Severe wood decay in timber occurs when the moisture content exceeds what percentage?

Severe wood decay in timber typically occurs when the moisture content exceeds 20 percent. At this level, wood becomes highly susceptible to fungal growth, which leads to decay. When moisture content is at or below this threshold, most types of wood are less likely to be affected by decay-causing organisms.

The 20 percent threshold is significant because it is generally recognized in the field of pest control and wood preservation as the critical point where conditions become favorable for the development of wood-destroying fungi. Maintaining moisture levels below this percentage is essential in construction and pest management to prevent rot and increase the longevity of wooden structures.