I am researching deck construction. I read one article about how important the moisture content of the wood was. It was really more geared towards the deck boards – how they would shrink when they dried. But what about the moisture content of the framing lumber? If you build a deck out of pressure treated lumber that is really wet and notch the rim joists into the post and get a good, tight fit when it’s wet then won’t it dry and shrink, too? Then the width of the rim joist won’t completely fill the notched area of the post and your post is greatly weakened. Is this correct?

Should you only use kiln dried lumber for your decking?