# Marble tile over Ditra or Blanke or Durabase w/ modified thinset?



## ND2 (Jan 1, 2013)

Looking for advice on which decoupling material works better and what thinset can be used (modified or unmodified). 

I am doing a large kitchen with marble tile (12x18).

Subfloor includes osb and 5/8" ply. Joists are 16oc.

I understand Ditra recommends modified thinset on bottom and un-modified thinset on top. Most tile manufacturers will not warranty unless a modified thinset is used. Anyone have any advice on this? 

Blanke Permat seems to accept modified thinset on the top surface, but it is rather expensive.

Durabase Cl is very much like Ditra, except it includes a mesh on the top surface. Anyone know what thinset can be used with Durabase?

Thank you.


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## angus242 (Oct 20, 2007)

Subfloor does not sound like it's remotely close to being strong enough to accept a natural stone tile installation.

Forget crack isolation. Read up on how to build a solid enough subfloor system _before _you worry about such things as a membrane.


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## Inner10 (Mar 12, 2009)

angus242 said:


> Subfloor does not sound like it's remotely close to being strong enough to accept a natural stone tile installation.
> 
> Forget crack isolation. Read up on how to build a solid enough subfloor system _before _you worry about such things as a membrane.


Shot down with so little information?

Maybe it's 3/4" OSB and the joists are 14" and span only a few feet...:whistling


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## JazMan (Feb 16, 2007)

ND,

Yes Angus kinda jumped the gun with his answer based on very little info. If the subfloor sheets are 3/4" OSB plus 1/2 ply. you've got plenty. But we don't know about the joists yet.

Please give us the size of the joists, their species and grade, and the unsupported span to the inch. We already know the joists are 16" oc so good.:thumbsup:

Now to your tile selection. Are you sure you want marble? What kind of marble, be specific.

As for the membrane, I vote for Ditra.

Jaz


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## Floormasta78 (Apr 6, 2011)

Ditra under marble... 
Go for it ! 
But you have to use modified, I would ..


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## ee3 (Feb 10, 2006)

however-for the record Ditra is not Crack Isolation,it does not meet the ANSI 118.12 Stadard for crack isolation. :no:


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## JazMan (Feb 16, 2007)

Eric (ee3) is right. Ditra is not and does not claim to be a crack isolation membrane. They call it an "uncoupling" membrane. 

If you need crack isolation go look here. www.noblecompany.com 

* Floormasta78, what do you mean by; "you have to use modified"? 

Jaz


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## Floormasta78 (Apr 6, 2011)

I don't follow the Ditra suggested unmodified thinset suggestion. 

I don't believe in that. It's stupid . 
Modified .. Only on my jobs


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## JazMan (Feb 16, 2007)

> I don't believe in that. It's stupid .


What is? Who is? 

Unmodified for tiles over Ditra and Kerdi works perfectly. But I understand that some people have a hard time especially when installing porcelain tiles. They have been wrongly thinking that unmodified mortar will not bond well to porcelain. It sticks very well thank you:thumbsup: and because of the way Ditra and Kerdi work, a good bond is achieved without complications. 

What kind of mortar do you suppose they used to install porcelain tiles before the '70's when additives were introduced? Many millions of bathroom floors, pools and commercial jobs of mosaics were installed without modified mortar. 

However, it's not a problem to void any possible warranty by Schluter and go ahead and use modified mortar. I did for several years before I realized I didn't have to.

Jaz


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## ohiohomedoctor (Dec 26, 2010)

I have a hard time believing that the same products they sell in Europe only work in Europe. In my opinion the whole unmod schluter usa debacle is just a way to push their ditra set which costs them less to make and they sell for high end prices.

Somewhere there is a dirty french mam laughing his rear off about this whole deal.


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## ohiohomedoctor (Dec 26, 2010)

We tore out this tile today that was 12 years old or so and was laid on 1/4 hardie 1rst gen nailed conservatively, over 3/4 plywood, and not a single cementous grout joint cracked. The tiles came up three at a time with a roof stripping shovel and not one cracked.


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## JazMan (Feb 16, 2007)

Matt,

Your reasoning is way off base.

Ditra was introduced in 1987 and Schluter was not interested in getting in the thinset business. They were happy simply recommending the use of a premium unmodified thinset and leave it there. But since it wasn't clear which thinset was considered premium, they finally licensed Bostik to develop a high quality mortar to meet Schluter's specs.

Bostik's division Hydroment came out with Ditraset in late 2005 and was widely available in 2006. I find the cost of Ditraset is only $1-3 more than other similar mortars such as Laticrete 317. And Ditraset is better than 317. There's no big profit in the product. 



Matt said:


> Somewhere there is a dirty french mam laughing his rear off about this whole deal.


Maybe there's a joke in there some place, but you know Mr. Werner Schluter is German, from Germany. The guy is brilliant, Ditra - Kerdi _ Kerdi Drain - and hundreds of other inventions. 

Jaz


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## Floormasta78 (Apr 6, 2011)

Jaz, using unmodified is a stupid idea . I don't use it. I only use fast set or regular 253 gold.


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## ee3 (Feb 10, 2006)

they didnt start the Unmodified kick until about 1996.
I think you would see the shear strengh is much better to the tile with a mod vs. un-mod.I'm not saying it wont work, it will ,but its not as good of a bond to the tile.
I think they call out for a ANSI 118.1 mortar.I have never seen in a ANSI standard ,or on the bag of thin-set'"GOOD".It meets the standard or it does'nt..There is better, but, it allows for any by the standard. If I'm not mistaken, in the UK they call out for Modified. 
The original Ditra was totaly different then the current with a different explination of how it works. Just like in the UK there is Kerdi DS for Steam units with a much lower Perm Rating but here Reg. Kerdi is ok. 
Nobleseal came out in 82 ,several year before Mr. Schluter invended it.


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