We want to build a tub apron in front of our existing tub (to make the front look somewhat built-in) which will then be tiled with the same tile as the floor and walls. First, we need suggestions on what products to use to build this to make sure it is sturdy (to hold the tile) and then once it is built what should we use in the space along the new tub apron and the tub to make sure it is waterproof before we tile it?

I recently installed a new jacuzzi bathtub in my bathroom and I am having a recurring problem with a slow leak from the drain. The leak is coming from the 90 degree waste elbow directly under the tub drain (the part that the brass waste flange screws down into from the tub). The leak is seemingly coming from a seam in the waste elbow, which is ABS. I replaced the original elbow, thinking that I had cracked it during a somewhat rough installation. However, the new elbow also leaks from the same exact spot on the seam. It only leaks when the tub is full, not when the drain is open. I am certain that the leak is not coming from the seal between the gasket and the tub bottom. The leak is very slow (maybe one drop every 60 - 90 seconds), but I have an old tin ceiling below that I don't want to damage. Is it possible that I am overtightening the drain flange? I tightened only until it was snug and could not be comfortably turned anymore. I am using thread tape on the male flange threads and plumber's putty under the lip of the flange...could that have anything to do with it? I have my third elbow on order and am tired of trying to make the drain on my $2,000.00 tub leak-proof with a $2.00 part. Any advice would be appreciated.