INPLANE HYGROSCOPIC EXPANSION OF PLYWOOD AND ORIENTED STRANDBOARD

The longitudinal, free hygroscopic expansion coefficients and the elas tic recovery after constrained in-plane swelling were experimentally d etermined for commercial plywood and oriented strandboard (OSB) struct ural panels. Preconditioned specimens were exposed to high relative hu midity (RH) at room temperature. The moisture content changes and dime nsional changes were used to calculate the in-plane hygroscopic expans ion coefficients (alpha) and the elastic component of recovery (alpha' ). These results are inputs for analytical models used to estimate dim ensional stability of the structural panels in changing RH conditions. The experimental procedure and the measuring techniques are described . Results are comparable to those reported in the literature.