Damage and Repairs

• When laying ceramic tile over ceramic tile, the existing tile must be solid and level. Checking the tiles for broken or damaged areas or missing grout is required. If any tiles need to be repaired or grout needs to be added, this must be completed first. Putty that hardens may be used to repair the tile. Use a level and ensure the floor is level before proceeding.
  
  

Preparation

• Preparing the existing tiles before laying the new ceramic tile helps ensure the bond properly forms. Vacuuming the floor then moping with a mixture of equal parts white vinegar and water helps remove dirt that prevents a secure bond. After the tile is cleaned, allow it to dry and use coarse sandpaper to rough the surface of the existing tile.
  
  

Bonding Agent

• For the tiles to bond to each other, a bonding agent, such as cement mortar, is required. Applying the bonding agent with a 1/4-inch trowel and leaving grooves in the mortar helps ensure the tiles bond properly. Mixing enough mortar for one hour helps ensure your mortar is fresh and does not begin to set before you use it.
  
  

Considerations

• Since ceramic tiles have a range of thickness from 1/4 to 3/4 inch, consider the height of your floor with tile before installing ceramic tile over it. Adding an additional 1/4-inch ceramic tile may cause problems for toilets, cabinets, bathtubs and existing fixtures in the room. Additionally, modifications may be necessary for the doors, baseboards and trim in the area where tile is added. When applying the mortar, consider the height of the floor and avoid making it too thick.