Pam's Basement Kerdi Shower

[pmcall]

Hi there, here's my first post. This board looks great -- so much solid information and helpful people.

I'm beginning to plan the renovation of a basement bathroom with a tiled shower. The shower walls are rotten and will be torn out and reframed to prepare for new tile.

The shower floor is 1 x 1 mosaic. I assume it's installed over a mud bed because the shower floor is higher than the concrete floor of the basement. The house was built in 1952.

Is it OK to put new tile on top of the existing mud bed (with or without removing the existing tile)? Or is it possible that the mud bed should be taken out and replaced? How do I determine this?

I would like to use the Kerdi system, having read so many good things about it on this board. I realize part of the existing bed will have to be removed around the drain, to get the new drain in.

I plan to live in this house the rest of my life, which I hope will be a long time, so I want it done right.

Thanks.

Pam

[muskymike]

Hi Pam, welcome. The kerdi system is a good choice for what you have. You will have to jack hammer around the old drain to get the kerdi one on. I would prolly leave the tiles and and do a new mud over the tiles. You will need a curb anyway unless your going curbless.

[pmcall]

Thank you, Mike. How thick would the new mud have to be -- an inch? So little headroom in the basement ...

Would there be any reason to consider taking out the old mud, moving the drain to the center of the shower (it's off to one end now), and using the Kerdi pan? It's a concrete slab underneath. I'd gain a few inches of headroom; but maybe more trouble than it's worth.

Pam

[cx]

Welcome, Pan.

I, for one, vote for removing everything (that mud shower floor is gonna pop right off the slab, I'm betting), centering the drain, and starting fresh with whatever shower construction method you like.

My opinion; worth price charged.

[muskymike]

Hi Pam, I missed that part in your post. CX is right get rid of the old mud and start fresh.

[Davy]

I've never liked the idea of tiling over tile in a shower. I'd remove it all to the studs, repair any damage and go from there.

[pmcall]

I think I'm on the right track now. Thanks for the advice.

Pam

[Davy]

Pam, time to get to work. First..... what's for lunch?

[pmcall]

Continuing to plan my new shower using Kerdi and have two more questions:

1) I want to have a couple of grab bars, which I understand I'd install after the tile is up, drilling through the tile to studs. This pokes some holes in the Kerdi. Is this a problem?

2) I'd like to use the tray that comes with the Kerdi shower kit. The shower will be 54 inches long, and I understand I can cut the tray in that dimension. But ... I'd like my shower to be more than 32 inches wide, maybe 38-40 inches. Any way to still use the tray?

Thanks.

Pam

[jgleason]

Hi Pam,

1. Make sure you add solid wood blocking in the areas you need the grab bars. Drilling through the tile/Kerdi won't cause any real problems. You will liberally squeeze silicine caulk into the holes and then scre your grabbars into place.

2. I'd ditch the pan and do a mud bed with Kerdi. You don't have to worry about trimming the Schluter pan or trying to extend it. also, if your drain is slightly off-center it won't be a problem with mud. Finally, mud is cheap and although it may seem daunting it isn't that difficult to do.

[pmcall]

I have some questions about my planned remodel of a small basement bathroom. It's about 4.5 x 12 feet overall and will have a 4 x 4.5 foot shower at one end with a quarter-circle monument bench in the corner (thanks to someone on this site's cool idea to use tree rings to make it).

I've taken a fancy to some transparent 1" glass mosaic tile, so I ordered a couple square feet from Hakatai to try out the installation. I've now learned that the tile will slide down the wall if you take the paper off too soon. And I think I can probably get the hang of it. It's a rustic, irregular design (Ashland), so it may forgive my learning curve.

I'm hoping to use the glass tile on the shower walls, bench and floor, as well as one long wall of the room. A total of about 170 sq ft.

The first question is whether this is completely crazy. That's a lot of tiny tile and grout joints. But I like the look, and I can take my time doing it.

If I'm not insane to consider this, I'm wondering about the materials to use. I definitely want to Kerdi the shower, yet the glass tile people say to use modified thinset. I did my test install using Versabond, which seems to be sticking OK so far, although it will require blue tape to hold the sheets up until it sets. From what I've read here, Versabond will be OK with the Kerdi as long as I wait several days to grout. Is this right, even for the shower floor?

I'm also considering a fiberglass-faced drywall because it's supposed to be less prone to mold and mildew. The concrete walls of the basement are behind the walls of this room. The walls will be insulated and built out with steel studs. Is this kind of drywall acceptable -- under Kerdi for the shower and by itself for the rest of the wall? If so, is it a good idea?

Thanks for any advice you may have.

Pam

[T_Hulse]

Hi Pam, I think It'll look great when you're done. Especially if you take your time like you said & do very small areas at a time. Versabond sticks great to the Kerdi, but not the glass. I would recommend something like Superflex, Megaflex, or Keralastic/Kerabond. If you called them & explained your application, Schluter might approve those types of super-modified or latex-added mortars for just this job if you let it dry for an extended time before grouting. Please note that the glass people probably didn't say to just use a modified thinset with water. They probably stipulated a liquid latex additive was necessary?

With mold, one of the biggest concerns is trapping moisture. Two vapor barriers in a wall section could do that. If the sheetrock core was actually from moisture resistant but breathable materials that would be great. But I wouldn't recommend anything with just another moisture blocking surface layer. Make sure the walls are at least an inch away from the concrete & that none of the insulation touches the concrete.

[pmcall]

Thank you, Tom, and you're quite right about the liquid latex additive. I'll go with one of the thinsets you suggest.

I talked with Schluter rep for my area (what nice people they have!) and he said using latex modified to set 1" glass tile over Kerdi is fine -- just let it set for a few days before grouting. He reiterated the need to use unmodified under the Kerdi.

When you say keep the walls at least 1" away from the concrete, do you mean space the studs away from the walls, so they're not touching the concrete? That makes sense to me and is how I was thinking to do it, even though I lose floor space (the old drywall was on furring strips, nailed flat on the wall).

The drywall I referred to is "Paperless DensArmor Plus Interior Wallboard," which has been recommended to me for the basement walls. As I understand it, it's just like normal sheetrock except the paper is replaced with fiberglass, which is supposed to be less prone to mold/mildew in dampish places like a basement. Are you or anyone else familiar with this product?

Thanks again.

Pam

[T_Hulse]

Hi Pam,
Yep, that's what I meant about the basement walls. I'm not familar with that product, so I'll ping CX & see if he knows about it.

[cx]

I merged all your threads together and gave you a new title, Pam. We can change the title to anything you want. Please keep all your questions about this project on this thread to avoid confusion and duplication of responses. When you make a post, your thread will pop up to the top of the queue, no matter how old it gets.

I'm not at all familiar with the Paperless DensArmor Plus Interior Wallboard. According to their web info, the facing is not a vapor barrier, so that feature shouldn't present a problem. But I think you'd be wasting any extra money it might cost in using it under the Kerdi. I also think you should axe Herr Schluter specifically about use over that product. They may have an opinion and theirs would be of substantially more value than mine on the issue.

My opinion; worth price charged.

Thanks, Tom.