Tiling over a painted bathroom wall.

[suds]

Hello

New house that was built late last year, and we moved in back in June. My bathroom is a wet bathroom, and by that I mean it has a tiled floor with drainage. The problem is the tiling on the walls only goes up about 10 inches. The rest of the wall is painted sheetrock / drywall.

I want to tile the wall about 5 feet high , and should be able to withstand water being sprayed / hosed on the walls without letting any of it pass through the joints to the drywall. Can some link me to good online sources on how to do this?

Do I need to sand all the paint off before I affix the tiles?
Do I need to apply a primer before laying on the tile adhesive?
Do I need to cover the wall with a vapor barrier before applying tile adhesive or a primer?
What kind of adhesive do I use for tile, that is waterproof? Is it thinset?
For the grouting, what product do I use and do I need to seal the grout lines ? If so what kind of sealer?

Thanks

 

[Jamesplumbing06]

Umm. Around here I usually tell people. I dunno when tile guys become plumbers or vice versa but here that’s a huge misconception. You might have faster luck asking a tile forum. Good luck.

 

[Mr_David]

https://www.houserepairtalk.com/

 

[FishScreener]

Fine Homebuilding magazine, has a series of books, “For Pro’s by Pro’s”, and there are a couple of good books on installing tile in that series.

They do a good job of explaining how to do a good job, and how to select materials. They won’t make you a tile guy, but they will get you to the point you can make informed choices about whether to do it, and how to if you want to try it.

Since your existing walls are most likely just plain drywall, you might have to install one of the waterproof membranes first.

 

[Mikey]

I'm just finishing my 2nd shower remodel, this one a wet-room, using the Schluter Kerdi system. Pricey but it works; regular drywall specifically allowed for their membrane substrate, and recommended by several on-line experts. I'd be tempted to scuff up the paint before applying the thinset used to attach the membrane, especially if it's enamel, but their thinset sticks petty well to anything.

 

[Diehard]

I'm just finishing my 2nd shower remodel, this one a wet-room, using the Schluter Kerdi system. Pricey but it works; regular drywall specifically allowed for their membrane substrate, and recommended by several on-line experts. I'd be tempted to scuff up the paint before applying the thinset used to attach the membrane, especially if it's enamel, but their thinset sticks petty well to anything.

I had never heard of that. Looks pretty good in the video.

 

[PlumbGate]

Isn't this the same thing as tiling a shower surround? Just tile it as normal it will be fine.

 

[FishScreener]

Normal now includes a water proof, vapor permeable membrane.

 

[frodo]

Isn't this the same thing as tiling a shower surround? Just tile it as normal it will be fine.

nope, grout is porous , if you do not want to be replacing rotted sheetrock in 5 years
it needs to be sealed
you can remove the existing rock and install durarock / cement board

what you need to do, is leave that floor tile and the 10'' skirt alone
install the durarock lapping over it

 

[Mikey]

No need to remove the sheetrock if you use the Kerdi system. Just run the membrane up the wall to whatever height you want.

 

[jeffnc]

The advice for Kerdi is a good one, as that's the best waterproofing and will require the least change to your wall.

By your questions, I can tell you think the tile and grout itself is the key to waterproofing. It is not. The wall must be waterproofed first, then it doesn't matter what gets past the tile. Here is the best way to approach wet tile installations: assume that water will be getting behind the tile. That will drive your strategy.

However you can't waterproof on top of the existing tile skirt. That should be removed. Then you can see what waterproofing was done underneath. You have to tie in with that correctly, and that is the real problem. The seam between the old and the new is going to be the trick. You're going to have to figure out what's behind the tile to know how to add on to it.

To answer a couple of your questions, you should use thinset, not mastic or modern acrylic mastic-like adhesives. Thinset is water resistant, mastic is not. If using Kerdi, then a non-modified grout should be used, for example:
https://www.lowes.com/pd/TEC-Skill-Set-50-lb-White-Powder-Thinset-Mortar/50343088

As for the grout, the easiest thing for you to use is a grout such as this. It requires no sealing. It's expensive, but when you do all the math for alternatives, it's really not expensive.
http://www.mapei.com/public/US/products/2028301018-mapei-flexcolor-cq-en.pdf

 

[jeffnc]

nope, grout is porous , if you do not want to be replacing rotted sheetrock in 5 years

Yes but as FishScreener says, this is the new normal. The bathroom needs to be tiled as if it were a shower. Obviously, that means not tiling directly to drywall. However drywall is an acceptable substrate for some waterproofing products.

what you need to do, is leave that floor tile and the 10'' skirt alone
install the durarock lapping over it

If I understand you correctly, you are talking about leaving the 10" of tile existing on the wall??? I would not recommend this. This will leave a truly bizarre, curved out looking upside down ledge on your wall. The skirt tile should be removed. Hopefully they waterproofed with something underneath this skirt. If it's the PVC sheet liner most people use to waterproof shower pans, this is going to be a problem to be dealt with, because there's no way to connect Kerdi to this.