Floor Fail - TilersForums.com

[White Room]

I was asked to look at a floor which has failed twice, first time it had been down 8 months the tiles had become loose, builder came in and removed and relayed with the same tiler who fixed them first time.
It's now been down since march and becoming loose again, had a look and managed to pull a tile up.
18mm ply with ufh, slc laid (allegedly) and customer has no idea what wattage the ufh is, laid with Ultra rapid set.

What do you think may the problem why it failed.

 

[Chalker]

Rubbish adhesive?
No back buttering?
Movement in the ply?
Mixing adhesive too thick?
Not enough coverage?
Movement in the steps?

 

[Spare Tool]

Rubbish adhesive?
No back buttering?
Movement in the ply?
Mixing adhesive too thick?
Not enough coverage?
Movement in the steps?

All of the above..
Looks like he started with a trowel then gave up...not much sign of slc

 

[White Room]

All of the above..
Looks like he started with a trowel then gave up...not much sign of slc

There wasn't really, just a smidge and so thin it was breaking up

 

[Spare Tool]

There wasn't really, just a smidge and so thin it was breaking up

...pointless then

 

[Chalker]

Looks like really cheap slc. Water based/ non flexible, to be crumbling like that.

 

[One Day]

What do you think may the problem why it failed?

Err, tiled by morons?

 

[Kyle Knowles]

Yeeee Haaaaa the tile cowboys strike again

 

[Time's Ran Out]

The way they cut the skirting round the socket says a lot!

 

[SJPurdy]

in addition to all the above factors (not solid bedded being clear in the photo) the joints appear to be a bit narrow (are they minimum 3mm?).
Where the adhesive has made contact with the base of the tile it seems to have stuck to the red pen but not the tile so dusty tiles could be another factor.