Floor tiling problems

[stevie25]

Hi
Went to see a job the other day, 60m2 timber floor which has been tiled about 1 yr ago . In areas there is cracks in grout etc which I put down to movement , it's an extension and ah told me she's had the builders back To repair areas that were bad tiles popped cracking etc. I lifted couple tiles there's piped underfloor heating under the ply but also the builder hasn't used a subfloor he's plyd rite onto joists 18mm ply.were I think this is a part of the problem . I haven't done a floor with the heating Pipes just the mats etc . Do u need to use a matting or other coverings when installing tiles onto ply when ufh piPes are used ??
Any feedback would be much appreciated
Thanks
Stevie25

 

[Time's Ran Out]

The preparation of the sub floor is all wrong. 18mm plywood direct to the joists and tiled straight on just asking for tiles to crack. If its deflection free it should still be over boarded with a hardie tile backer board as a minimum before any tiles are fixed. What insulation has been used and how are the pipes supported.

 

[stevie25]

Dont know how pipes are supported , won't know till we lift floor don't think any insulation has been used , what do u suggest??
Thanks