The old door to the deck had a cracked bottom plate and frame that would swell every winter making it very difficult to open.  This poor wood door took a beating by the weather every year in its southern exposure setting. The old door frame had a rotten custom-built threshold that I had to duplicate when I cut it out.  That's half the old threshold sitting on the deck off to the right. When I made the new one, I made sure to primer and paint the entire piece and caulk every little crevice, so no moisture should ever get in to swell the frame.