In a case where cracking is minimal or has occurred in only a small number of tiles and or the floor is in a location where aesthetics don t matter to you the easiest most inexpensive solution is diy patching.
Tile floor crackles.
I also think the double wax ring on the toilet has failed as evidenced by the blistering paint in the ceiling board and recessed light below.
The tile makes scrunching noises in over half of the floor and the grout is crumbling in many of the joints.
In this test floor tiles are run through a machine that exerts loads on an unsupported 1 inch square area.
Generally hairline cracks in the concrete will not present an issue to the tile floor above.
For a larger more visible area of cracked tile contact a tile contractor for expert help.
As long as the tile does not break under 250 pounds of pressure the tile is considered to be compliant with these standards.
Most tiles comply with astm c648 breaking strength standards.
As a general rule tiles larger than 12x12 inches should have mortar applied to the back of the tile as well as the floor to help ensure adequate coverage.
In many cases cracked tile floors are signs of foundation issues it s possible that soil movement or water has caused your foundation to shift move or even be pushed in an upward direction.
Voids in the mortar under the tile allow the tile to flex and crack.
Most tiles meet the 250 pound minimum.
Sometimes hairline cracks in tile floors are one of the first tell tale indications that soil or moisture is affecting a foundation.