DIY: How to Lay Tile Over Old Brick Fireplaces

Mix up Portland cement mortar to a smooth consistency and trowel it over the bricks. Use the flat edge of the trowel, rather than the teeth, to create a smooth surface. Fill in the mortar lines between the bricks themselves, and any irregularities in the surface of the bricks, leaving the area flat. Let the cement dry for at least 24 hours.

Measure the fireplace surround in sections, using a measuring tape. The top section above the firebox should extend past the firebox opening on either side, with the bottom of this section flush to the firebox opening. The two legs, or sides of the surround, should butt into this section. Measure them separately in case of size differences.

Re-create the fireplace surround's measurements on the floor nearby. Lay out the tiles that will cover the surround in this area to check fit and make necessary cuts. Lay the first tile directly above the firebox opening in the center of the surround. Use this tile as the starting point and install the other tiles so they radiate out from it. Make cuts on a tile wet saw and double-check their fit in this layout before installing.

Spread a small amount of Portland cement onto the fireplace surround directly above the center of the firebox. Rake this layer of cement with the teeth of the trowel until the cement is an even depth with the depth of the teeth. Install the first tile here, twisting it slightly into place. Lay the rest of the tiles in the same order you laid them on the floor. Wait 48 hours for the cement to dry.

Spread the grout over the surround with a rubber grout float. Hold the float at an angle to the surround to drag the grout over the tiles and press the float flat to the surround to pack the grout between the tiles. Wipe the tiles clean with a slightly damp sponge.