Ok so I am just about to start tiling (tomorrow hopefully) my newly constructed bathroom shower/tub. I have put up concrete board. I was told by a manager at Home Hardware to use mastic in the shower for the tile because it is much easier to use, etc. etc. I just had Mike Holmes on in the background and heard him say never to use Mastic in wet areas. So I jumped online quick to read up on it and saw a few blogs on here saying never to use Mastic. Two questions:
A) If it is Mastic that is meant for wet areas is that ok or should I use dry un modified thinset?
B) I have already used the Mastic over the joints in the concrete board. Can I now change to thinset or will it not adhere where the mastic is?
I'm annoyed because I already spent $50 on the Mastic but I want this done right.