What is kiln dried lumber?

December 12, 2012 Print Friendly and PDF


A dry kiln is a chamber that is designed to control the environmental conditions of heat, humidity and airflow during the drying process for lumber. The conditions used in a kiln usually exceed those found in the natural environment and vary depending on the species being dried, thickness of the lumber, initial moisture content of the lumber and the desired final moisture content. Most hardwood lumber is dried at temperatures between 90-180oF and some softwood lumber, such as southern yellow pine may be dried at temperatures exceeding 220 oF. The final moisture content of lumber that is kiln dried varies based on the final use of the material. Wood that will be used on interior of a home is usually dried to a 6-8% moisture content. Wood that will be used outdoors is usually dried to approximately 12% moisture content. Most softwood construction lumber is dried to 15-19% depending on the grading specifications. While the moisture contents discussed above are typical for kiln dried material, the statement that the material is kiln dried does not indicate what the moisture content actually is. It is very important when purchasing or using kiln dried lumber to know what the moisture content of the lumber is.

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