Am not getting the vapor barrier thing, at all?
OK, redoing my shower and using an acrylic shower pan. And I read a million posts about the vapor barrier. So now I have the following questions:
1) I just do not understand this water flowing down behind the cement board and back into the tub? How does it get throught the tile, grout, thinset, backerboard in the first place. And when it "flows" down the vapor barrier, how does it get into the shower base? I thought the gap between the tile and shower base is caulked? Wouldn't water fill up behind the wall? And how much water flows down this system during a shower...gallons, teaspoon full, ???
2) What is the correct vapor barrier process. After it is installed to the walls, do you drape it over the tile flange? And if so, how can this be done because I thought the gap between the backerboard and the top of the shower pan flange should be caulked...how can it be caulked with a piece of plastic sticking out or over the top of it? From literature, after this gap is caulked, you tile over the backerboard and let the tile hang over the flange until it is about 1/8" above the shower base. And then this gap gets caulked. Now we have 2 (!!!) caulked joints preventing water from getting back into the shower pan.
3) What is better...a poly vapor barrier, or redguard over the backerboard?
4) Isn't a vapor barrier really for condensation of a hot tiled wall and a cooler internal wall? Versus a mechanism for water flower? I am relating this to the term vapor barrier of house insulation.