How to Install Fire Brick

Mark the fire brick panels with a pencil to indicate which pieces go on the bottom, back and sides of the fireplace. If your fire brick panels came in a kit, the instructions should indicate which pieces go where. If not, use measurements as your guide.

Lay the bottom fire brick panel. Wet the back of the panel and the bottom of the fireplace box with the sponge. Spread a thin layer of the mortar mix on the entire back surface of the fire brick panel with the masonry trowel. Press the fire brick panel in place with the bricks facing upward so they are visible to you and so the panel is evenly in the fireplace frame.

Install the fire brick panel that goes on the back of the fireplace box. Wet the top and bottom edge of the back fire brick panel. Spread mortar in a horizontal line at the top and bottom edge with the trowel. Press the panel in place at the back of the fireplace box. The fire brick panel will not sit flat against the wall; there will be a gap to account for the shape of the downdraft component of the fireplace system. Place a board against the panel to hold it in place while the mortar sets.

Install the side fire brick panel. Wet the back of the panel and the side of the fireplace box with the sponge. Spread a thin layer of mortar on the back of the side panel with the trowel. Set the bottom edge of the fire brick panel against the bottom edge of the side wall at an angle. Swing the fire brick panel inward until it sits flat against the wall. Tap the panel with a rubber hammer to secure. Place a board against the panel to hold it in place while the mortar sets.

Install the opposite side fire brick panel. Repeat Step 4, but work from the opposite direction.

Seal the seams between all the fire brick panels. Fill the mortar bag with mortar mix. Pipe the mortar mix along each of the seams, creating a tight seal.