Tiles Keep Cracking

[RP13]

Hi, after some advise if possible! I laid a natural limestone floor in my house over piped underfloor heating. It's a pump screed that had been down for roughly a year and tested super dry on a moisture meter. It's a new system boiler system . So after a year I fitted the heating system turned it on and roughly over a week and a half took it through its paces before shutting it off and leaving to cool for 3 days. I then used keracol primer 2 coats. Before putting the limestone tiles down fully surrated to the floor using the h40 Eco ideal adhesive. I then used bal super flex grout. I left the heating of for 2 weeks after then turned it on at its lowest on both boiler and underfloor heating. I've had about 6 tiles completely crack! Has anybody had anything similar or may have an idea because this one has truly confused me! Never had an issue like this before! Any help would be appreciated!

 

[J Sid]

Was an uncoupling membrane used?

If you take up these tiles is there any cracks in the screed?

What was the screed exactly?

Any pics?

 

[J Sid]

Reading about the adhesive, it states for 'Stable natural Stone' 🙁
Isn't most stone 'Unstable' by its very nature......

 

[Time's Ran Out]

Was the limestone dry prior to fixing?
For me I would always use uncoupling over wet underfloor heating and such a soft stone.
You'll have to take 1up to see if it's tile or screed that's contracted. Was it a fast set adhesive?

 

[RP13]

Anthracite screed. No membrane used was told by the rep it wasn't needed. It's not in one area there just randomly broke mainly at the edges where there is a gap. I've lifted two there stuck well had to smash it to get it out there is a fracture in the screed under one but I don't understand why this didn't happen when I ran the heating up before.

 

[RP13]

It's a natural stone supplier where the tiles came from that advised that adhesive. Said they had had 'no problems' with it but I guess that may be sales talk I don't know was nice to use issues only occurred when heating came back on. Wasn't rapid set.

 

[Dave]

Stone tiles debonded and cracking ? .. Incorrect prep of anhydrite sceed maybe ?

 

[RP13]

They haven't debonded. As for the prep I sanded all of the area and primed with correct primer two coats 90 degrees
To each other. Exactly what they stated was carried out. There doesn't seem to be any loose it's just the ones that are cracked

 

[J Sid]

Ufh and Stone, uncoupling membrane or I walk.
I'm not up on these anhydride screeds, but should they crack like that? I've only seen one other one and that had cracks all over, so walked away.

 

[J Sid]

So you are saying there was no cracks in the screed before tiling only appeared after you tiled?

 

[RP13]

when I originally ran the heating up I had 2 hairline cracks appear. One where the pipes are brought into the room and one where the sink pipes come out the floor but no others. The tile where the pipes come in had cracked but I can't understand how if it is the screed underneath why didn't it crack originally but when its tiled cracks within 24 hours of the heating back on at low burning

 

[RP13]

Thanks for the reply by the way sending me mental trying to figure it out

 

[Rizzle from the Portizzle]

you might find when the floor was not tiled it defused the heat very quickly through the screed now tiled the heat needed to get through is higher .and the layer between the screed adhesive and tile is not vented but sealed with the tile so the screed is getting a lot hotter causing cracking

 

[Time's Ran Out]

Looks like your going to have a bit of work to do to rectify your work!
From the photo and your info the screed had cracked in places so the signs were there and the correct substrate preparation should have been approved - using an uncoupling membrane. However the cracks may continue to develop so it may be ongoing.

 

[Just Rizzle]

no decoupling membrane that's the problem your screeds cracking and following through the tiles

 

[Tile Shop]

How big is the area?
How long did you have the tiles before they were fixed and where were they stored?
Have you left a perimeter joint or used any expansion strips?

 

[RP13]

Hello mate biggest area is 7mx3.6 I left a perimeter gap but no expansion joint. I had the tiles 2-3 months prior to fitting and they were stored in the living room area ( the only room not tiled)

 

[hmtiling]

Ufh and Stone, uncoupling membrane or I walk.
I'm not up on these anhydride screeds, but should they crack like that? I've only seen one other one and that had cracks all over, so walked away.

There's only one company that do them here and they crack more often than they don't.