Internal moisture evolution in timbers exposed to ambient conditions following kiln drying

Abstract

This study aimed to investigate the changes of internal moisture content distribution within hem-fir timbers after kiln drying while exposed to two different local outdoors seasonal conditions. Timbers were dried to three different target moisture contents (12, 17, and 22 %) and thereafter, they were conditioned outdoors in two diverse seasonal coastal environments, namely, cold-wet wintertime and warm-dry summertime. Moisture contents at quarter-point and the center in depth were continuously monitored for a period of 3 weeks. The results showed that no significant moisture content reductions took place during the cold-wet season equalization, while moisture content differences were regularly reduced regardless of seasonal conditions. In addition, below 2.5 % differential moisture content, moisture movement between at quarter-point and the center slowed down regardless of seasonal condition or current moisture content level. At high drying target moisture content of 22 %, moisture content values both at quarter-point and the center remained constant after 2 weeks at moisture content difference value of 2.5 %, and no further drying or no further moisture content equalization were observed after that point.