# Recommended gypcrete underlayment?



## Aaron Tritt (Feb 4, 2011)

I am sure this has been discussed here, but I couldn't get the search engine to work for me...

So when you are tiling over gypcrete over wood what do you use an underlayment? 

Hopefully nobody just goes with thinset and tile...

TCNA says whatever you use needs to exceed ANSI 118.12 (1/8" crack prevention minumum), and many products meet this minimum standard.

In the past I have used Redgard and Mapelastic primarily. Is there anything you have found either more profitable and equally as good, or safer for the installation?


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## angus242 (Oct 20, 2007)

I'm thinking Noble EXT Primer, Noble EXT and NobleSeal.

If I get a chance, I'll call tomorrow and verify but from my understanding, EXT Primer is specifically for use over porous concrete. Gypcrete is porous.


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## Tech Dawg (Dec 13, 2010)

angus242 said:


> I'm thinking Noble EXT Primer, Noble EXT and NobleSeal.
> 
> If I get a chance, I'll call tomorrow and verify but from my understanding, EXT Primer is specifically for use over porous concrete. Gypcrete is porous.


Eric is out of the office until Thursday :laughing:


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## angus242 (Oct 20, 2007)

He was out 2 weeks ago until Friday 

I want his hours!


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## Tech Dawg (Dec 13, 2010)

From what I got is they have been doing more seminars and also some training with Laticrete on drain stuff so maybe he's outa town....
...or at the beach :drink:


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## greg24k (May 19, 2007)

Use Ditra and be done with it, is the best way to go :thumbsup:


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## angus242 (Oct 20, 2007)

greg24k said:


> is the *best* way to go :thumbsup:


I'm not sure non-modified over gypcrete is _best_.

I've used Ardex Feather Finish over gypcrete before laying Ditra :thumbsup:


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## greg24k (May 19, 2007)

angus242 said:


> I'm not sure non-modified over gypcrete is _best_.
> 
> I've used Ardex Feather Finish over gypcrete before laying Ditra :thumbsup:


This is a nice product Angus, used it a few times... very durable, easy to work with but the down side is, you can walk on it only in about 3 hours, and I know for a fact that you have to wait 24hr to install any floor covering over it. *(Let me correct that... We used ARDEX V-120 that what the specs called for I never tried the Ardex Feather Finish, I've seen in the box store.) * They also have another product K55 which is a rapid self drying product, with that one you can install flooring in 3 or 4 hrs. The only down side is you can only bring this up in 1/8 lifts and if the floor is out of whack by a substantial amount, there might be a problem using that. I never used this stuff with Ditra, but if this will work, then I guess he can take a shot at it.

While on the subject, there is another product SL-150 by Bostik which is high strength and high compression, and also self-leveling cement-based underpayment, we will be using that on a remodeling job of a small shopping center... I am working up a price now and I will check if this product can be used with Ditra. 

On the general note, we did so many floors in different enviroments not only residential but also commercial projects, and we never had any issues with un-modified being used under Ditra, no call backs, no issues whats so ever.


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## angus242 (Oct 20, 2007)

My concern is not with non-modified under Ditra, it's with non- modified over gypcrete.


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## greg24k (May 19, 2007)

angus242 said:


> My concern is not with non-modified under Ditra, it's with non- modified over gypcrete.


I understand your concern, but my understanding about Ditra engineering technology, is that they are not worried much about expansion and contraction in underpayment, not to mention that gypcrete it self is a flexible product and has flexibility.
The main concern when placing down Ditra is to make good even spread without any voids between un-modified product and sub-floor and Ditra itself. Un-modified product will create some sort of a bond with underpayment but that is not the main concern...What ties everything together and makes this system work is after the dimpled surface is filled with thinset and tile is set, the whole package becomes whole and that is why it can take a substantial amount of abuse or even a structural lateral movement, without causing tile to pop, crack or for the grout to become lose, etc. IMO.


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## rmmaurer (May 7, 2010)

*NobleSeal*

Gypsum underlayment producers recommend ia crack isolation membrane over gypsum underlayments before installing tile. They also recommend priming the underlayment. 

Noble recommends that the floor be primed using the primer recommended by the gypsum manufacturer [e.g. Maxxon Overspray for Gypcrete]. After ther floor is primed, bond NobleSeal to the gypsum underlayment with NobleBond 21. 

All NobleSeal sheets are "High Performance" crack isolation membranes [ANSI A118.12]. Choose any NobleSeal sheet. They are all rated High Performance and can also provide waterproofing. Use NobleSeal SIS when sound reduction is needed.:thumbsup:


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## jarvis design (May 6, 2008)

Has anyone used laticrete 125 sound and crack adhesive? I haven't, but remember it from the laticrete course I went to last year. It exceeds ANSI A118.12.


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## Floormasta78 (Apr 6, 2011)

I've used it , for the creamy consistency its amazingly hard but very flexible at the same time.. Its a perfect product..


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