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.

 

[jobirdster]

Its the turning on and how the heat is ramped up slowly over the next week which is very important after the tiles and adhesive has set.
Turning the ufh on and taking it high straight away could give thermal shock leading to floor failure, looking like your floor looks now

Thank you to all who commented, we had someone independent to come out to assess on Friday and he has concluded that its the prep. Specifically no primer being used, which the tiler has admitted to only using the small bottle of primer that came with the UFH kit.

So now to get it corrected !

 

[J Sid]

From the pic's you posted I can't see it as a primer issue.
The adhesive has stuck to the floor and not stuck to the tile at all. Bad fixing method/no explanation.
Hope you get it sorted and maybe worth asking the next Tiler for commissioning process for ufh

 

[Anthony]

From those pictures posted it’s definitely the ufh getting to hot to quick! When tiles are insufficiently stuck they won’t crack and lift like that they’ll de bond and sit on the surface grout will crack giving that away. When stuck properly the adhesive will shrink and hold under tension (factor in curing time) then when heat is applied to quickly the properties of the adhesive can’t keep up causing lift and cracking. And debonding as tension is lost to quick. Certainly nothing to do with primer !

 

[eddcottee]

Where was this independent person from? I cant understand how primer is the issue, as the adhesive seems to have taken quite nicely to the floor. Albeit the adhesive has been poorly laid. If the issue was primer, the adhesive wouldn't have stuck to the substrate surely?