Abstract: In a wood curing kiln, a chamber is sealed to retain a negative pressure with respect to the ambient and for storing stacked lumber to be cured and having a concrete floor with embedded heating pipes for circulating heated water to heat the concrete floor to a temperature preventing condensation thereon, and with means for circulating heated air within the chamber and through the stacked lumber to remove moisture therefrom and with the chamber being constantly vented to remove moist air and maintain the negative pressure within the chamber. A tarp is suspended from the ceiling of the chamber above the stacked lumber to enable the tarp to be lowered to cover and seal the top of the stacked lumber so that the heated air flows across the top of the tarp and down into and through an end of the stacked lumber.