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Rubbertree 04-08-2012 11:33 PM

Unmodified Thinset
 
Alright...after searching through pages and pages of threads I'm not getting a straight answer, probably because everyone in the world is using Ditra except me. So,

Laid ceramic tile onto wonderboard (on my floor) using Kerabond Unmodified thinset.
Should I be expecting catastrophic failure or am I okay?
Thanks folks,
RT

JetSwet 04-09-2012 07:31 AM

Quote:

Originally Posted by Rubbertree
Alright...after searching through pages and pages of threads I'm not getting a straight answer, probably because everyone in the world is using Ditra except me. So,

Laid ceramic tile onto wonderboard (on my floor) using Kerabond Unmodified thinset.
Should I be expecting catastrophic failure or am I okay?
Thanks folks,
RT

Unmodified under cbu board and modified on top for tile install don't forget to mesh tape the joists. Is this how you did it or did u reversed it?

oh'mike 04-09-2012 07:40 AM

Go to the tile section and look for a 'sticky' called "mud,what is it?" By Bud Cline---very well written explanation of different thinsets---

You will be fine-(if you mixed and applied correctly)---Modified is prefered under tile---However,Unmodified over wonder board will bond well and should give you a nice long life.

JazMan 04-09-2012 01:01 PM

As Jet & Mike said, you're supposed to use modified thinset over the backer to install the tiles. However unmodified will work well as long as the tiles were not porcelain or glass. You didn't mention specifically what you installed. Please tell us.

Jet eluded to unmodified under the backer, did you spread thinset under it?

Jaz

Rubbertree 04-09-2012 05:20 PM

I was getting all excited, thinking I may have escaped disaster until JazMan came in...

I used unmodified thinset between the plywood and the wonderboard (and screws of course) and then got all eager and used the same thinset (kerabond) to lay the tile...which...upon closer inspection and some internet research, appear to be porcelain.
Here are my tiles:
http://www.ceratec.com/SKU.aspx?Lang...L13130000OAK01

Sigh....
I REALLY don't want to rip all this up, buy new tiles, and start over. Is there any chance this is going to hold up? I did skimcoat the tiles before laying them down.
Thanks for your replies guys and I'm hoping for some words of encouragement:)

JazMan 04-09-2012 08:47 PM

Well, not much you can do now. How big an area is this? Would it be a big deal to re do this in 2-3 years? Although you used the wrong thinset for those tiles, you might end up being OK anyway. I wouldn't guarantee it but you have a couple factors that should increase your chances. One, Kerabond is a very good quality unmodified mortar, and that you buttered the tiles too.

I looked up the ANSI spec and noticed the minimum shear strength when testing porcelain tiles using unmodified (A118.1) is 150 psi. The tested results with Kerabond comes in at 170-190 psi.

Of course had you mixed the same mortar with their appropriate additive the the A118.4 would have required 200 psi and the mortar would have rated 400-500 psi.

So, is 150-170 psi over a concrete backer enough to keep your tiles where they're supposed to be? Honestly I don't know, I've only set porcelain using a high quality modified when going over backers. We always use unmodified when setting over Ditra, but that's because Ditra eliminates the stress and is what is recommended.

How long have they been down?

Jaz

Rubbertree 04-09-2012 10:22 PM

They've been down going on 36hrs now. The area isn't that big...only 10x4 so to be honest its not like its going to take me days to replace them....just patience. I've been running short on that however...I have discovered that tiling is much like haircuts....there is a very good reason why people are paid to do it.
So, decision time...do they stay or do they go? I'll sleep on it...things always look rosier in the morning.
I appreciate your advice JazMan...I was hoping you'd be chiming in.

(Would it be rude to just put a "no fatties" sign on the door and leave it at that?)


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