QUESTIONI've just had the T shaped corridor tiled with 450x450 ceramics that match and continue the pattern from the kitchen. It appears that the tiles have been "spotted" rather than being laid on adhesive with complete coverage. The sound and evidence at door thresholds confirms that the bulk of the tiles have voids below. I've seen the videos for Fix-A-Floor which avoids the need to drill through tiles. Is it an effective solution for the problem. The tiles we've used are no longer available and the matching "perfect" tiles in the kitchen run wall to wall under the fitted units.
ANSWERANSWER - Spot bonding tiles leaving voids under tiles that produce hollow sounds is not an acceptable tile installation method in the industry.
Over the years when I have seen attempts to inject epoxy liquids through drilled holes in the grout joints, I have not seen it work successfully.
Although recently we intrusively inspected a tile floor that used Fix-A-Floor to fill the voids through holes they created in the grout joints, and I was surprised to see that it did work well. For the tiles we removed the voids were mostly filled with this product.