The foam panels were conditioned for 1 week at approximately 53% relative humidity (RH) using a saturated salt solution of Mg(NO3)2 according to standard methods (E104-85, ASTM, 1985). Some samples were also conditioned at different humidities to determine the effect of MC on mechanical properties. These samples were enclosed in sealed chambers that contained anhydrous CaSO4 (0% RH), or saturated salt solutions of CH3COOK (23% RH), Mg(NO3)2 (53% RH), NaCl (75% RH) or K2SO4 (97% RH). The final MC of conditioned panels was measured using a moisture analyzer (Model HR73 Halogen Moisture Analyzer, Mettler-Toledo, Switzerland).