Concrete floor, plaster wall, concrete backboard: Thinset(s)?

[Laine MacTague]

I am tiling a bathroom with concrete backerboard around the tub/shower area, plaster over drywall in the rest of the bathroom, and a concrete floor. The wall tiles (all the shower/tub & ~ 3' of the rest of the walls) are going to get 3x6" ceramic, and the floor is getting 1x2" tiles adhered to 12x12" fiberglass "mats". I have a bunch of modified thinset for this, which the tile store says is sufficient for all 3 surfaces. Agree? Disagree?

Furthermore: I can't use DITRA under the floor tile because the 1X2s are too small. Should I worry a lot about not having that layer?

And another thing: The shower wall i took down was moisture barrier / drywall / plaster / mortar / thinset / tile. It was all dry as a bone and intact. I am planning on moisture barrier (leatherback) / concrete backerboard / thinset / tile. Is that suffient?


Thanks muchly,
Laine

[bbcamp]

Welcome, Laine!

MNodified thinset will be fine on all three surfaces.

You don't need Ditra for your concrete floor, unless you have come cracks. Do you?

I don't know what "leatherback" is (with the possible exception of sun-damaged skin), but if it is a moisture barrier, not an air infiltration membrane, then it's OK. Otherwise, you plans are good.

[Laine MacTague]

Thanks for getting back so quick, bbcamp!

No cracks, and as it is a fairly old slab now, I don't really expect any.

Leatherback is a brand for a moisture barrier often used on roofs.

I sanded the paint on the plaster - is that sufficient prep for the thinset there?

[bbcamp]

Leatherback sounds good.

Floor prep: Clean off any adhesive or paint using only mechanical means, no solvents.

Plaster wall prep: Clean surface with TSP based cleaner, then lightly scuff the gloss off the paint.

[Laine MacTague]

Oh yeah - I have no special corner tiles - for where the wall and floor meet. Does it matter which I lay first - the floor or walls?

Thanks for your help - I think I'm all out of questions!

OOps, one more... just found this in archives:
I want to put ceramic tile in a bathroom with textured, painted walls. I would like to know what special prep is required if any.
John Bridge
01-20-01, 06:48 PM
Darrel,
Not a good idea. If what you are talking about is a wainscot (half wall), you might consider adding another layer of sheetrock or cement backer board.
If it's going to be a wet area (shower), we need to talk.
John

Is he in disagreement with you about tiling over the walls, then?

[Laine MacTague]

I tested the plaster walls with a screwdriver; although the paint has come off in a couple places, they seem quite sound. No crumbling to speak of when I push at them with the screwdriver. So - am I ok to tile over this stuff?