I'm trying to find out what's wrong with a leaking shower floor in the basement. Having eliminated all the surface possibilities, I removed the drain and hammered out the floor to examine the drain pipe. I dug down to where the pipe is, but I expected to see a liner here. Isn't this where the liner should be, tacked under the pipe mount (don't know what to call that flange)?
There's definitely a smooth surface here, so I'm at the division between a couple of different layers (i.e., base layer dried and hardened underneath top layer). Everything I've found about drain construction makes it sound like there should be some barrier at this point. I'm worried that the lack of a barrier right here might be the problem (meaning the whole shower's coming out).