I have removed most of the old cracked tile, but now I am to the floor of the shower. I have been using a sledgehammer so far, but the walls had some flex. (The tiles were installed on top of cement, so I broke out 1 1/2" of wall material.) The shower floor has an 8" raised edge made of wood on the outside coated with tar, and it looks like there is 2" of cement inside that, and then the old tiles. Do I keep going with the sledgehammer? I don't think I can tile over existing tile due to age, and may have to remove the wood framing after we determine if the wood is water damaged. Thanks for any tips!