How to Make a Red Brick Fireplace Hearth

Free up the area around the fireplace so that you have at least 16 inches of space in front of the fireplace and 8 inches on either side. For fireplaces with an opening larger than 6 square feet, the space for the hearth needs to extend 20 inches out and 12 inches on either side.

Place the first layer of fireproof millboard down as the base of the hearth in front of the fireplace opening, using a bead construction adhesive around the edge. You do not have to remove the existing hearth, if you want to use it as an extra fireproof layer.

Cut a sheet of 26-guage steel to fit the space for the hearth using aviation snips. Place the steel on the floor and use a bead of construction adhesive around the outer edge to hold the sheet in place. The weight of the bricks will anchor everything to the floor.

Lay the brick for the hearth without using any mortar. Cut any brick for the edges or corners by scoring them first with a chisel and then hitting the brick solidly with a hammer. Take the bricks to the back of the fireplace for a solid surface, arranging them to fit neatly with the space of the hearth. Number the cut bricks with a pencil for later reference. Remove the bricks to the side.

Apply a layer of mortar over the steel plate using a 5/16-inch notched trowel. Work over a small area at a time, starting at the back of the fireplace. Spread a layer of mortar over the base and sides of the bricks, using the notched trowel and press lightly into place using a rubber mallet. Leave a 1/4-inch gap between the bricks. Remove any excess immediately.

Dry the brick hearth overnight. Trim out the edges of the bricks with wood trim, nailing each section in place to the floor with 2-inch trim nails.