Hydro Ban or Redgard (and insulation bonus question!)
First post, I've been lurking for a while and finally registered and got done with some lengthy searches.
We're doing a remodel in the bath, and I wanted opinions on the use of waterproofing materials to use over the Hardibacker. I want to do things right, and the differences in opinion on these two products seem to be at best, very great.
I like the idea that the Hydro Ban is not a vapor barrier, as I could use poly/felt to put a barrier over the wall studs. On the flip side, it's twice the price of the Redgard which some seem to say will do the same job. In my case I'll only need a couple of gallons (above tub tile only) to I'd rather eat the extra money if needed.
Does use of Hydro Ban actually require using their thinset for the tile, or will other brands of thinset work and adhere just as well?
The above leads to my second question. The home is split level, with the bath being the "split" and the first thing on the second level. Essentially the long side of the tub faces my downstairs attic, with only the studs between the two.
I want to increase the insulation between the tub wall and attic to minimize temperature swings and drafts. I'm assuming if I use the Redgard on the wall that I have to use a vapor barrier free insulation to do this to avoid the "moisture sandwich" situation. But if I use the Hydro Ban and a felt/poly barrier, could I use an insulation with a vapor barrier? They would essentially be a single vapor barrier consisting of two back to back materials, which in my mind would be similar to adding two layers of poly or felt rather than one. Is my thinking backwards in this regard?