Moisture content and seasoning

Lumber is strong in both tension and compression, and is elastic. However, the moisture content of wood can vary, typically from 5 per cent to more than 20 per cent. The greater the moisture content, the less strong is the lumber. As a result, wood with 28–30 per cent moisture content may be only two-thirds the strength of the same wood at 12 per cent moisture content. When moisture is reduced, the lumber shrinks and in consequence shows fewer tendencies to warp, split or shake, and has greater dimensional stability. Seasoned and dried lumber will be lighter and stronger. The sap in lumber is a food for fungi and parasites, so if it is removed the wood is less attractive to fungus and parasites. For example, reduction ...

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