Kiln-dried lumber and green lumber may look alike at first, but they behave very differently once they’re built into a project. The difference comes down to moisture. Freshly cut wood holds a lot of water, and how that water is removed affects how stable the board will be.
Green lumber is wood that hasn’t been dried much after cutting. It’s often easier to cut and nail, but it keeps losing moisture over time. As it dries, it shrinks and can twist, cup, or crack. That’s why green lumber is more common in rough framing, timber work and fencing, where small movement is less of a problem.
Kiln-dried lumber has been dried in a large oven called a kiln. Heat and airflow bring the moisture down to a set level in a controlled way. The result is a board that’s more stable, lighter, and less likely to shrink after it’s installed. Boards stamped “KD” or “KD-19” have been kiln-dried, with the number showing the maximum moisture content.
Choosing between the two depends on the project. Indoor framing, trim, cabinets, and furniture usually call for kiln-dried lumber, since movement can cause gaps, nail pops, or cracked finishes. For outdoor posts and rough work, green or air-dried wood may be fine.
Even dry lumber can pick up moisture from the air. Storing boards flat, off the ground, and out of the rain helps keep them straight. Letting them sit in the space where they’ll be used also helps them adjust.
Kiln-dried lumber costs more effort to produce, but it saves trouble later.
Builders in Los Angeles can find kiln-dried framing lumber and expert advice at Anawalt Lumber, family-owned since 1923.
