On occasion, a marble tile may crack. It can happen thanks to anything, from being struck by a dropped object to constant pressure from a leg of heavy furniture. But you don't have to live with the imperfection or replace the entire floor. Instead, you can remove the damaged marble floor tile and replace it with a new one.
The difficulty of this repair process can vary a bit, depending on if the flooring was installed with a traditional bed of mortar, or by the more modern method of using thin-set adhesive. Either way, the process is pretty much the same as replacing a ceramic tile or any form of natural stone tile. It involves breaking the damaged tile, prying or chiseling out the tile and mortar, then inserting a new tile and grouting the joints.
Before You Begin
If you are lucky, you have kept a few replacement tiles from the original installation. This is by far the best option since the tile will be a close match with the current flooring. If you have no leftover tiles, you may be able to purchase a replacement tile from the original source. This might be tough since marble is a natural material and each lot has a unique look. Popular colors and patterns tend to change over time. If you didn't hold onto replacement tiles, you may have to do a bit of research to find a near match to your original tile.
Equipment / Tools
- Carbide-tipped grout saw (or Dremel tool with grout blade)
- Eye protection
- Work gloves
- Nail set
- Masonry chisel
- Putty knife
- Medium-grit sandpaper
- Foam brush
- 1/4-inch notched trowel
- Needle-nose pliers
- Rubber mallet
- Wet cloth
- Dry cloths
- Old screwdriver
- Grout float
- Grout sponge
- Scrap piece of 2x4
- Leveling compound (if needed)
- Replacement marble tile
- Marble sealant
- Thin-set mortar or tile-setting mortar
- Plastic tile spacers
- Tile grout (color-matched to original grout)
- Grout sealer
Remove the Tile Grout
Using a carbide-tipped grout saw, or an electric Dremel tool with a grout-grinding blade, carefully remove the grout from the joints around the broken tile. As you work, be careful not to chip the edges of adjacent tiles. At the same time, grind out as much grout out as possible to make it easier to remove the tile itself.
Break the Tile
After the grout is gone, break the tile into pieces that can be easily removed. Position a nail set at the center of the marble tile, and strike it sharply with a hammer until one or more cracks begin to radiate out from the center. This may require several blows.
Be on guard for shards of marble flying off from the tile; these shards can be sharp enough to cut skin. It is vital to wear eye protection and gloves during this step.
Remove the Tile
Insert the tip of a masonry chisel into one of the cracks, and tap the end of the chisel lightly with a hammer so it buries its way under the tile. As you do this, make sure that you maintain a shallow angle with the chisel, so that the tip does not gouge the underlayment beneath.
Once the chisel is sufficiently under the tile, you should be able to pry the piece away from the cement board or plywood below.
Scrape, Smooth, and Flatten the Underlayment
Lift, chisel, and scrape away as much tile and adhesive or mortar as you can, using a chisel and putty knife. The effort this requires will depend on the material used to apply the tile. With thin-set adhesive installations, it will be relatively easy to scrape smooth the cement board or plywood underlayment. But older installations may use a layer of hard, cement-like mortar troweled over a metal lathe as the bed for the tile, and with these, you'll need a considerable amount of effort to smooth out the underlayment.
Once the underlayment is exposed, use medium-grade sandpaper to sand down the surface area, making it as smooth and flat as possible. Any rises or depressions can cause areas of weakness that will make it easier for replacement tiles to crack. If necessary, you may need to repair dents or damage in the subfloor using a leveling compound.
Seal the Replacement Tile
Marble is a very porous material, and a replacement tile can get stained during installation if not properly prepared. Using a foam brush, apply a light coat of a marble surface-sealing agent to its surface. That will create an invisible barrier over the tile so that adhesive and mortar will not damage or stain it.
Apply Mortar and Place the Tile
Mix a small amount of thin-set adhesive or tile mortar, according to the manufacturer's directions. Then apply it directly to the back of the replacement tile, using a 1/4-inch notched trowel.
Press the tile down firmly into its place by hand to bed it in the mortar. Insert plastic tile spacers at the corners to ensure the grout lines are consistent with the original grout joints.
Level Out the Floor
Lay a scrap piece of straight 2x4 over the flooring, and lightly tap it with a rubber mallet to force the new tile down into flush alignment with the surrounding flooring. Move the 2x4 around over the high spots, and make sure to tap lightly to avoid any chance of cracking the tiles.
Clean the Tile Surface
Use a wet cloth to remove any thin-set adhesive or mortar from the surface of the tile. An old screwdriver can be used to remove any adhesive that seeped up along the grout lines. The joints should be empty to provide space for the grout.
Allow the thin-set adhesive or tile mortar to set up for 24 hours. After a few hours, use a pair of needle-nose pliers to remove the plastic tile spacers from the corner joints around the tile.
Grout the Joints
Because grout may stain the surrounding marble tiles, you may want to seal the tiles that surround the repair area before grouting the replacement tile. If you do seal the surrounding tiles, make sure to allow the sealant to dry fully before proceeding to grout.
Mix the grout and allow it to set up for the period recommended. When the grout is prepared, apply it to the joints around the replacement tile, using a grout float to force it down into the joints. Holding the tool at a slight angle will help the edge force the grout down tightly into the joints.
Use a large damp grout sponge to wipe away excess grout from the surface of the tile.
As soon as the grout dries, wipe away the powdery residue with a dry, soft cloth.
Seal the Grout and Floor
Once the grout has dried according to manufacturer recommendations, the grout joints must be sealed. Use whatever sealer is recommended by the grout manufacturer, and apply it with a foam brush.
As a finishing touch, you can now seal the entire floor. It is usually recommended that the surface be sealed every 6 to 12 months. Sealing the entire floor may also help the new replacement tile blend in with the surrounding area since sealers slightly alter the color of the marble.