How to Tile an Old Brick Fireplace

Cut cement backer board to fit the face of your fireplace, using a carbide-blade cutter. Mix thinset mortar, following the manufacturer's directions, and spread it with a 1/4-by-1/4-inch square notched trowel over the fireplace bricks. Place the backer board onto the fireplace and allow the mortar to set for 24 hours.

Lay out your fireplace tile design on the ground in front of your fireplace. Double-check your measurements and make any cuts necessary before starting the installation, using a tile cutter. Use curved bullnose tiles around the fireplace opening for a clean, finished appearance.

Spread thinset mortar on the backer board starting at the top of the fireplace, using the square notched trowel. Set the top tiles and support them with 6d nails hammered into the cement backer board.

Set the next row of tiles on the fireplace and hold them in place with masking tape. Use masking tape adhered to each tile to secure it to the tile above it. Repeat hanging your tiles until you reach the bottom of your fireplace. Allow the tiles and mortar to set for 24 hours.

Mix unsanded grout in a bucket with water until it reaches the consistency of peanut butter. Spread the grout with a grout float held at a shallow angle, pressing the grout into the joints between the tiles. Remove any access grout, holding the grout float at a steep angle, and wipe any grout residue from the tiles with a damp sponge.

Mist the grout several times a day for three days with plain water in a spray bottle. This damp curing process increases the strength of the grout as it cures.

Pour grout sealer into a shallow dish and spread the sealer over the surface of the fireplace, using a sponge. Use a soft cloth to wipe up any excess sealer.