Comment: There was a gap between floor and the patio door. That allowed water to seep in and go to the end joist. You can view it here - https://docs.google.com/presentation/d/1L-D3LecJczjtTh_uSC6WAYwWeeSnRdjnAQX3rWrCNFA/edit This came up as an issue during a house inspection, and I am looking at getting it fixed as soon as possible.