AbstractThe purpose of this study was to determine the dimensional stability of oriented strand boards (OSBs) with the core layer made of fine wood chips when the boards were exposed to air of variable relative humidity (30%, 65%, and 85%). The share of fine wood chips, intended for the particleboard core layer or originating from comminution of unrefined particleboards, accounted for 50% or 100% of the core layer mass. This study revealed much greater changes in the length of the board's shorter axis, regardless of the type of fine wood chips in the core layer. These changes increased with an increasing share of this type of chips in the core layer. More pronounced changes in thickness were observed for particleboards containing 50% of the fine chips. The research also showed that the relative changes in linear dimensions were slightly smaller in OSBs containing 50% of wood chips from the comminution of unrefined particleboards than in the boards with a core layer made from wood chips designed for this purpose.