Replacing a cracked ceramic floor tile can be easy or difficult depending on the reason for the crack. If the tile is loose and those around it are not, it could be a bad installation and replacing a single cracked tile is easy. If others around it are loose, then there is a larger problem than a single cracked tile.
If there is a crack in the concrete or cement bed under the tile, you will need to follow section 2, to prevent a repeat of the problem. Also, the crack in the underlayment will eventually cause adjacent tiles to crack as well.
Tap the tile on both sides of the crack to determine if it is loose. If either or both sides are loose, use the flat edge of a screwdriver to pry up the tile at the crack.
Chisel the tile at the crack as close as possible to the centre of the tile. Gently tap through the tile at the crack until you are all the way through to the sub-floor.
Continue chipping away at the tile, expanding your starter hole until there is only a small amount of tile left around the edge.
Place the flat edge of the screwdriver against the outer edge of the tile aimed toward your hole in the centre. Tap it gently, forcing the edge of the tile loose. Continue in this fashion all the way around the tile to remove the remaining pieces.
Scrape the floor beneath the tile with the putty knife to remove setting material. Scrape around the edge of the tiles still on the floor to remove excess grout.
Measure and cut a piece of fibreglass tape to cover the crack in the sub-floor to the edges of the tile still installed. If the crack extends under adjacent tiles, you will need to decide whether to remove more tiles. If adjacent tiles are loose, follow the directions in section 1 to remove them. If they are still well-bonded, it is best to leave them in place.
Spread a little glue over the crack, to the width of the tape, with a putty knife. Place the tape over the crack and flatten it into the glue with the knife until it will allow the replacement tile to lie flat.
Wait for the glue to dry. This will create an flexible membrane, preventing movement in the crack below to affect the new tile.
Test the fit of the tile and make sure it sits flush. If the tile doesn't sit flat, use the putty knife to scrape the floor and remove any setting material, being careful of the tape, if used. If you can't get the replacement tile to quite fit in the space, use tile snips to remove the spacers located on the outer edge of the tile. Grip the spacer with one side of the snips, letting the other side grip the back of the tile. Grip and twist to pop off the spacers. It should now slip into the hole easily.
Spread a thin coat of glue on both the floor and tile with the putty knife to ensure a good bond. Place the tile in the hole and press down until it is flush. Wash any excess glue from the tile and out of the joint.
Spread grout into the joint with the putty knife, then smooth the grout using a damp sponge. Wash excess grout from the tile as you go. Allow the grout to dry and polish with a dry towel.
If you can remove the old tile in large pieces, you can look at the back of it to determine the manufacturer. If in doubt, take the piece or pieces to a tile distributor. They will be able to help with the identification, even if the tile is not theirs.
Don't assume all 4-inch ceramic tiles are the same size. The sizes can vary by as much as 1/4 inch.