Tiling a bathroom.

[N1K]

Ok, so I'm finally getting around to the last piece of my remodel, the bathroom. I decided to keep the cast-iron tub and just get it re-finished.

So the first thing I'm going to do is the floor.

In order to make the height of the floor match the rest of the tile on the first floor that I laid a year or two ago I would need the 5/16 cement board, mortar and tile....

The problem is that I'll be tiling over old tile (the little 1x1 floor tile) The subfloor is PERFECT. (1" of poured cement) but here's my problem:

I can't screw the cement board down. It obviously won't anchor in the tile/cement subfloor...

here's a diagram

Easiest would be to just put miriatic acid down on the floor to etch the tile, thinset, and lay the tile. but that wouldleave me 1/4" to 5/16" short.

I'm worried that if I put down thin-set UNDER the cemet board to anchor it to the old tile, then I'll be to HIGH after putting thinset over the board and tiling.

Any ideas????

I thought maybe there was some adhesive that I could put under the cement board to bond it to the old tile that would be a relatively thin layer. So that if I put adhesive, cement board, thin-set and tile, it would pretty much be the same height as the tile already laid in the hallway.

Otherwise I thought maybe I should just put a sloping layer of mortar down first to make the new tile surface level (at least where it meets) the new tile I laid last year. let that set, and then just tile over that mortar 'shim' and then the existing old tile and not use the cement board at all.

I guess what I'm looking for is.. Is there anyway to bond that cement board to the existing tile floor that would not make a significant change in the height?

OR if I can't bond the cement board down, what options do I have to get the whole thing level?

[KA]

I've had good luck with glue by calling 3M's adhesives department and speaking to a tech.

Their phone service requires some degree of patience but the number is 800-362-3550.

Good Luck

[CBRXX]

I assume those existing tiles are solid, you just want to update.

You could probably etch the tile like you said, but I would add an extra step and hit it with a coarse grit sanding disc to give it some "tooth".

You could just bed the cement board into a layer of thinset, or maybe you could use liquid nails type adhesive (which you can get in a gallon cans) and a V-notch trowel. Either way, just throw some weights on it while it sets.

That is a small height difference. Maybe easiest to just use a threshold between the 2 different floors. You could use Oak, or Marble, Aluminum, etc. depending on the tiles and other decor.

I also prefer the latex modified thinset. It has a better stick and flex to it, I think, just costs a bit more.

Steve

[Steve]

If that picture is accurate your thinset looks cupped

I've never been one to tile over existing tile. It is a P.I.T.A but I like starting fresh. Tiling is pretty easy and cheap to do yourself for the record.. I rented a tile saw from Home Depot a few years ago for @$45/day, found that to be quite worth it. I had to do a kitchen floor, two bathroom floors, countertops, shower, linen cabinet tops, and some other shit. I may go with Granite this next time...

[N1K]

You could probably etch the tile like you said, but I would add an extra step and hit it with a coarse grit sanding disc to give it some "tooth".

Yeah, in retrospect, that would have been very little effort, and more assured better grip.

I etched and laid tile right over. I am actually really pleased with how well it held. I tested a portion that was under the area the toilet would cover, and it bonded REALLY well.

Its about 1/8 inch lower then the other tile. So not bad... I'm not going to do anything. Just grout the seam and leave it.

I'll have to post pictures.

[CBRXX]

Glad it worked well. That thinset really does stick. Definitely post pics.

Steve

[StPeteXX]

Pics ????

Rich