An easy and effective way to install tile over a brick fireplace is to level out the brick surface with thinset mortar, and apply the tile directly to the cement. There are other options, but thinset mortar dries quickly and is simple to use.
- Prepare the fireplace
Before you begin, clear all objects from the top of the mantle and store them in a safe location. Remove any mantle and other items attached to the brick. This includes baseboard trimming, hooks or other decorative finishes. Cover the hearth with a strong tarp or drop cloth to protect it from damage. Use tape to create a seal and keep the cloth from moving while you are working.
- Clean the brick
Using a wire brush, scrub the entire surface area of the fireplace to break up and remove any loose mortar. Soak a rag with white vinegar and clean the entire fireplace to remove dirt, soot and fine powder created by the wire brush. Let the bricks dry completely; this will take a day or two.
- Cover the brick with thinset
In a large bucket, combine water and thinset powder until it is smooth and creamy. Joe Ferrante of "This Old House" recommends using a white, latex-modified thinset. If your tiles and grout are darker, choose a gray or colored thinset. Use a flat trowel to spread the thinset onto the brick fireplace in long even strokes. Make sure you get the cement into the grout joints. Apply a second coat if needed to even out the surface and make it flat and smooth. Let the thinset dry overnight.
- Prepare the tiles
Prior to applying the tiles, lay the tiles out in the desired design. Cut any tiles to fit the shape and size of the fireplace.
- Apply the tiles
To create the bond between the tile and the concrete, apply another thin layer of thinset mortar. This time, use a notched trowel to create lines in the cement. Adhere the tile to the wet cement in the correct pattern. Pay attention to the space between the tiles to ensure even grout lines. You can also use a level or a straight-edge to keep your lines even during the application process. Allow the tile dry overnight.
- Grout the tile
Mix the grout until it is smooth and free of lumps. Place a small amount of grout onto your grout float and apply it diagonally across the newly tiled surface. Use a wet rag or sponge to remove any excess grout from the tiles. Let the grout cure for at least four hours.