How to tell if contractor used modified thinset [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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06-27-2008, 11:40 PM
I am in a dispute with a builder over why porcelin tiles are popping .the builder installed the 1/4 " hardi backer underlayment. He used liquid nails in large S patern and 8d ringshank nailsin the marked places on the hardi backer . When the job was done there was no warranty on job because of that . Now lo and behold 2 years later tiles are popping . He refuses to believe that it is from hardii backer deflection and says its the thinset used was not modified. is ther any way to test the thinset to prove it is infact modified. Or should i just call a hardi backer rep to see the floor and make the desision. to recap hardi backer installed with liquid nails and 8d siding rinshank nails.4 corners meet and there is apparent deflection .grout and tiles popping . also although there was no warranty with the install i live in a small town and would like to remedy this but do not want to take responsability for something that falls on his shoulders also does it matter since he installed the hardibacker wrong anyway and ther is deflection. he wants me to tear up the floor and redo it but i would be destroying the evidence that could prove i am not at fault.

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Tool Guy - Kg
06-28-2008, 02:49 AM
Welcome to the forum. :)

So the contractor voided Hardi's warranty by: Not using thinset under the backerbaord, not using "up to spec" nails, and not staggering the joints. But rather than talk about those errors, he's shifting the blame on the mortar because he says it wasn't modified? Uhhh........okay.......Even if the mortar was to blame, what arguement is he using with the mortar to excuse himself?

The contractor did chose and purchase all the materials, right?

06-28-2008, 03:41 AM
Thanks for the reply. no the builder just improperley installed the hardibacker.I supplied the thinset and set the tiles and grouted . The warranty is voided from the hardibacker being improperley installed and the grout cracking is from deflection as well . I cannot remember if I used a modified thinset or not. I am a wood flooring /laminate installer and was pressured into this by a store I sub from. Is the tile popping from the deflection ( there is obvios movement in the hardibacker), or the thinset ?How can I be sure. Quite frankly I don't think its my problem anyway but the builder is including me on this replacement 2 years after the fact . I just want to be sure one way or another that I am not at fault, take responsibility for my part if I am and wash my hands of the whole mess. Or should i just tell him to ..... well any way its bugging me to the extent that i am writing this at 2:36 a.m.Any advice will help.

06-28-2008, 06:17 AM
i believe the tcna did a series of tests between unmodified/modified mortars to determine their bond strength to porcelain, since schluter requires the use of ONLY unmodified over their Ditra underlayment

you might print a copy off of schluter's website (see below) to show the builder that although unmodified does not stick as well to porcelain as a modified mortar, it does exceed all the industry standards.......thus the use of an unmodified mortar by itself shouldn't cause a failure IF and i specify IF the proper trowelling and setting techniques were used, see in particular pages 26, 27 of the Ditra handbook

then ask the builder why he thinks he is such an expert tile failure investigator if he doesn't know the first think about cbu installation procedures, you should also investigate the deflection of the subfloor, i.e. joist spacing and joist material too see if the substrate is unacceptable for tile in the first place, otherwise it might fail again.

06-28-2008, 07:43 AM
you should also investigate the deflection of the subfloor, i.e. joist spacing and joist material too see if the substrate is unacceptable for tile in the first placeI agree with Rick, this could be the problem and not the Hardibacker.

I'll be surprised if you can get a Hardi rep out to the job, they will probably ask how it was installed and say "that's the problem"

*why didn't you put down the Hardi when doing the tile install ?
did the builder just decide to do it to save time & money?

is there any way to test the thinset to prove it is infact modified.I think most tile guys can scratch thinset and smell the additive in it. I know I can tell by smell and by how a piece crumbles. not the most technical, but it works when I need it. :)

06-28-2008, 09:51 AM
A most excellent example why competent installers agree only to their own floor/wall prep, materials and industry standards for tile installation. :D

Tough call Ė the builder didnít follow installation guidelines for the backerboard. Can you provide proof that you did for the tile? The type of thinset used is questionable, how about your method of installation? If the tile wasnít imbedded properly (sufficient thinset and backbuttering), even a good modified wonít keep the tile from popping. What kind of coverage is on the back of the tile that popped?

Show that you did in fact install and comply to industry standards and the problem will be borne on the builder :D

06-28-2008, 10:56 AM
When the tile pop off, where is the thinset and what is the state of the cbu underneath? If the tile came up with no thinset stuck, you've got an install error on that, but if the cbu is flexing, you have bigger problems.