Loose Tiles - can someone explain please?

The Tourist

Hi all,
I'm having a problem with the tiles in my bathroom coming loose. The set up is as follows:
- wood floorboards (with extra plywood over this I think)
- devimat underfloor heating (but I dont think this is responsible)
- tiles (12"x12")

The tiles are making a crunching noise. A couple at the edge beside the bath (which only have a very small part of the devimat under them) were very loose and I was able to take them up (whole) with a kitchen knife. The grout around them had crumbled and they just came free from the "adhesive" underneath. None of the adhesive came away with the tiles.

My question is a two parter:
Part I (a.k.a. who should pay for the repairs): I recently had a leak behind the taps in the bath fixed which caused some damage to the ceiling underneath the bathroom. Could this be the reason the tiles are coming loose or is it just bad installation?

Part II: What is the standard fix for this type of problem? I'd like to get in a professional, but I'd like to know more about it before I do.

Many Thanks.

Corkey123

Sound as though the tiles never bonded to the adhesive. This couold be evident by the lack of adhesive on the tile. You could take them up and re-apply more adhesive. It was most likely waterproof adhesive to begin with so the leak probably hasn't caused it.

beavisboy

for under floor heating flexible adhesive must be used. It sounds like ordinary adhesive was used hence the tiles poping up.

szd

you def need flexible adhesive if the tiles are on plywood otherwise they keep popping up.