursuing a PhD in Wood Science.  Shortly after defending, Danny will begin working for Boise Cascade (Medford, OR) and be responsible for developing, planning, and managing engineering projects. Danny is excited to explore southern Oregon and work in the wood-based composites industry.