The contractor that poured the concrete floor did his best to keep it level, and for most flooring applications, such as carpet, linoleum and laminate, it is sufficient. Ceramic tile, on the other hand, requires a very level base surface or the tiles will crack under the pressure of everyday use. A concrete subfloor is the best surface on which to install ceramic tile. Before beginning any tile installation the concrete must be leveled and prepared. The process is simple and requires little specialized training or equipment.
- Broom
- Mop and mop bucket
- Level (4 to 6 feet in length)
- Pencil
- Floor grinder (if needed, it can be rented)
- Floor leveling compound
- 5-gallon bucket
- Drywall compound mixer
- Drywall knife (12 to 24 inches wide)
Preparation
Remove any foreign material from the concrete. Concrete must be completely free from any dirt or chemicals (oil, paint, glue, etc.) or the ceramic tiles will not properly adhere to it. It is necessary to sand the floor to remove carpet glue and paint, or if it is new concrete which has a chemical sealer.
Clean the concrete surface thoroughly by sweeping and mopping.
Check the floor for high and low spots using a 4- to 6-foot level by systematically moving across the floor with the level.
Mark the floor with a pencil to indicate low spots. Draw a circle around the areas in question. These areas will need to be filled with floor leveling compound.
Use an electric floor grinder to take down any high spots. Be careful not to remove too much material.
Level the Floor
Mix some of the floor leveling compound in a 5-gallon bucket until it is the consistency of pancake batter. Mix thoroughly until all lumps are gone.
Apply floor leveling compound to the low spots. Use a 12- to 24-inch drywall knife to spread the compound over the marked area. This step is being done correctly if there is no excess compound left on the floor. Otherwise, it will need to be sanded off.
Allow the treated area to dry and repeat this process as needed until all of the marked areas are filled in.
Check the level of the floor again. Some areas may require a second application of compound before they are completely level.
Sweep and mop the floor again before installing the tile.
Tips and Warnings
- Mix the floor leveling compound in small amounts because it sets up fast. This will prevent waste.
- Always clean the bucket and mixing paddle before mixing a new batch of compound.
- Clean excess compound from the knife before smoothing the compound on the floor.
- Never add more water to compound which is beginning to set up. Throw it out and mix up some more.
