Porcelain Porcelain Tiles Unbonded

[Asc]

I have underfloor heating and a concrete floor. I cleaned the floor then PVAd it. I followed instructions on the bag of adhesive (cement based, highly polymer, modified, thin bed tile adhesive) The underfloor heating was turned off in advance. It was tiled using the trowel which was advised on the instructions from the adhesive bag (6mm square notched trowel). After around 10 days we heard some cracks and bangs but did not realise what this was. We turned the underfloor heating on, at the lowest setting after two weeks and we continued to hear cracks and bangs - we discovered that this was the tiles letting go. We have had to lift the whole floor, the tiles have come up with no effort at all. There is no adhesive stuck to the tiles (38m2 of 600 x 600 porcelain tiles) but it is stuck well to the floor. We have spent days taking the adhesive up with a hammer drill. On inspecting the granite tiles in the bathroom today they have also done the same and we are also going to have to take all these up and remove the adhesive from the floor.

Does anyone know what the problem could be?

The tiles appear to be quite powdery on the back - could it be this?

Or is it a problem with the adhesive?

Or something else we've done?

We have recently laid tiles ceramic tiles upstairs using different adhesive and have had no problems at all. (Although there is no UF heating there)

Would it help to clean then PVA the backs of the tiles before trying to lay them again?

Thanks for any help anyone can offer.

 

[Old Mod]

Ok so let's put records straight!

@Paul C. Has not made any comments that could be deemed as malicious toward anyone.
In all honesty, I'd imagine it was made because of a lack of concentration on his part and not the company that employs him.
And said WITHOUT prejudice, of this I am certain.
There was nothing underhand, this just was not the platform for his response.
Noting more, nothing less!
It was done publicly because the post had been up a while and we have no way of knowing who had already read it.

 

[J Sid]

Just because the adhesive says its suitable for ufh and porcelain we don't know if its not a bad batch or out of date.
To me it sounds like the wrong size trowel and not back buttered and possibly dry or skinning over of spread adhesive

 

[MW Smith Ceramics]

Just because the adhesive says its suitable for ufh and porcelain we don't know if its not a bad batch or out of date.
To me it sounds like the wrong size trowel and not back buttered and possibly dry or skinning over of spread adhesive

No adhesive on the back of the tile!.....wrong adhesive, fixing method and skinning over whilst fixing - ( not good )

 

[Asc]

Thanks everyone for replying and helping me figure out what to do next!

We started with a 6mm trowel but realised this wasn't enough so we got a 10mm trowel which we laid the same tiles in a small room with and the bathroom tiles but these have also come unstuck.

We were advised not to back butter the tiles but would it be better if they were back buttered?

I'm currently cleaning the backs of all the tiles as they are still very powdery in case this is the issue. (The powder was on the tiles before they were fitted) Would it help to seal the backs of the tiles with some kind of sealer?

Can anyone advise me which adhesive I should buy and what I should seal the floor with? I've always used pva just to stop any dust etc coming up off the floor

Thanks again for all the replies

 

[White Room]

The trouble with some tiles they can have a deep profile on back, I've seen 2mm before so that's why you back skim to level out the surface.

Back buttering is a deeper version, if the floor has a variation in depth, adhesive is what's available in your area but plenty of good adhesive out there Tilemaster, Ultra/Granfix, the latter are the same manufacturer....bal if your feeling flush.

No need to seal the back of the tile, if there that dusty a damp cloth will sort that out.

If you've already sealed the floor with pva a good wash with water will soften and scrape up, sbr would be my choice to seal the floor...thinned to a 3/1 with water.

 

[Andy Allen]

Who advised you not to back butter the tile ..?

 

[Spare Tool]

Thanks everyone for replying and helping me figure out what to do next!

We started with a 6mm trowel but realised this wasn't enough so we got a 10mm trowel which we laid the same tiles in a small room with and the bathroom tiles but these have also come unstuck.

We were advised not to back butter the tiles but would it be better if they were back buttered?

I'm currently cleaning the backs of all the tiles as they are still very powdery in case this is the issue. (The powder was on the tiles before they were fitted) Would it help to seal the backs of the tiles with some kind of sealer?

Can anyone advise me which adhesive I should buy and what I should seal the floor with? I've always used pva just to stop any dust etc coming up off the floor

Thanks again for all the replies

Was reading this thread at lunchtime,have always back skimmed every tile I fit, just do it automatically so thought id try a little experiment...pic is two same ceramic 250x400 wall tiles, one skimmed one not, same 8mm trowel, same pressure applied on fixing...whoever advised you not to butter tiles was a fool!!

 

[Asc]

Hi guys thanks for all comments and help and yes that shows very well that back buttering is a must thanks.

What's your views on Weber.set rapid spf I'm very restricted to what I can get as to where I live so is this stuff worth using

 

[hmtiling]

Weber spf is good gear imo. I'm not keen on their set plus with porcelain though.

 

[On one]

Weber spf is good gear imo. I'm not keen on their set plus with porcelain though.

I know what you mean about the Set Plus.......I use it,but.......it takes way too long to set and cleans off the tools way too easy.

 

[hmtiling]

I know what you mean about the Set Plus.......I use it,but.......it takes way too long to set and cleans off the tools way too easy.

I'll only use it with ceramics. Had to replace a couple of porcelain floor tiles and the bond strength just didn't seem to be there.

 

[Flintstone]

My guess is dusty back of tiles, incorrectly mixed adhesive and probably left on too long and skinned over, then Ufh on full blast from the start.

 

[Dan]

Don't mind me while I bump up some older but good threads. If you can contribute to the thread, go ahead. But if it's nothing for you then don't reply and it'll soon drop off the What's New page etc.
Worth linking to our new forum structure while I'm doing stuff:-

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