Clarification on Kerdi

16 years ago

OK, I thought Kerdi was OK on top of cement board, but I am reading it is not OK. Are we saying Kerdi needs to go on sheetrock, period. That is fine, but I guess one needs to make a leap of faith and trust it. It is very enticing to think one can use sheetrock...how easy. And, should it be green or regular, or does not matter. Can someone clarify what happens to the raw cut end of the sheetrock that sits on the flange, does Kerdi have a procedure to deal with this? Couldn't it act like a sponge in case water gets past the caulk, or flows behind the tile and runs across the raw edge? I mined there site, but could not find anything.

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bill_vincent

16 years ago

I echo Sue's tile guy. Schluter says it's fine, but I don't trust it over sheetrock.

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Comments (7)

MongoCT
16 years ago
Kerdi can go on cement board or sheetrock. If sheetrock, use regular board, not MR. I always use cement board. Old habits die hard.

Kerdi on the walls is usually coupled with a shower floor consisting of Kerdi either over a preformed and presloped Kerdi foam tray (a shower base) or with Kerdi over a more typical drypack preslope.

With the above installations you have Kerdi on the walls joining Kerdi on the floor, which in turn joins with the Kerdi Drain. All that makes a fully waterproof Kerdi shower.

You can use Kerdi on the walls in conjunction with a preformed shower pan with flange or with a tub with a flange.

In those cases, I'd use Kerdi Fix to adhere the bottom edge of the Kerdi membrane to the base's flange. Kerdi Fix comes in tubes like caulk, or in smaller squeeze tubes. A little goes a long way.

Before you proceed, for a warm fuzzy feel free to call Schluter's Tech line and ask them. Good people over there.

Mongo
sue36
16 years ago
My shower was done with Kerdi on cement board. The tile guy refused to use drywall. The Schluter people said it was ok.
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Thank you again for your replies! The Kerdi over a Mud Base thread is great!! I have looked at the work of both contractors. The shower base and the grout lines done by the contractor who uses the Kerdi tray were excellent!! The only complaint I have is that he had very small tiles at the end of every other row. I think it could have been planned better. The tile work and grout lines done by the contractor who did not use the Schluter base were also good. The problem I have with his work is that the shower base was sloped toward the drain, but within inches of the drain, the slope increased dramatically. It looked like a hole, rather than the gradual slope of the Kerdi tray. In another install by this contractor, there was a noticeable bulge at the bottom of an outside corner. the other tile work looked great. This contractor is about $1000-$1500 less expensive than the other contractor. Can I mention my concerns to him and see what he says to address them? The following are shower floor dimensions excluding the curb: One shower will be roughly 36"x36". The other shower will be a Neo-angle about 34"x48". However, the 24" door will be on the angle with one side being about 19" and the other side being about 33". Can they or should they use the Kerdi tray as per Mongot's reply? Am I better off with a properly constructed mud base? I hope you can follow my explanation. Thanks again!!
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Weedy, You're the best. Thanks so much for doing that. I'm just about up to my elbows in Titebond (literally, I've used a little over 1.5 gallons today) so it would have been a while before I could have devoted time to savethe thread. If at all possible, sometime next month I'd like to go through the thread and tweak it a bit. Sort of add the details that we've covered since that were not included in the original text. I'll be in touch a few weeks down the road to ask you what I need to access the thread so I can edit it. Best, Mongo
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pharaoh
16 years ago
I did my shower with kerdi on drywall. i used the entire kerdi shower system. great product...
pirula
16 years ago
We took Bill/Mongo advice (and my husband's gut too) and used durock under the Kerdi. Okay, maybe it's like a belt and suspenders, but we wanted to be ultra safe.

Ivette
oruboris
16 years ago
What would be wrong with using it over MR drywall v. the regular stuff?

Current plan is for my builder to sheetrock, and I'll be doing my own tile work [I'm not that great at it, but I go slow and think things out-- more than some pros in my area can say].

I know he plans to use MR sheetrock in all the baths. I'm wondering if I should just put a layer of hardbacker [or similar] over that, then the kerdi system.

Or would it be better just to leave the drywall off completely?

Some of these are outside walls, if that matters...
MongoCT
16 years ago
You can use Kerdi over greenboard.

At times Schluter reps have waffled over the additives in greenboard and have written that if you're going to put Kerdi over gypsum board, use regular, not green.

But they do approve it over greenboard.

Mongo

Clarification on Kerdi

bill_vincent

Comments (7)

MongoCT

sue36

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