# ceramic tile walls



## Nestor_Kelebay (Jun 17, 2008)

Ponch37300:

I'll let the tilers in here handle the question of whether or not it's a good idea to prime a wall before tiling it. I'd be more inclinded to tile over the skim coat of joint compound you intend to put on. Priming the wall before tiling introduces one more ambiguity into any potential problems. If the primer doesn't adhere well to the wall, and tiles start to come loose, is the problem in the skim coat, in the primer, or in the mastic or thin set, etc. If you tile over the skim coat, there's one less potential source of problems.

Yes, if it's a relatively dry area where water seldom splashes on the wall, then tiling over drywall with mastic or thin set is fine.

The reason why a cement type tile backer board is needed in a wet area like a shower is because plaster and drywall and greenboard will disintegrate if they get wet repeatedly, so a small crack that allows water into the wall turns into a bigger and bigger crack as the strength of the wall behind the tile deteriorates and the tiles gradually become loose. The weakening wall results in more cracked grout, and you have a snowball rolling downhill.

Also, you don't ever want to tile over wood because wood swells and shrinks with seasonal changes in it's moisture content caused by changes in humidity and temperature. Ceramic tiles and grout simply don't have the elasticity to accomodate dimensional changes in a wood substrate. So, if you tile over wood, there's a good chance that the grout lines will crack. The expansion and contraction of plywood is smaller than the same species of lumber, but it's never a good idea to tile over any wood.

Drywall is acceptible in a dry area simply because it's dimensionally stable, and in a dry area repeated wetting won't be an issue.


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## angus242 (May 1, 2008)

You can tile over the drywall without issue....as long as it's not some kind of heavy stone.
However, I wouldn't use drywall compound as a base. Drywall compound emulsifies when wet. If you need to repair a few sections, that's OK but don't skim the entire area. If you have to retape the seams, that's OK too. Just use one coat of compound for the tape. I don't see any benefit to priming the walls first. Use a modified thinset for the tile. While mastic is technically acceptable, for 4' of tile just use a typically portland cement modified thinset that you mix yourself. It will be cheaper and hold better. Trowel the thinset on the walls in a horizontal pattern. This will help keep the tiles from wanting to slip down. Think of it like tile holding on a pole (vertical) :no: or hold to a beam (horizontal) :yes:


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## ponch37300 (Nov 27, 2007)

Thanks for the replies. The walls were primed before the wall paper so after removing it I'm left with primed drywall in most areas. After reading the responses I will be using modified thinset. Is there any problems with going over the primed walls? Should I rough them up at all? Thanks again.


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## angus242 (May 1, 2008)

ponch37300 said:


> Is there any problems with going over the primed walls? Should I rough them up at all? Thanks again.


No problems going over the primer. I was just saying no need to add it if it wasn't there already. I successfully tile (back splashes) over painted walls often.


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## ponch37300 (Nov 27, 2007)

Thanks Angus.


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## mpj111 (Apr 29, 2008)

In replying to your question, i would like to add my question too.
I am going to tile My new bathroom, . Dry (green jib) walls done and need to tile. Do I need to paint with water proofing paint. I shopped around and water proofing paints are available . If i do water proofing paint, will it give good adhesive to my tile and glue or make it weak in the long run

I have shower cubical and no water get in to the wall. But I belive moisture deposits on the wall.
Like to here your advice.


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## angus242 (May 1, 2008)

mpj111 said:


> In replying to your question, i would like to add my question too.
> I am going to tile My new bathroom, . Dry (green jib) walls done and need to tile. Do I need to paint with water proofing paint. I shopped around and water proofing paints are available . If i do water proofing paint, will it give good adhesive to my tile and glue or make it weak in the long run
> 
> I have shower cubical and no water get in to the wall. But I belive moisture deposits on the wall.
> Like to here your advice.



You do not have to use waterproof paint. While grout is not waterproof, your concern would only be valid in an actual wet location, like the shower itself. 
Steam likes to rise in a bathroom so make sure you had adequate ventilation and you won't have a problem with excessive moisture.
As for the wallboard, if you have a lot of drywall compound in the area(s) you're going to tile, use a primer made for sealing fresh drywall. If there's minimum compound, you can tile right over it. 

That is, of course, as long as you're NOT using natural stone.


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