How to Build a Non-Combustible Fireplace Surround

Place a strip of masking tape along the edges of the fireplace mantel to protect the surface form the materials used to adhere the surround in place. Set a dropcloth at the base of the fireplace to catch any debris.

Mix thinset mortar in a bucket with a mixing paddle attached to a drill. Pour latex additive into the mix while combining the mortar with water to make the mortar more flexible. Follow the additive manufacturer’s instructions for the amount of additive to add according to the amount of mortar mixed. Add water to the mortar until you have a mix of the same consistency as peanut butter.

Spread the thinset over the brick surface, filling the joints of the brick and creating a thin flat layer of the mortar. Use a finishing trowel to spread the mortar, and then allow the mortar to cure overnight.

Measure the firebox opening with the tape measure and divide the distance in half. Place a mark at the halfway mark extending upward from the top of the firebox over the mortar covering the surround. Use a pencil to mark the surround with a straightedge to keep the mark straight.

Cut a 1-by-3-inch board to the measured length of the firebox plus an additional 6 inches. Place the board across the top of the firebox, with the top of the board running flush with the base of the surround above the firebox and centered over the firebox opening. Secure the board in place using 2-inch masonry screws driven through the board and into the brick beneath at each end of the firebox opening with a drill containing a screw set. This board will serve as a base for your tiles placed onto the upper portion of the surround.

Mix a second batch of thinset with latex additive. Spread the thinset onto the top of the surround above the wood board using the notched trowel. Tilt the trowel on end and use the notches on the edge to create grooves in the mortar to better grasp the rear of the tiles. Place the first tile on the centerline drawn on the surround, with the tile centered on the line and the bottom of the tile set against the board.

Press the tile onto the mortar with a small twist. Place a tile spacer onto either side and on top of the tile. Set another tile in the same row next to the center tile, continue to set tiles on the row, placing spacers between each until you reach the edges and no full tile will fit. Cut a full tile to fit the space along the edge using a wet saw, and then set the partial tile in place. Position the partial tile so that the cut edge of the tile is against the mantle for less visibility of the cut. Place the nest row of tiles above the first, using the spacers to keep all the lines uniform. Continue placing each row until you reach the top of the surround space. Cut the tiles along the top as needed to fit the space.

Remove the support board by unscrewing it. Measure the height of the tiles and the space of a joint created by the spacers. Measure the height of untiled space down the legs of the surround on either side of the firebox opening. Divide the height by the combined tile and joint line measurements to determine the number of full-sized tiles needed to cover the space. For example, if you have legs extending 4-feet beneath the tiles section and the combined tile and joint line measurement is 3-1/2 inches you’ll have 13 full-sized tiles with space left over for a partial tile that’s 2-1/2 inches high.

Cut the partial tiles for the bottom row of the surround feet using the wet saw. Spread mortar along one of the legs and then beginning with the bottom row of cut tiles, apply the tiles from the bottom upwards. Use tile spacers to keep the spacing between the tiles even, and place the cut side of the partial tiles against the fireplace hearth. Work in rows until you reach the tiled section above the surround. Repeat the tiling process for the other leg.

Allow the mortar holding the tiles to cure overnight.

Remove all spacers. Mix a batch of grout in a bucket. Spread the grout into the tile joints with a rubber grout float. Use the edge of the rubber float to slide the grout over the tile and into the empty joints. Wipe the tiles immediately after grouting with a damp grout sponge, removing the excess grout that did not go into the joints. Wait two hours, and then wipe the area again with a cotton cloth to remove any grout that may otherwise form a gray haze.

Remove the masking tape from the mantel. Allow the mortar and grout two weeks to cure before using the fireplace.