Green Horizons

Green lumber to be air-dried must have good air circulation under the stack as well as between each layer of boards in the pile. To prevent unnecessary warping the stack must also be properly supported. Lastly, roofing tin placed over the top helps keep rain and snow from excessive re-wetting.

Once Dave has cut his lumber, he stacks the green boards to begin the drying process. Fresh-cut lumber can start out with a moisture content above 70 percent (measured on a dry weight basis); way too high for any practical use. Properly air-dried lumber will have a moisture content around 20 percent; good for use around the farm for or in unheated structures, but still too green for use in heated buildings (like your home). For use in these latter situations, the lumber must be further dried in a kiln to reduce the final moisture content to below 8 percent.

Two excellent publications on drying lumber are:

University of Missouri Guide G5550: Air-drying Hardwood Lumber.
Available online at http://extension.missouri.edu/p/G5550

Virginia Tech Guide 42-030: Design and Operation of a Solar-Heated Dry Kiln.
Available online at http://pubs.ext.vt.edu/420/420-030/420-030.html