Decay happens to players that want to settle their own base. It destroys out anything made of wood over time such as boxes, walls, structures, stairs, and any upgrades done to the wood building system.
Decay is indicated by a lighter shading (almost creme) on the wooden surface. In order to repair an item suffering from decay you will need 1 plank for foundations, walls, stairs (any major wood structures). You will need 1 log to repair storage crates.