Advice on marble floor tiles

[chrissbat]

We have just had marble tiles laid in our new extension, purchased from a well-known retailer. We used a tiler recommended by the shop, who appears to have done a good job, although there were problems with some of the tiles being different sizes and thicknesses. The tiles were laid on a concrete screed with electric under-floor heating underneath it. Very soon after the tiles were laid I noticed that several of them have cracked, presumably as the adhesive dried. The shop manager came to look at them and as a result the shop has agreed to replace the cracked tiles free of charge, with adhesive and grout. However, they are not prepared to pay for labour in taking up the cracked tiles and replacing them. They say there was nothing wrong with the tiles (in which case, why are they replacing them?) - the fault must lie with the under-floor heating (which hasn't been on) or the screed not having dried properly. However, we also have a wooden step which has no screed or under-floor heating and one of the tiles has cracked on this. I do not really want to have the tiles taken up with an angle grinder, both because of the mess and because the screed and under-floor heating may be damaged. On the other hand, we paid a lot of money for these tiles and it is annoying that so many of them are cracked and chipped before we have even started using the room. They have cracked along veins in the marble. I suspect that the marble is of inferior quality, but I would need an independent expert to verify this. I do not know how to resolve this issue - is there a trade body I can ask for legal advice? The tiles were sealed before they were grouted. Is there any sort of resin that can be used to coat them and stop the cracks getting worse, or should I get them taken up? I would appreciate advice. Thanks.

[wes56]

prep'ing is 90% of the job in tile work.thats down to the tiler.
plus you say different size and thickness tiles?thats down to the shop
but why did the tler fix odd tiles if the idea was to lay similar matching tiles? why did you let them?
the u/f heating might cause more problems,why not call the ufh mfr for a heads up?
citizens advice might be your next stop.
sounds like eventually you might have to lift the floor anddo the whole thing again

[chrissbat]

Hi Wes, thanks for your reply. I didn't make it clear in my question that the tiler didn't actually use the tiles that were the wrong thickness/size, apart from some on a step, not the main floor. I took them back to the shop. I mentioned it to show that the tiles were not great quality. He didn't use a membrane or matting between the screed and the tiles, but I have been told this should not be necessary on top of screed. The screed had been left for about 10 weeks to dry before tiling, although it was in the winter, so perhaps it wasn't fully dried? Thanks for your advice.