Lumber that is dried by being exposed to air, rather than an oven or kiln.

Lumber that has been piled in yards or sheds for any length of time. For the United States as a whole, the minimum moisture content of thoroughly air dried lumber is 12 to 15 percent and the average is somewhat higher. In the South, air dried lumber may be no lower than 19 percent.

Solid wood which has been air dried without kiln drying.

is lumber that is stored in yards or sheds for any length of time.

Lumber that was dried, usually outside, to an equilibrium moisture content with the air it was exposed to.

Boards that have dried naturally by stacking them in the open air, as shown above and right. Air flows between the boards, allowing the moisture in the wood to evaporate. Air drying can take as long as one year per inch of board thickness. In all but the driest regions, moisture content rarely falls below 12 to 20 percent without additional drying indoors.