Your fireplace may not be safe if it has broken or cracked bricks in the fireplace wall that will allow smoke and fumes from the fire to escape into your home. To ensure the safety of your family and guests, you should repair these bricks. To accomplish this, you'll need a few special tools, the right material, and an understanding about how to remove and replace your damaged brick.
Step 1 – Removing the Old Brick
Use your hammer and a chisel to chip out the old mortar around the brick you'll be replacing. Be careful not to damage other adjacent brick. Once you've chipped away all the mortar around the old brick, the brick should be loose enough that you can remove it by hand. Take it out of the wall and set it aside.
Step 2 - Acquiring Your Replacement Brick
If your fireplace bricks are a uniform color and are all unpainted, you'll want to replace your broken bricks with bricks of the same color. To ensure that you match the color of the bricks you are replacing, be sure to take a large piece of a brick with you to the merchant when you purchase your replacement brick. Be sure your replacement brick is fireclay brick.
Step 3 – Preparing the Space Created by the Removed Brick
To ensure that your new brick mortar will properly adhere to the new brick, brush out all debris from the space you created from removing the old brick. If necessary, use a vacuum cleaner. Before you can apply grout to the brick, the surfaces of the brick that receive your mortar must be wet. This includes the new brick and the old bricks surrounding the new brick. Use a spray bottle of water to moisten all these surfaces.
Step 4 – Apply Mortar
Make a mixture of sand, water and fireplace cement. Trowel this mortar onto the sides of the brick in the space where you'll insert your new brick. Be sure you leave enough space for your new brick to fit. Apply a thin layer of mortar to the new brick.
Step 5 – Fitting Your New Brick into Place
Wrap two pieces of string around your new brick, one on each end of the brick. Leave enough length that after the brick is in place, the ends will be exposed and you will be able to grip them. Slide your new replacement brick into the space created by removal of the old brick. Try to avoid pushing the brick too far into the wall.
Step 6 – Leveling Your Brick
Once your brick is in place, be sure it is level and even with the surrounding brick surface. If it is pushed too far into the wall, pull it back out by gripping the ends of the strings and pull them toward you until the brick surface is even. When the brick is straight and level, remove the string from the brick by pulling the loose end of the string.