Cement Backer Board on Cement Subfloor?

[scary_penguin]

I'm planning on tiling the entryway around the cutout door to my basement (about 3' x 6') and a hearth in front of a fireplace. (about

2' x 4'). Both are going to be ceramic tile, and are going to be surrounded by wall to wall carpet on 3 sides. Right now, the floor is an unfinished cement floor, and the carpeters are coming in a week or two, so I need to get moving on the tile.

After talking to a guy at the store, we agree that I probably need a backerboard under the tiles, so that the height is proportionate to the surrounding carpet. (Moderately thick pile on top of a 3/8" moisture resistant pad). So I bought some 1/4" Durock cement backer boards, and was getting ready to start slicing them up and putting them down, when I thought of some more questions.

1) Do I need to (i) tape the seams and/or (ii) put down some moisture membrane on the area by the door, or can I just seal my grout and figure that it's cement all the way down?

2) How should I attach the backer board to a concrete subfloor? Will thinset be enough to hold it in place, or should I mess with masonry bits and screws, and if I need to screw it down, what kind of bit and screw should I use?

3) Is there a good way to figure out if I've got the tile at the right height? Would I be happier with 0" of backerboard (i.e. none), or 1/2"?

Thanks, TM

[Colbyt]

I am not a tile pro just a DIY tile guy.

Thinset is not going to be enough to hold this stuff in place. And that is a lot of masonry screws.

You will need to float it of level if it has the tapered edges. Over concrete I doubt that tape is of any value.

My advice is to not bother. No one is going to really notice a half inch of difference. Your raw floor is stronger and more stable than what you are about to create.

Spend the money you are about to waste on some reason nice transition trim to cover the joint. The place to start looking would be where you are buying the carpet. A better deal may be available elsewhere but their installers may not want to install it if they don't get to sell it.

Colbyt

[wannabe]

My primary trade is installing tile.

don't use durock, you want the tile to feel flat with carpet when it is being walked on, not just if it looks level.

use a sealer/blocker on concrete.

use premium adhesive/thinset/mortar it even mixes creamier than cheapo bag.

after grout cures (2 weeks +,-) use a 7 - 10 year sealer, this will keep the grout easy to clean and fresh looking for years.

Happy Installing

[PipeDown]

Strictly speaking, you don't need backerboard, the tiles can be set directly on the concrete but unless you want a very thick bed of mortar, the cement board is the best material to use for a build up. It depends a lot on the thickness of the carpet and pad you plan to use

There are also metal beads for outside corners, edges and a ramp shape for floor transitions if you want to go that way.

As long as the concrete floor is in good condition, probably any thinset will hold it in place without nailing, it is just a small area (

[wannabe]

ever use a bucket of vynal glue on ceramic tile on concrete?

looks like it would never come up (not without a crowbar)

(its my secret weapon)