Here in the Pacific Northwest, or the Pacific Northwet as a friend of mine called it, we inspectors see many decks that have some decay present. If the structural lumber is pressure treated then often that will be okay. However the flat surface wood decking boards will frequently have a soft/decayed surface that can even be unsafe. I have known people to step on a deck and go right through -- one leg hanging lower than another.

The flat surfaces are the most exposed and, when rain hits, the water will soak into the wood. And, over time, that causes rot. Carefully cleaning as required, and treating the deck surface, can help prolong the decking boards. When you see vertical cracks in the decking, rain will soak in and that will cause rot quite rapidly. When you see moss and algae, that is a sign that rot will not be far behind.

Speaking of rot not being too far behind. Here are a couple photos that are typical.

Wood will rot at moisture levels of twenty percent and above so, needless to say, keeping exterior wood from rotting in the northwest takes careful planning and maintenance.

Thanks for stopping by,

Steven L. Smith