The chalk dust will stop the tiles from adhering to the wall.
New tiles falling off wall.
Only mix enough thinset as you can use in one hour or less.
Only apply as much thinset on the wall as you can cover with tile in five minutes.
Be sure to spray the wall surface with water to activate the glue.
Make sure that the tile adhesive that you use is water resistant.
Then prep the wall and use the adhesive made specifically for the tile you have.
If the board is soaked from the ground.
Grouting has been done too early.
If no adhesive is applied then the tiles will fall off.
Slide a chisel behind the loose tile.
Adhesive has not been applied properly.
I ve seen half a wall in a shower 50mm away from the real wall.
This will allow for easier removal of the loose tile and.
Do not add water to the thinset if it starts to get hard in the bucket before you spread it.
Install the new tile of course you must select the right tile for the job to begin with.
Gently tap the chisel with a hammer to fully remove the tile from the wall.
Also the grout may have been too wet or made wet over and over during installation.
Use gorilla glue to replace each one.
What it boils down to is that if the substrate fails substrate is the surface the tiles are mounted on then the tiles will fail.
Remove the tile if your bathroom tile hasn t already fallen away entirely but merely broken you will need to.
There are a number of factors that keep tiles on the wall any of which can cause the tiles to fall off if there is a problem.
Or from the shower hard to say if no spacers were used tiles can force each other off as they grow lets say a tenth of a mm when hot and wet.
How to re stick tile on the wall 1.
Or take them all down putting wax paper between each tile so they don t get damaged.
Use cold water to mix the thinset to retard the setting time.
Cut into grout around the loose tile using a utility knife.
Chip away old mortar.
The adhesive needs to be applied evenly and on every tile.