Grouting has been done too early.
Tiles falling off wall tile adhesive.
Thinset is best adhesive.
The most common cause for falling tiles is water infiltrations.
Tile falls off wall organic glue skins over.
Be sure to spray the wall surface with water to activate the glue.
Otherwise the repair may not hold and the tile may also sit a little higher than the ones next to it.
Incorrect tile grout used.
This means it is thick enough to easily bridge differences between the two mating surfaces.
Over time the mortar holding a wall tile may fail to do its job letting a tile become loose and fall.
The wall surface could have been irregular with humps and dips in it.
Use a glue that is gap filling.
Then prep the wall and use the adhesive made specifically for the tile you have.
If water gets behind the tiles and in the grout mildew can grow and it will cause the adhesive to deteriorate.
Apply grout around the tile on the gaps between the tiles.
The adhesive needs to be applied evenly and on every tile.
You should leave the tile adhesive to set for at least 24 hours before grouting the tiles.
Since the tile is flat and in the same plane the wall surface must also be a perfect match.
Use a piece of cloth to remove any adhesive that is displaced above the tiles.
Make sure that the tile adhesive that you use is water resistant.
Lloyd s bathroom tiles failed when either the wall wasn t prepared properly or the mastic was exposed to too much.
Press the new tile down over the adhesives you have just applied.
Make sure that the tile is level with the existing tiles so that you don t end up with ridges.
If no adhesive is applied then the tiles will fall off.
Give the adhesives 24 hours to set.
This is not just a threat for your tiles but also for your health.
Clean off the old stuff from the back of the tile and from the wall.
Many people strip the loose tiles sand them and reposition with new adhesive.
Or take them all down putting wax paper between each tile so they don t get damaged.
Though more common in an older home rogue tiles can be found in new homes as well.
Often the adhesive will skin over if exposed to the air for too long before the tile is placed this means the adhesive looses its suction so the tile does not stick properly.
Make sure that they don t come into contact with any water during this period.
How do you fix it.
Was the adhesive left on the wall for too long before you placed the tiles.