# Tille over sealed concrete?



## ABN Homes (Jan 9, 2008)

My brother-in-law wants to put ripped up all the carpet in his house and used that quickrete stain and clear sealer on his slab. It was something different, and it looked alright, but the clearcoat is scratched all to heck, and now he wants to tile it. I have a couple of ideas, but wanted to bounce them off you guys to see if i am on the right track.

1. Use unmodified thinset and Ditra,then the normal process from there, but will the unmodified work on the sealed slab?

or

2. Am i way off mark here or could i use adhesive to secure the Ditra and then continue on. 
Any thoughts or ideas would be much appreciated.


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## [email protected] (Jan 22, 2008)

Im preety sure the unmodified thinset will work , thats what they recomend. Ditra is suppose to give u a crack membrane and also solve any moisture problems you may have . They say you should use ditra-set on top but I have used that or kera-bond, kera-lastic thinset both seem to work fine .


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## JJC (Nov 5, 2005)

How are the cement particles in the thinset going to bond with the cement particles in the slab if they can't get to each other because of the sealer? What you are proposing is for the 3 G's to do the work of the thinset, God, Grout and Gravity. If you want to have the installation last then abrade the slab to open the pours so that it will bond. You also are forgetting the industry standards of 1/4" maximum variation in the floor when measured with a 10'-0" straight edge. or 1/16" in 1 ft.. That leveling cement will have to bond to the slab so that it can support the Ditra bonded to the slab with unmodified thinset and the tile bonded to the Ditra with unmodified.


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## JazMan (Feb 16, 2007)

Jim,

Actually it's within 1/4" in 10 ft. AND 1/16" in 12" of required plane. :thumbup:

Jaz


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## JJC (Nov 5, 2005)

Hi Jaz,
Thanks, I was experiencing a brain cramp due to my senior status. At least thats my story and I'm sticking to it :laughing: .:thumbup:


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## Bill_Vincent (Apr 6, 2005)

Nahhh-- it's the weather up here right now-- brain freeze!!


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## JJC (Nov 5, 2005)

You're right, I'll blame it on the weather:whistling Stay warm Bill.


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## Floordude (Aug 30, 2007)

I wouldn't touch it without buzzing it all back down to clean substrate.


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## ABN Homes (Jan 9, 2008)

*tile over sealed concrete*

Thanks fellas for the input will put it too good use


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## CCSowner (Nov 9, 2007)

Floordude said:


> I wouldn't touch it without buzzing it all back down to clean substrate.


I'll second that.


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## ABN Homes (Jan 9, 2008)

I agree with grinding back down, but would i need to take it back down to bare concrete or just try to get to clear coat off. i am pretty sure trying to get back to clean substrate would be a bear.


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## JJC (Nov 5, 2005)

clean substrate! Remember why you need to go back to a clean substrate, refer to my original answer to you. If you want everything to stay together, you gotta go back to base one and then rebuild. check into renting a blast track or something similar.


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## Bill_Vincent (Apr 6, 2005)

If the concrete absorbs water, then you're down far enough. If not, keep grinding.


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## ABN Homes (Jan 9, 2008)

thanks


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## Bud Cline (Feb 12, 2006)

> Tiledogg: *Im preety sure the unmodified thinset will work* , thats what they recomend. Ditra is suppose to give u a crack membrane and also _solve any moisture problems you may have_ . They say you should use ditra-set on top but I have used that or kera-bond, kera-lastic thinset both seem to work fine .


Let's make some corrections for the benefit of the lurkers around here.

UNMODIFIED thinset would NOT be the proper thinset to use over sealed concrete OR under DITRA. This IS NOT what Schluter recommends. Schluter recommends the use of modified thinset under the DITRA. Attaching any tile product to sealed concrete is strongly advised against without first removing the sealer. The unmodified thinset would be the recommendation for use ON TOP of the DITRA when porcelain tile was used.

DITRA is in fact a crack membrane but really isn't intended to SOLVE any moisture problems. DITRA can be made to produce a waterproof membrane but solving existing moisture issues isn't one of Schluter's claims.

KeraBond/Karalastic is a fine product but would be overkill for most DITRA installations. There are more cost-effective thinsets available that will produce fine results.


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## css (Jun 26, 2007)

ardex rep recently gave me a factory warranty on a 1400sqft travertine job on sealed concrete we used ardex 8+9 for underlayment and ardex x-9 premium shearflex thinset it was awesome 8+9 you just mix it roll it and set tile in 2 hrs or can be water tested in 4 hrs maybe you should call them and see if it will wrok in your situation.


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## Bill_Vincent (Apr 6, 2005)

I'll tell ya-- if someone-- Ardex, or whoever-- could come up with a way to set over sealed concrete, that'd be great! I'd be on board in a heartbeat. But to say I'm skeptical would be a major understatement. Considering the fact that whatever you put over the concrete is only bonding to the sealer, and not the floor itself, it's taking a major chance. If that sealer lets go, Ardex is off the hook, because it was something beyond their control, and you can BET that they realised that when they gave you that "factory warranty".


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## Bill_Vincent (Apr 6, 2005)

Man, talk about ask and you shall receive!!

http://www.floorstransformed.com/ceramic_tile/messages/26249.html

For those of you who don't know Eric (E3) from FloorsTransformed or John Bridge's site, he's a rep for Noble, and I've known Eric long enough to know he won't steer you wrong, just to make a sale.


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## Teetorbilt (Feb 12, 2004)

I'd see how good the sealer is, a drop or two of muriatic acid will do. If it starts working, you're in and do a basic acid etch.


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