First problem in 10 years....

[Danj]

The job was a rush from start to finish to be fair so I wouldn't be surprised if the concrete hadn't cured properly although I did think it would take more than 2 weeks for them to pop. The builder is the only one who's played with the thermostat as the customers haven't moved in yet......nightmare situation

 

[Danj]

Thank you all for your input, much appreciated

 

[LM]

You'll know a lot more once you've lifted a tile. Take a few pictures of the lifted tiles and the screed for us. Don't over commit yourself with anything you say to the builder until you've had time to consider the findings.
It would be helpful if the builder is honest about the timing of turning on the Ufh and at what rate. Another possibility could be a faulty thermostat in the floor, I've seen floors fail due to this also.

 

[Old Mod]

the builder is honest

Don't want to diminish the severity of this thread,
But I don't think I've seen both those words in a sentence before! 😀

 

[LM]

Don't want to diminish the severity of this thread,
But I don't think I've seen both those words in a sentence before! 😀

lol, he's known him for 12 years so he should be able to get a sense if his telling porkies and then that might indicate a bit better as to what happened.

 

[Old Mod]

known him for 12 years

You sure Lee?

Sounds like working out why it failed will only take as long as it does to lift a tile.

 

[hmtiling]

i'd be surprised if it's anything other than a wet screed.

 

[J Sid]

could be a multitude of reasons from wet screed to adhesive manufacture problem to incorrect heat up. Until the OP has lifted a tile to see what's happen, no point guessing imho.
I've had one fail due to adhesive manufacture fault, one due to builder turning the to max from cold and the last job of the year, which looks like it is ok but thought it would fail due to the sparks wiring the thermostat by the front door (cold area due to workers in and out, so asking for more heat) to two of the three pipe circuits in the lounge. 2/3 of the floor was 29 degrees and 1/3 was 17 degrees, plumber and electrician both saying all is fine.

so I would say a full investigation is need and don't take the word of anyone.

 

[Danj]

Ok so I've removed the tiles to find dark patches and water literally running off the underside of the tile. I'm presuming this can only indicate too much moisture in the screed......

 

[Danj]

The majority of the adhesive has come up with the tile not stayed bonded to the floor