Firebricks are heat-tolerant refractory bricks used to line the inside of most fireboxes. They protect the exterior of fire-burning stoves and retain heat to be released as the fire wanes.

Replacing broken or missing firebricks ensures the safe operation and prolonged life of a stove or fireplace.

Step 1: Allow the firebricks to cool completely once the fire has died out.

Step 2: Clear away ash and debris inside the box.

Step 3: Document the layout of the bricks. Photos, owner’s manuals or a hand-drawn pictorial record of the bricks will help mitigate frustration when installing the new brick. Numbering the bricks with a marker may also help.

Firebricks protect the exterior of fire-burning stoves and retain heat to be released as the fire wanes.

Step 4: Firebricks on the floor lining that are in good shape, except for a few small cracks, may not need to be replaced just yet. Filling the cracks with ash can provide enough insulation to protect the firebox. Ash does not retain heat, though, so the bricks will eventually need to be replaced for optimal efficiency.

Step 5: Firebricks lining the walls of the firebox can be temporarily repaired with refractory cement. Patches are typically short-lived in wood-burning stoves, as the impact of logs being added to the fire tends to knock the cement loose.

Step 6: Choose new bricks that are the same size and material as the old firebricks. Most firebricks are standard in length and width, but vary in thickness. Firebricks contain silica. Wear a respirator and safety glasses when working with firebrick.

Step 7: Close the chimney damper and remove the stove door to allow for easier access.

Step 8: Pry up the old firebrick and remove it from inside the stove. Clean away ash and debris beneath the brick. If the bricks are held in place by retaining clips or bars, loosen the bolts holding the clips before removing the bricks.

Step 9: Cut new firebricks to match the old bricks using a wet saw with a diamond blade.

Step 10: Install the new firebrick following the owner’s manual or previously created pictorial record. Firebricks should fit snuggly together. Use a wooden block and rubber mallet to wedge the bricks tightly into place.

Step 11: Fill gaps with cut pieces of firebrick and sweep ash into cracks and crevices.

Step 12: Reattach the stove door, open the damper and build a roaring fire for a toasty finish to the project.

— Have a home improvement question for the Fix-It Chick? Email it to Linda Cottin at features@ljworld.com.