How to Repair a Damaged Fireplace Brick
Ask This Old House mason Mark McCullough replaces a chipped brick in a fireplace surround
- Prep the surrounding work area by hanging plastic drop cloths. Tape them to any door, window, and hallway openings with painters’ tape.
- Put the canvas drop cloth down immediately underneath the work area.
- Use the grinder to cut the damaged brick out of the fireplace. Cut just on the inside of the bed joints to ensure the rest of the bricks are not disturbed. This will be really dusty, so use dust-collection tools to keep the dust down as much as possible.
- Chisel out the head joints with a hammer and chisel.
- Once the mortar has all been loosened, chisel away at the brick using the larger masonry chisel until it’s completely out of the fireplace. Try to break the brick in key areas so that it comes out easier.
- Dampen a masonry brush and clean out the hole where the old brick was to ensure the new brick will bond.
- Mix up some Type N mortar in a bucket with some water using the trowel until the mortar is an oatmeal consistency.
- Scoop out some mortar with the trowel and lay it flat on the hole where the old brick used to be. Smooth it out with the trowel.
- Fill the head joints or back butter the bricks with mortar. This is the best opportunity to ensure a nice, full joint of mortar.
- Wiggle the replacement brick into place.
- For the top head joint, add mortar the same way you would if you were repointing. Take a scoop of mortar and then, using a tuck pointer, push the mortar off the trowel and stuff it as deep into the joint as possible. Repeat this process until the joint is full.
- Once all the mortar is in place, clean up the joints by dragging a jointer along all the new mortar lines. Pick a jointer that best matches the look of the rest of the fireplace (in this case, a concave jointer).
Working with masonry can be dusty, and the silica dust produced by working with it is hazardous to your health. To minimize the dust, Mark recommends hanging up plastic tarps around the entire work area to confine it to one space, and he also recommends using dust-collecting tools. The grinder and HEPA vacuum Mark used on this project are both manufactured by Bosch.
The hand tools Mark used on this project, including the chisel, hammer, trowel, and mixing bucket can be found at home centers. The replacement brick Mark used can be found at local masonry yards.
Mark used a Type N mortar to secure the new brick in place, which is manufactured by Quikrete.