A typical lifespan of natural wood decking is 8-10 years with regular cleaning and maintenance, while composite decking can last as long as 20 years with very little maintenance. Regardless of the building materials used, docks will absolutely need to be maintained. Boat docks are subjected to harsh conditions because they are exposed to constant water and sun exposure.  Additionally, the seasonal temperature changes of both the water and the air can breed rot and decay of your dock.