Abstract: An improved kiln for seasoning lumber. The kiln includes an air treatment and circulating assembly adjacent the top wall. The air treatment and circulating assembly includes a series of fan assemblies for circulating air to the lumber stacked within said chamber and means for heating air within said chamber. An exhaust venting system located on the downstream side of the airflow from the lumber stack and on the upstream side of the air treatment and circulating assembly is operable to exhaust moisture-ladened wet air prior to the air passing through the air treatment and circulating system. The kiln also includes an intake air vent located downstream of the air flow from the air treatment and circulating assembly and upstream of the stacked lumber which adds additional outside air to make up that portion of air which is exhausted through the exhaust venting system.