A job Im trying to come up with a uninvasive workaround for. Shower wall is boxed with small access panel mostly impeded by toilet. So nigh impossible to see what is happening down there without removing whole bath. Doubt bath has adjustable feet. When bath is used the seam between bath and showerwalls open up a quarter inch with weight. Think floorboads under bath must have play. Water end up coming through basement light fixture. Goal is to find waterproofing solution without decon. Any caulk just wont stretch. Thought about a marine product like epoxy resin but could snap plastic with added weight. Plus look terrible. Need a membrane I can shove in there and / or aesthetically pleasing run off. Its a lath & plaster craftsman so a creaky old house. Its a client I like.