Behavior of engineered wood materials under the effect of wetting and drying cycles

A test procedure to simulate and measure the actual behavior of solid and engineered wood products subjected to realistic cyclic moisture loading conditions was carried out at the Institute for Research in Construction (IRC), National Research Council Canada (NRC). The wetting and drying experiments on oriented strand board (OSB), showed that the rate of moisture absorption and the rate of drying for successive wetting and drying cycles are different from the rates of absorption and drying found on the initial cycle. The OSB samples showed continuous dimensional change in which it was observed that the thickness continued to increase over the test period. It was found that the increase in thickness is a nonlinear function of moisture content and time and the number of cycles. Sample size, board thickness and edge boundary conditions all have significant effect on the response of OSB materials to cyclic moisture changes.