Who can identify the problem here? Crazy paving tiling - dodgy subfloor?

[James stibbs]

Following some cracked grout and then cracked tiles, I've lifted a couple of tiles in my bathroom this morning to find what you can see in the photos.

I'd like to re-lay replacement tiles but with the subsurface you can see, I'm not sure it's a good idea. The light blue you can see is like a hard foam. The dark blue is more like a hard plastic. Below this is some underfloor heating. Can you give me some advice on how to proceed? Can I just re-lay or is this a cowboy job and do I need to get this up and lay a new subfloor (something I really don't have the time or money to do).

If I can re-lay, I guess I'd need to take the adhesive up, which is going to bring the foam up. Do I replace it? If so, what is it? Thanks in advance for any help you can provide, tiling community.

 

[Flintstone]

Is this a solid floor or timber floor ? It's not looking promising for an easy repair. There's been some movement and thermal shock by the looks of it allong with poor fixing. What is the dark blue ?

 

[James stibbs]

Hey LocalTiler,

On closer inspection, it turned out that the dark blue is the heating element from the underfloor heating...

Underneath it all is a timber floor.

 

[hmtiling]

Looks like uncoated xps boards. If this is on timber with ufh then a rip up methinks.
Are there cracks in the grout on the rest of the floor?
By the look of the adhesive the tiles haven't been back skimmed so you may be able to salvage them

 

[Flintstone]

The light blue is uncoated board but the dark blue ? There looks to be a crack under the board too?

 

[James stibbs]

@Localtiler After a bit more archaeology, the dark blue is the plastic cover of the underfloor heating element. In this photo, you can see that some of the cracks follow the loops of the element. And yes, there is a crack under the board too. Good spot.Without pulling it up, I can't see if it's extensive or not. What's your diagnosis?

@hmtiling yes, most of the grouting is now cracked. Is it usual to set the ufh within the adhesive like this?

 

[Spare Tool]

Think the dark blue are the cables Andy..
Poor prep..all up and start again I'd say

 

[Chalker]

They have used uncoated insulation boards. Nothing sticks to them, so the adhesive is just floating. Then the ufh may have been switched on too early, or too hot.
Tiles haven’t been back buttered. So at least they might come up easily.
Unfortunately, will need ripping up and starting again.

 

[Waluigi]

It’s either a family of cement eating ants living nearby or some idiot tiled onto some bare XPS. Crazy.

 

[James stibbs]

Thanks to everyone who responded. I greatly appreciate it, even if it wasn't the news I wanted!

 

[widler]

@Localtiler After a bit more archaeology, the dark blue is the plastic cover of the underfloor heating element. In this photo, you can see that some of the cracks follow the loops of the element. And yes, there is a crack under the board too. Good spot.Without pulling it up, I can't see if it's extensive or not. What's your diagnosis?

@hmtiling yes, most of the grouting is now cracked. Is it usual to set the ufh within the adhesive like this?

View attachment 101555

Shower tray/screen leaking as well

 

[Unused Account 1]

Tiling onto foam ,really