Given the remarkable growth of engineered wood products (EWP) in recent years, and considering industry’s desire to maximise product recovery and value, Forintek undertook a literature search and mill visits to investigate drying practices in Eastern Canada regarding major engineered products (MSR lumber, finger-jointed studs, wood I-joists, glued-laminated beams), and how such practices affect manufacturing processes.
The study revealed that most plants were equipped with on-line moisture detectors to reject undesirable pieces, but, with a few exceptions, little effort was made to adapt drying specifications to EWP requirements. The lumber used was generally dried to the same standards as commodity lumber (19 per cent maximum) even though high moisture contents caused pieces to be downgraded by MSR machines, and moisture content differentials between adjoining pieces was thought to be responsible for some poor finger-joints in structural studs. Based on the experience of some mills, questions were raised as to the effect of high-temperature drying on mechanical properties.
However, attitudes were observed to be changing to a client focus as operations became better established, especially in integrated plants. Recommendations made to support improved returns through drying quality include investigation of 1) the effect of moisture content differentials on finger-joints, 2) optimum moisture contents and drying schedules for MSR production, and 3) the effect of high-temperature drying on I-beam flange material performance.