Tiling over old tile would explain the weird thickness. I had an inspection done earlier today and he didn't have any concerns with leakage or anything like that. It is a condominium so I don't know how much of the plumbing would be my responsibility, but I definitely will look into it. If I'm ripping everything out I may as well get a new tub!

TFW: If we were to DIY, I'd just be trying to remove the tiles (which are already falling off), clean up the underbed (whatever it is), and lay a small stretch of new, uncracked tiles that will be functional until we remodel the bathroom in full. Cat: I agree, I think the shower was likely improperly done in this bathroom by the previous owner. I have been hoping that molding/rotting wouldn't extend throughout the whole shower, but that's certainly a fear....

Who was in your house while you were gone? Why would they be using a strong acid like a metal cleaner, or a strong base like drain cleaner? The guests owe you the new counter! #bringsophieback https://www.gardenweb.com/discussions/5513253/bring-sophie-back#23104977  https://help.houzz.com/s/profile-support?language=en_US 

Sorry about the delayed update- much contractor drama at our end. Anyway, so we bought the TCNA handbook and educated ourselves (thanks AJCN, such a useful resource). We both take the day off from work and are driving to meet with GC when he calls and cancels (a tree toppled over on his property), says he will get back to us to reschedule shortly. Radio silence for the rest of the day. At this point we assume he is going to quit, so we figure the best strategy is to get what we can for our $. He is also working on a few additional things in the townhouse, so we decided to not let him work on the shower until he comes up with a satisfactory plan but let him finish the other stuff. In the meantime his painter who still showed up lets slip that he is not our GCs regular guy, this is his first time subcontracting with him and that the tile in the shower was not laid by GC. DH looks up GCs license and finds a city permit has been issued around the same time our work started for a complete building demo and rebuild. I suspect he is trying to wing things with our project (or delegate to his flunkies) since he has bigger fish to fry. Anyway, surprise surprise he actually shows up today morning! DH is at work so I am hesitant to discuss shower waterproofing technicalities solo. We come to the mutual decision that he is going to finsh the other work so we can move in, and then fix the shower. To his credit, he admits that the tile job is botched by his guy, but still insists shower pans on concrete subfloors do not need waterproofing. The two items that are remaining for him to complete are: grouting the kitchen backsplash reinstalling tile around the master bathroom tub flange. The plumbing for the tub was done by his plumber (again not his regular guy). I want 2 since I can grout a backsplash and 2 seems more critical to making the place liveable. This is where things go further south. Continuing in a separate post since I have pictures.