Its one of those, "A friend's friend" is tiling the bathroom. After completing the shower & removing the old tile (installed in the 60's), the existing walls are of course, covered w/the old glue. The "friend" instructed me to (using a chilsel) to remove all the existing old glue and plaster. Basically to take it down to the studded/screened/concrete surface. This seemed pretty excessive, so I thought, "Why can't we cover up the old gunk w/ the same backerboard that was used in the shower? Wouldn't we then have a flat, clean, durable surface in which to lay the tile?" It was pointed out that the backerboard was too thick, therefore the tiles wouldn't butt properly, ie - leaving a larger/fatter/thicker grout line where the shower tile and the wall tile met.
Although I'm extremely grateful for the reduced cost in labor (a friend's friend), it took me nearly 20 minutes to remove a 2" x 3" area. At that rate, it will be 2012 before I get my bathroom finished.
I appreciate your input.