Opinions on floor failure

[Al@Lifetiles]

I have an idea what’s gone wrong here but would be interested to hear other opinions.
Old property which had a floating wooden floor removed and replaced with 60mm foam backer boards (wedi or similar) over the concrete slab. Electric ufh latexed over then tiled. The concrete was “blackjacked” then boards bonded to the floor apparently (I wasn’t able to ascertain this without ripping up more of the floor) Tiles came up clean with the adhesive stuck to the back of the tile. Nice solid bed so no signs of dot n dabbing. No evidence of a primer. Also no perimeter expansion. Floor has enveloped in the centre of the room, heaving and cracking the latex. Signs of thermal shock which will have popped the tiles but still confused with the massive cracks in latex.
Sorry for the long post and appreciate feedback.
Cheers

 

[Dumbo]

Funnily enough there is already a thread running on this floor .
There is a good chance the blackjack has let go as this doesn't withstand hydrostatic pressure which doesn't normally matter when you have 127 kg a metre of screed on top but your floor build up is a lot lighter than that .

 

[Al@Lifetiles]

Small world! ill have a look for the existing thread.... thanks for your reply

 

[J Sid]

Do you know the ufh wire output? Looking at pic by patio doors looks like you can see wires spaced well apart, so possibly low output and thermal shock seems unlikely IMHO.
Tiles coming of clean, to me I'd say, unprimed / contaminated slc.
The cracks clearly look like debonded boards is the problem

 

[Al@Lifetiles]

Thanks. I can find out the output but yes the wires look well spaced.
I thought the work, on the whole, looked to have been well done but the results are a complete failure! Id be interested to know what advice would be given for reinstating the floor given the height restriction and the obvious failure of this construction?

 

[sau98rpe]

Al was an absolute legend taking a look
Over it at the weekend! It all needs to come up but I can’t afford take 2 to go wrong and need to Tick every box to make sure it remains solid and warm!

 

[Al@Lifetiles]

there is a huge amount of knowledge and experience on this forum so hopefully we can figure out what went wrong and what can be done moving forward. Take plenty pictures when you are digging up the floor!
The feedback so far suggests the boards are floating on the concrete so it might not be too difficult to remove....