Tiling issue after 8 years

[Tigger90]

Hi, I have a solid concrete floor with electric under floor heating (that I never use) and then tiles. This was all installed by the builder/tilier when my house extension was built 8 years ago.
This week I have noticed that approximately 2sqm of the tiles have a crunching sound underneath them, it seems that they could be movement but the grout is still fine. This section of tiling is next to the bi-fold doors.
Do you think that adhesive could have failed?
Thanks

 

[PrenticeBoyofDerry]

Do you think that adhesive could have failed?

Either that or the subfloor or base floor

 

[vinn]

As above.
Or moisture has penetrated past the door or from under the door threshold perhaps?

 

[Tigger90]

Thanks both. I have taken a look at my paperwork and the foundations are a slab foundation, which is at least 600mm thick. There is no sight of any moisture inside and the outside looks fine.
This part of the floor is a sun trap so I did wonder if it had just dried out too much?

 

[vinn]

Pics of the inside floor will help.
You will now have to most likely lift all the suspect tiles and post more pics when the bed is exposed.

 

[Tigger90]

Here is the inside.
I am going to give the building company a call in the morning and see what they say.
I won't be lifting the tiles as I would not want to damage the underfloor heating or the tiles !!

 

[vinn]

There's no signs of lipping or loose grout - & the floor looks flat.

The tiles appears to be too tight to the bottom door frame - & grout has been used in the edge join instead of some kind of color matching sealant.
IOW: theres perhaps no room for expansion - and you have UFH and its a "sun trap"?

 

[Tigger90]

The room is only a sun trap when it's sunny, the rest of the time it's just normal temperature. I had the UFH installed as it was the latest fad, but I don't use it use the central heating radiator over the winter..
I might contact the tile suppliers as well, see if they have had any feedback on tiles/bifolds.

 

[foxhole]

The edge of the floor may have insulation which has deteriorated with the heat. If the subfloor was not packed tight to this it could allow it to crumble .

 

[Tigger90]

I spoke to the tile supplier and he said it was most likely the concrete slab contracting and expanding at a different rate to the tiles. They supply a product that can be used between the layers that can stop the issue I have but it's not much use to me now! He said to keep monitoring it but if they tiles are not moving and if the grout is fine it will be something I will have to live with.
I know the slab is a heck of a lump of concrete as it cost me just shy of £4K, so that would hold some heat!!

 

[chappers]

to be fair decoupling membranes were barely heard of 8 years ago