Another case of hollow tiles

[RedSpottedSev]

Hi,

 

Another hollow tiles decoupling help please.

We have had 96m2 of 60x90cm porcelain tiles laid in a 2/3 pattern.

There is wet UFH, covered with screed, then primed, then decoupling applied, then the tiles were placed.

I was there for the start of the works and they were back buttering and laying with notched trowel.

It was all perfectly level and beautiful, however after 3 months started to notice the grout lines showing signs of movement, and now at least 4 tiles have play in the corners.

 

After reading about the issue, tapping every tile, it seems all around the edges of almost all the tiles are hollow.

I drilled 3mm holes depth of 2cm in the corner joints and 20cm distances along the grout lines. Got some fix-a-floor to fix the ones that are moving, and also to put around any tiles showing signs of movement but can't feel the movement.

 

I am fairly disheartened as today one side of a tile gullupped up x2 of the tubes and Im not even sure if it is all filled. Each tube is £13. I just can't afford that rate of fix a floor per tile (As I was planning on doing the lot)

 

My question is, can I get an alternative to get down through 3-4mm holes to preemptively fill all gaps to try and save a full lift up (which would involve moving out the house and family has already had enough of the renovations over running). Can self levelling compound or othe adhesives be mixed thin and put down there? Any ideas welcome... 

 

Thanks