"Lifting " floor tiles

[Frederick]

I have just experienced my first "out of the blue " happening with the lifting of floor tiles. An area that was where the sun hits the floor through a window lifted and on removal of 30 tiles I discovered they had been laid direct onto the concrete floor without any floor tile cement under them .....it appears the floor tiles were put down dry  then grouted after to hold them in place .....I can only assume that air trapped under the tiles was heated up after being left  cold over winter  expanded and up they came .? I have put them back OK with waterproof  floor tile cement and they seem to be well anchored down now ....... is this normal practice ...slap them, down dry and just grout them in ?

[Poppy]

It might be that the tiles were laid not dry but on an ordinary cement  mix not special tile cement.this is often normal practice. I think this works OK with old traditional terra cotta tiles but not new materials.

[Frederick]

Thanks Poppy......I  think you are right as the area is  in a bedroom that is part of an extension and not the same tile as the older part of the house .... even though the colour is similar to the older thicker ones......oh well .....I can expect to have to put a few more back down then !