I am in the process of redoing my upstairs bathroom. I would like to tile the bathroom floor. I have a tile-redi shower pan for the shower floor.
Q1: Do I need to put a moisture barrier over the wood floor before placing the tile-redi shower pan.
Q2: Before I tile the bathroom floor, how thick of cement board do I need to put down 1/4" or 1/2" for support and do I need to put a moisture barrier over or under the cement board?
Best Answer
No. The water leaking would then be expected to sit under shower based and on top of the moisture barrier? This might help diffuse an issue for a couple weeks but you would never know and might have a bigger issue.
What is your expectation here? If you put down lets say, a plastic sheeting, under backerboard... Well it will have screw holes everywhere and will leak. If you want your entire flooring waterproof like a big shower, then treat it like a shower and use something like a kerdi membrane or a paint on rubber membrane after your backerboard but before thinset. I have done both in bathrooms but most of the time neither. It depends on the importance of what is located below the bathroom. I personally install 1/2" durarock on bathroom floors. I lay out the backer so that the seams don't match the subfloor and also I try not to screw in the backer to the joists. If you had a 1" subfloor I could see going with 1/4" but this is hardly ever the case.