DIY: How to Lay Tile Over Old Fireplaces

Lay a tarp on the floor around the fireplace to prevent getting any old material on the floor as you cover up the fireplace. Brush down the entire fireplace with a wire brush to remove any loose bits and pieces of stone or mortar.

Wipe down the bricks with a clean rag soaked in white vinegar, taking extra care on areas with soot to get the bricks as clean as possible. Allow the fireplace to thoroughly dry for at least 24 hours.

Mix the white latex thinset in a mixing tub according to package instructions. It should be a thicker consistency so it won't run down the wall. Apply it to the fireplace with a flat trowel, getting it firmly into all the grout lines between bricks. Allow the first coat to dry thoroughly, and then go over the entire fireplace with a second coat.

Place a 1-by-4 board across the top lip of the firebox to provide a secure ledge to place the front tiles on. The ledge ensures you keep tiles perfectly straight, and helps keep them from slipping down as the thinset dries. Nail the board to each end of the fireplace, using a hammer.

Mix another batch of thinset in a clean mixing tub. Apply the thinset to the top of the fireplace, using a notched trowel. Press tiles firmly into the thinset to reduce any air bubbles behind the tile. Add spacers between each tile to keep the grout lines as straight as possible.

Trim tiles as needed, using a wet saw. Work your way from the top of the fireplace down, doing the left leg of the fireplace and finishing with the right leg. Allow the thinset to dry according to package instructions, usually 24 hours.

Mix the desired grout color and apply it to the dried tiles with a 45-degree angle. Use enough grout to pack into the space between tiles but only leave a thin layer on the tile surface. Complete the entire fireplace.

Wipe down the tiles with a damp sponge once the grout becomes hazy on the tile surface. Avoid wiping too much out of the grout lines, but clean off the tile completely and smooth down any inconsistent grout lines. Allow to dry for 12 hours.