Durability of wood

The durability of wood depends on various factors, such as the species of wood, the environment, and the design of the structure.


 * Natural Durability: The natural durability of a wood species is defined as its inherent resistance to wood-destroying agents such as fungi and insects . Different woods have different natural resistance to attack from destructive organisms such as wood-decaying fungi and wood-destroying insects. The Timber Durability chart contains five classes of timber, with each class determining how long each timber listed will last . The classification of natural durability is generally based on the heartwood's resistance to wood-decaying fungi in contact with the ground.


 * Heartwood vs. Sapwood: The durability assessment is only based on the tree's heartwood and not its sapwood . Only the heartwood, due to its extractives, has any appreciable degree of durability; in nearly all instances, sapwood should be considered perishable.


 * Design and Environment: Effective design counts for any structural material, including wood. With appropriate design, many wood products and species resist high humidity and chemicals and conditions that adversely affect other materials . Wood can absorb and release moisture and is resistant to many chemicals and conditions that adversely affect steel and concrete, such as corrosive salts, dilute acids, industrial stack gases, sea air, and extreme climate variances. When designed with local climate impacts, wood buildings can last centuries.


 * Durability Classes: There are five different classes of timber durability, ranging from class five to class one, where class five is considered not durable and class one is considered very durable. The classification of the natural durability of heartwood for wood species is in line with SS-EN 350, and durability is divided into five classes.