Open AccessThis study investigated the effect of the relative humidity (RH) and density of unidirectional oriented strand board (OSB) on parallel, perpendicular and through-the-thickness elastic modulus (E1, E2 and E3) and interlaminar shear modulus (G13 and G23). The relationships between these parameters and density were determined on unidirectional OSB panels with a flat density profile. The target densities were: 550 kg/m3, 700 kg/m3 and 850 kg/m3. Two RH levels at a constant temperature of 20°C were used to determine relationships between OSB mechanical properties and moisture content (MC). The analysis of variance (ANOVA) indicated that only density had a significant effect on the mechanical properties considered. Even though the effect of RH was not significant, a trend could be observed. Oriented strand board E1, E2, E3, G13 and G23, increased with an increase in density and decreased with an increase in RH. Finally, a regression procedure was used to determine the linear or quadratic equation necessary to predict the mechanical properties of the OSB panels as a function of density. A positive correlation was observed between the unidirectional OSB properties considered and density. These data will support the modeling of the hygromechanical behaviour of the OSB used as component in wood composite constructions.