KD-HT (Kiln-Dried Heat-Treated)
Lumber that has been kiln-dried to 19% moisture content or less and heat-treated to a core temperature of 56°C (133°F) for 30 minutes to kill insects and pathogens. Required for international shipment under ISPM 15.
In Detail
KD-HT lumber is dimensionally more stable than green (S-GRN) lumber, with less shrinkage, warping, and checking after installation. The grade stamp shows "KD-HT" or "KD" with a moisture content indicator (MC15 or S-DRY). Most SPF lumber sold at retail is KD-HT. SYP may be sold green (S-GRN) or kiln-dried — verify the grade stamp before purchasing for critical applications.