chapter  4
24 Pages

- Moisture Properties

Wood was designed by nature over millions of years to perform in a wet environment. The wood structure is formed in a water-saturated environment in the living tree and the water in the living tree keeps the wood elastic and able to withstand environmental strain such as high wind loads. We cut down a tree, dry the wood, and mainly use it in its dry state. But, wood in use remains a hygroscopic resource. Wood’s dimensions, mechanical, elastic, and thermal properties depend on the moisture content. Wood is also anisotropic which means that its properties vary according to its growing direction [longitudinal (vertical or length direction), tangential (parallel to annual growth rings), and radial (perpendicular to the annual growth rings)]. The mechanical properties depend very much on both moisture content and growing direction.