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Tile Pro - Consulting
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331 Posts
I could be wrong, but I doubt you spoke with Mr. Schluter himself.

In any case, it is generally not a good idea to have 2 vapor barriers on a single surface. It may not create a problem in every situation, but we know that vapor can be trapped between them. I don't know if there's much evidence of failed systems built that way, since I doubt many showers are done like you describe. It may not matter that the "sandwich" is thinset mortar, but we do know it is not necessary to have 2 barriers and possibly harmful to build walls that way. We may know in 10-20 years?

Why not just follow Mr. Schluter's recommendations? Even Swiss cheese would be watertight with Kerdi on it! :clap:

Jaz
 

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21 Posts
With the Wedi, only Kerdi-band on the seams. CBU, Kerdi the entire surface. It might be overkill, but I usually use CBU & Kerdi.
 

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Carpe Diem
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No I didn't talk to Mr Schluter personally. That's why I used quotes. I talked with my local Schluter rep. I sent him the info (Kerdi over DensShield), he researched, called me back and said Schluter gives a thumbs up for that combo. He said something about DensShield not truly being 100% waterproof. I don't recall the entire conversation as it was about a year ago. I think he said something about a percolation test that showed water could pass through DensShield under certain circimstances.....blah, blah, blah.
I've already said why I use DensShield...it has nothing to do with any kind of waterproofing on GP's part.
Now if Schluter says it's OK to use Kerdi over DensShield, who am I to think otherwise? Who should I listen to in this case, experienced tile setters or Schluter?
 

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Tile Pro - Consulting
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331 Posts
Yea, I used to use DenShield too, I used it for about a year or so. Why did I? Basically because it was so much easier and lighter, well...cheaper too.

All I can repeat is what I have learned thru the years of doing, reading and listening. I would have no problem using a regular CBU such as Durock and Permabase etc. if I still couldn't believe that regular drywall is the recommended substrate for Kerdi. The truth is that Kerdi makes whatever substrate you wanna use completly watertight. I would worry about using Dens if I went thru all the trouble of applying a liquid membrane on seams and fastners. That may be what the Schluter rep was thinking in reference to dens not being 100% impervious? I can understand that. It took me a few years to switch to unmodified thinset when going over Ditra.

Well, chances are that you won't have any problems. I've removed many shower walls that did not have a barrier on the studs with no ill effects.

Jaz
 

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Carpe Diem
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20,533 Posts
Jaz,

I'm far from trying to be a trail-blazer here. I'm not trying to "buck the system" or anything. I also had the same concern with DensShield allegedly being 100% waterproof and using Kerdi over it. After talking with Schluter, they convinced me that DensShield is not truly 100% waterproof and they actually recommend Kerdi over it. I fully believe when Schluter says they recommend a procedure, it is the way to go.
As a K&B remodeler, I normally have the luxury of spec'ing more than just the wet location walls. I always use DensArmor in bathrooms. If I can get away with using it in a shower/tub location and then layering with Kerdi, I will. But it doesn't make too much sense for me, say in the back alcove wall of a 60" tub surround to use a 4'x8' sheet of DensArmor, cut it up and have 25% scrap. When it's most convenient for me, I'll use DensShield.
Don't forget, I even talked with GP about Kerdi over their product and they said "no problem" too. After hearing from both GP and Schluter, I don't have any regrets using DensShield when it benefits me.
Thanks for all the input. :thumbsup:
 

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Tile Pro - Consulting
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331 Posts
What I was trying to say about Dens and Kerdi is that Schluter recommends wallboard, and although Kerdi will work over almost anything, why do it? The size factor has some merit, but it still costs more, regardless.

As for the Schluter rep, how does he know how good a job you are doing by going over spots with a liquid membrane? I would say your method makes the DenShield not waterproof, but very vapor proof. More so than the average installation.

Jaz
 

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Carpe Diem
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although Kerdi will work over almost anything, why do it?
When I remodel a bathroom, I only use DensArmor for wallboard. If I can get by with continuing the Armor into the wet location to cover with Kerdi, I will. However a 4'x8' sheet of Armor is definitely more expensive than a 32"x60" sheet of Shield, especially if I have to waste 20%+ of the Armor.

As for the Schluter rep, how does he know how good a job you are doing by going over spots with a liquid membrane?
I don't know what you mean. I treat the Shield the same as CBU, fiber tape seams and thinset. I don't use a liquid membrane. I Kerdi directly over.
 

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bathroom guru
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1,348 Posts
I am a huge Schluter supporter, however, I used drywall as a substrate once, and once only. Now it is Concrete board, although I am going to try some other products.

As for Denshield, it is definately not water proof, but as far as using it behind Kerdi - I think you would get a better bond than drywall
 

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bathroom guru
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I can't believe the moderators of this site kicked the bathmagician off!!

From the look of that one post, we should be paying him just to have the opportunity for him teach us the ways!!
 

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I am remodeling a master bath for a customer and he has asked for the kerdi / schluter shower material in a E mail to night .
Ive been building steam showers out of durock or wonder board with a vinyl liner and mud floor for a long time . Ive never had a leak or moisture problem before . Whats the purpose of the new material ?
I'm kind of a cave man when it comes to new plastic stuff.
I have always felt good using cement in the shower . John
 

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Carpe Diem
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Whats the purpose of the new material ?
I'm kind of a cave man when it comes to new plastic stuff.
I have always felt good using cement in the shower
Kerdi has been around since the 80's, that's far from being new.

It's made from polyethylene covered with a fleece layer for thinset to "grab" onto. It's 100% waterproof. CBU is not. :no:

Kerdi is not the only membrane out there, but I'd suspect it's the most widely used. Like I said, membranes are not new. The theory of actually waterproofing wet locations, especially a steam shower, is one of the best ways to stop being a caveman! :thumbup:
 
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