Bathroom tiles lifted

[jobirdster]

Hi;

I am a homeowner who recently had an extension built with a ensuite, we bought Pro warm electric underfloor heating kit and a 600 x 600 tile for the floor

We had them installed pre Christmas and this last week the middle section of the tiles have all lifted / peaked up and cracked. 4 tiles right in the middle of the bathroom are affected but all the other tiles now sound hollow too when we tap them.

The method for install was a thermal board, electric matt, screed and primer which came with the pro warm mat.
The tiler insists he has used a good quality adhesive Ultra Flexible
We did not turn the electric mat on for at least 6 weeks after install.
When I look at the back of the lifted tiles they are clean, no adhesive on them... adhesive seems to have stayed on the screed.

My questions.
Do we need expansion gaps on this size of floor with electric underfloor heating ? size is no larger that 3m x 3m tiles are 600mm x 600mm porcelain matt and are sold as suitable for underfloor

I have had another tiler out and he states that its either substandard adhesive, not being primed properly or no back buttering of the tiles.

The tiler who fitted them said he never back butters, the primer he used was supplied from the underfloor heating kit and the adhesive he used was Ultra Flexible.

Can anyone shed any light on what could have happened please ?

I need to find a solution/ idea of whats gone wrong so I can get the tiler to correct it.

 

[J Sid]

Expansion joint all round perimeter.
Not back buttering tile is the most likely cause imho
Pics are good if you can

 

[Dumbo]

As above i agree with julian

 

[jobirdster]

Hi Julian;

Thank you for your comments.

Here are some pics. Tiler who did the job told me no expansion gaps is needed on such a small area and he only back butters to fill up on an uneven floor gap, but not as a standard way to install.

Pics are attached to show you

 

[J Sid]

No explanation joint around perimeter looks like the cause
Should have back buttered but could still have popped without explanation joint.
Original tile should redo it

 

[eddcottee]

Julian, if there is no expansion gap around the perimeter then I get that is the likely cause, however when re-installing, along with the necessary expansion gap, would a decoupling membrane not be a good idea given what has happened to that floor already? Or do you not feel it necessary? Large format tiles with UFH says decoupling membrane to me, but I'm still learning the trade. Cheers. Edd

 

[Anthony]

did You turn the heating on gradually?
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As this looks to me from the way they have cracked and lifted like rapid heat ingress

 

[Dhtiling]

Pretty poor contact and trowel technique. Expansion joints at all edges are required. Back buttering helps with bonding, but not required. Heated floors were done properly for years before membranes came out, just looks to be a bad install. Shouldn't be able to see ridges from trowel.

 

[eddcottee]

Pretty poor contact and trowel technique. Expansion joints at all edges are required. Back buttering helps with bonding, but not required. Heated floors were done properly for years before membranes came out, just looks to be a bad install. Shouldn't be able to see ridges from trowel.

I did wonder about those swirls from the trowel. I was taught you have them all running in the same direction, then when you set the tile in, move it a few mm each way and back into place which collapses the ridges and gives you a good bed. Was also taught to back butter and have seen what a difference this makes whenever lifting to occasionally check a tile. Usually immediately after setting a tile down, if I have to lift it for some reason, it's really very hard work to pull the tile back up. I can't imagine those tiles would have taken any effort to lift back up.

 

[J Sid]

Julian, if there is no expansion gap around the perimeter then I get that is the likely cause, however when re-installing, along with the necessary expansion gap, would a decoupling membrane not be a good idea given what has happened to that floor already? Or do you not feel it necessary? Large format tiles with UFH says decoupling membrane to me, but I'm still learning the trade. Cheers. Edd

No membrane is needed with those tiles, thin porcelain and stone, yes.
Bad fixing technique, a membrane would not have helped in this situation Edd