Porcelain Porcelain Tiles Unbonded - Tile Advice

[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.

 

[J Sid]

PVA..... Really? That was the instructions on the adhesive bag was it ?

 

[White Room]

Don't use pva it has no place in tiling as there better products out there....what was the make of adhesive you used.

 

[J Sid]

What adhesive was this?

 

[Asc]

It was Kwik flex adhesive
Kwik Flex Grey Floor Tile Adhesive Toolshed Tile Adhesive Adhesives & Grouts 20 Kg from Walls and Floors. Kwik Flex Grey Tile Adhesive | Walls and Floors - Sold Per Unit

The pva was on the floor and the adhesive stuck well to this, on initial checks it appeared to stick to the tiles but 98% on the tiles had no adhesive stuck to them at all after the two weeks.

What should I be using instead of Pac?

Thanks

 

[Asc]

*pva

 

[Chalker]

To be fair to the op, even using the dreaded pva. The problem had been detachment from the tiles!
We need to know what make of adhesive, fast or standard set, how was it mixed, what are the tiles, were they back buttered, was the screed tested for moisture, what type of screed is it?
And could you post some pictures.
Thanks

 

[Bill]

PVA would not cause any harm to the adhesive - it may stop the adhesive debonding. Are you sure it was PVA and not another primer supplied by the tile shop?

Adhesive not sticking to the tiles is caused by the wrong adhesive being used for the type of tile.

 

[Andy Allen]

Should of used an acrylic primer.

Was the ufh commissioned before tiling
How long after tiling did you turn the ufh on .....and how did you turn the ufh on for the first time....did you just crank it up ?

 

[Chalker]

Adhesive is not the best , but should be up to the job.

 

[Andy Allen]

Could be the heating turned on to soon and to high.

 

[Asc]

The tiles were not back buttered - should they have been?

It's a solid concrete floor which has been in for four years - the underfloor heating went in at this time and was turned on Dec 2015, it was only turned off to tile.

We turned it on at the lowest setting after two weeks.

The tiles are porcelain.

They are very powdery on the back - could it be this?

What adhesive would you recommend?

 

[Asc]

Polished Ivory Floor Tiles Tiles Lounge Porcelain Tiles 600x600x9.5mm from Walls and Floors. Polished Ivory Tiles | Walls and Floors - Sold Per Sqm

Premium Star Galaxy Black Tiles Tiles Imperial Granite (Star Galaxy) Natural Granite Tiles 305x305x10mm from Walls and Floors. Premium Star Galaxy Black Tiles | Walls and Floors - Sold Per Sqm

These are the tiles we've used

 

[Asc]

Could be the heating turned on to soon and to high.

How long should we have left it? It was on the lowest setting on the manifold but were going to speak to plumber and sparky to see if we can set it lower

 

[Bill]

I think you need to get your tiler back and start negotiations with the shop from where you bought the products.

It is too difficult to assess online.