If you notice that one or two (or in bad cases, several) tiles have developed a crack across a corner of the tile, then it is almost certainly due to faulty application of the adhesive.
If your cracking is in straight lines across several adjoining tiles refer to another Tile Doctor segment on cracks.
The tiler has not achieved full coverage of adhesive under the tile and there will be a 'void' under the tile. When pressure is applied to that tile, it will crack. This can be a chair leg, table leg or even someone walking over that tile with stiletto heels. The pressure on that section of tile, if it is not supported will cause it to crack or break.
It is easy to find if this will happen to any more tiles in the installation, or if it is an isolated one or two. Tap the tiles with a hammer handle or screwdriver handle. Where there is a hollow sound, there is a void below the tile and that tile is a contender for a future crack.
• Simply, there is not enough adhesive on the floor, under the cracked tile to support it fully. This is why tilers will lift a tile at regular intervals during a project to check that they are achieving full coverage.
• It may be that your tiler is a 'dobber.' He will butter adhesive onto the back of a tile and then place it in position. The correct method is to apply adhesive to the floor and then bed the tile into the adhesive.
The tiles were not laid correctly and rectification is needed.
The damaged tile or tiles should be removed and replaced by the tiler or builder who is responsible. While they are on the job, a check should be done for any other tiles that are also drummy.
