According to Build Green: Wood Can Last for Centuries, an obvious source of wood decay is wood that is wetted continuously by plumbing leaks. The leak itself is not always as obvious. Spillage behind a washing machine, leaks in caulk at the top of a bath tub, or plumbing leaks in a shower stall often go unnoticed for a long time. If so, they can lead to a serious decay problem in the floor and lower parts of interior walls. Annual inspections and minor home maintenance can prevent this type of problem.