Moisture content in lumber

What is moisture content of lumber?

The amount of moisture in wood is often expressed as a percentage of the weight of the wood when the oven-drying method is used. When a tree is still growing, the tree may have more moisture in it than ovendry wood fiber, resulting in moisture contents greater than 100%. As wood is cut and exposed to air, the moisture dries from the wood. In a sawmill, this process can be expedited by running the rough lumber through a kiln process, exposing it to elevated temperatures to aid the drying process. Southern Pine lumber can be gradestamped as KD19 when it has been dried in a kiln to a maximum moisture content of 19%. This generally means that the average moisture content of the lumber will be close to 15%, with some pieces somewhat drier and some pieces somewhat wetter.

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