Kiln-Dried Lumber

Kiln-dried lumber is dried in a large, climate-controlled chamber under carefully managed heat, humidity, and airflow, rather than left to air-dry naturally over months or years in stickered stacks. It's dramatically faster -- days to weeks instead of a year or more per inch of thickness for air-drying -- and produces more consistent, predictable moisture content across a whole batch, which is why the overwhelming majority of commercially sold lumber, both softwood framing stock and hardwood, is kiln-dried rather than air-dried.

Dried too aggressively, though, a kiln run can introduce its own defects -- case hardening and honeycombing are both specifically kiln-drying risks, not something air-drying tends to produce, since air-drying's much slower pace gives the wood time to equalize internally as it dries.