Tile on drywall above jacuzzi tub

[KPROOF]

Hi Everyone,
I am new to this forum and I'm hoping someone can help me. We are installing a Jacuzzi corner tub in our new bathroom. It will be installed in the corner of two exterior walls (and we live in Upstate NY, not sure if climate matters) and we want to tile between the bottom of the windows on those walls and the platform of the corner tub (about 18"). However, we already installed sheetrock below the windows to the floor. Can we just tile over the sheetrock or should we use something like Kerdi membrane then tile ?

Thanks,
Pak

 

[Jadnashua]

Personally, I'd prefer the drywall wasn't there. Without a shower, technically, it's a dry area, and it shouldn't matter. There will likely be some splashing, but not much.

Is there a horizontal surface outside of the tub lip on the platform? If so, what's on that? Can you post a picture of what your area is going to be?

People tend to think of tiled areas as waterproof...they're wrong. Tile is a decorative wear surface. A tub only isn't as critical as a shower, but I'd still like some way to ensure moisture didn't get places I didn't want it.

Kerdi could be used over the drywall, but terminating it properly is important, too. You might just use the KerdiBand at the tub/wall junction, but I'd like to see how the tub/wall and platform all connected before being more specific. That would take care of any moisture that might sit on the rim. Since there's no spray, I don't think you'd need to worry about it higher up as long as you protected the drywall from wicking from below.

 

[Sponsor]

 

[KPROOF]

Personally, I'd prefer the drywall wasn't there. Without a shower, technically, it's a dry area, and it shouldn't matter. There will likely be some splashing, but not much.

Is there a horizontal surface outside of the tub lip on the platform? If so, what's on that? Can you post a picture of what your area is going to be?

People tend to think of tiled areas as waterproof...they're wrong. Tile is a decorative wear surface. A tub only isn't as critical as a shower, but I'd still like some way to ensure moisture didn't get places I didn't want it.

Kerdi could be used over the drywall, but terminating it properly is important, too. You might just use the KerdiBand at the tub/wall junction, but I'd like to see how the tub/wall and platform all connected before being more specific. That would take care of any moisture that might sit on the rim. Since there's no spray, I don't think you'd need to worry about it higher up as long as you protected the drywall from wicking from below.

Yes, I wish the drywall wasn't there either, but unfortunately, it's already up! We did think about cutting it out & putting up cement board, but we're trying to avoid that. There will be about a 9" horizontal surface outside the lip around the back side of the tub. We will be installing cement board there, but haven't gotten to that point yet. I've attached a picture that I hope will help !

 

[Jadnashua]

None of the paint-on waterproofing materials I've found can be installed over drywall, so, if you want that area protected, you're stuck with one of the two sheet membranes that are rated for use over that wall-board. Just for peace of mind, I'd probably use Kerdi on the wall and the top of the deck.

 

[KPROOF]

Ok, that's what we were thinking about doing. And it's okay to put Kerdi over cement board ?? So the platform will be pressure treated plywood, cement board, Kerdi membrane, then tile.

 

[Jadnashua]

The ICC test report that is the certification document for a Kerdi shower build lists cementitious backer units (cement board), gypsum board (drywall), and a few other materials as acceptable backers for their product. https://icc-es.org/report-listing/esr-2467/ That certification expires and gets renewed after a new review by the independent testing agency, and has been in effect for Kerdi since it was introduced decades ago...it works if you install it properly. That test report is what allows the system to pass a building inspection, assuming it is used as indicated.

 

[Cacher_Chick]

The cost of removing that drywall and replacing it would be nothing now compared to 3 years from now if it starts to absorb water at the tub deck.

 

[Jadnashua]

The cost of removing that drywall and replacing it would be nothing now compared to 3 years from now if it starts to absorb water at the tub deck.

If Kerdi is properly installed, that drywall won't ever see any moisture, at least originating from the finished side of the wall. It's one of two sheet membranes that has been approved for use over drywall in a shower, and should work just fine for some splashes from a tub only.

 

[KPROOF]

If Kerdi is properly installed, that drywall won't ever see any moisture, at least originating from the finished side of the wall. It's one of two sheet membranes that has been approved for use over drywall in a shower, and should work just fine for some splashes from a tub only.

 

[KPROOF]

We ended up removing the sheetrock between the bottom of the windows & the platform framing and will be installing cement board. However, should we put plastic up behind the cement board and if so, do we remove the insulation with a vapor barrier and replace it with unfaced insulation ?

 

[Jadnashua]

It depends. If you're still going with Kerdi, then, no, no moisture barrier behind. If you're going to just use the cbu, then yes. It makes it a bit harder to ensure water doesn't seep into the wall/deck joint.

CBU is not waterproof, but is not damaged by getting wetted. Some of them wick moisture as much as 6" up vertically. You still need to protect what is behind. Without a shower, moisture shouldn't be regular, and you can get by with being less stringent.

FWIW, Kerdi over drywall works fine and is their preferred backer, partly because it comes in larger sheets and is easier to carry and cut. It will work over a bunch of other materials.