How Do You Make a Fireplace Hearth?

Remove the old hearth using a demolition hammer fitted with a chisel bit while wearing goggles. If you're installing a new fireplace that doesn't already have a hearth, mark out the area with a tape measure. Remove the existing flooring in that area.

Measure the depth of the material you plan to use on the hearth, such as tile. Add 3/8 inch to account for the thinset you will use to adhere the tiles. You want the concrete base for the hearth to be lower than the rest of the floor by this measurement. For example, if the tile is 1/2-inch thick, you would add 3/8 inch to get a total of 7/8 inch so the top of the concrete pad should hit at 7/8 inch below the rest of the floor.

Lay a 2-by-4-inch board that is longer than the hearth opening flat on a workbench or other surface. Measure up from the bottom of the board on the 4-inch side the same distance you want the hearth pad to end up below the floor level. For example, you would cut notches out of both edges that are 7/8 inches. Mark this measurement on both ends of the board on the 4-inch side. Draw a line from the 7/8-inch spot over to the end of the board to mark a rectangular cutout that creates a ledge or notch to keep the board level against the existing floor. The lower portion of the board should fit down into the hearth area with enough room to move the homemade screed side-to-side.

Mix concrete according to the package directions. Pour the concrete into the hearth area, getting an even layer throughout. Place the board down in the concrete and move it side-to-side as you move it forward and backward over the concrete to smooth it. Add more concrete as necessary.

Use a trowel for additional smoothing of the concrete. Allow the concrete to dry overnight once you get it smooth.

Spread thinset over the concrete hearth pad. Pull the notched edge across the thinset to make grooves running parallel to the fireplace.

Place tiles in the thinset, using spacers to keep the tiles even. If you're using a slab of stone, position it over the opening and press down to set it. Leave the hearth covering overnight to set.

Grout the hearth if you used tiles for the flooring. Spread the grout over the cracks in the hearth tiles using a grout float. After it rests for 20 to 30 minutes, wipe off the tiles with a sponge.

Grout where the tile meets the flooring if the rest of the room is wood. A wood edging piece is also an option. If the room is carpeted, you may not need a edging piece because the carpet should cover the transition.