I have the same boat and had the same issue. The repair was all done from the bottom and wasn't the end of the world price wise. Good luck! Also, I replaced the couch and had a filler pad made with folding legs.It all looks good to me except swim platform. I would want to know where exactly was the elevated moisture on the platform and how much of platform is elevated. It may not be much but I am sure you will check it thoroughly. Good luck. JC