There are plenty of ways to breathe new life into an old fireplace, such as installing a gas-burning insert. But that’s only the case if the firebox is safe. When a homeowner faced an issue of a crumbling and cracking firebox, he called Mason Mark McCullough for the job.
How to Repair a Firebox
- Start by protecting the furniture and textiles in the room by covering them with plastic sheeting or drop cloths. Lay another drop cloth over the hearth to protect it.
- Remove the cracked block and concrete. It’s best to use your hands whenever possible to avoid accidentally damaging the damper above the firebox.
- Clean out any branches, leaves, and other debris that might’ve collected behind the fire brick. Use a vacuum fitted with a HEPA filter to remove the soot and ash from around the firebox. Remove as much as possible.
- Lay out the new fire bricks. Create a running bond by staggering the joints between the courses. Remove the bricks once the overall layout works.
- Mix mortar until it’s the consistency of oatmeal. Lay a bed of mortar on the floor of the firebox and install the first course of bricks. Be sure to put plenty of mortar on the head joints for a proper installation, and continue the following courses. Smooth the joints with a brick jointer. Note: Pre-wet the bricks before their final installation by submerging them in water.
- Finish the firebox by installing the Franklin Curve. This is a course of bricks that slopes forward, pushing the heat into the room. Install these bricks vertically and lean them forward into a bed of mortar.
Resources
To prep the space, Mark lays out plastic sheeting over large furniture and a drop cloth in front of the firebox. To remove the old concrete and firebrick, Mark begins prying it out with his hands. He then cleans out any branches or broken masonry and uses a vacuum to remove the soot.
Mark will use yellow fire brick for the new firebox, as it best matches the original. He then lays the mortar using a masonry trowel. Mark adjusts his technique as he lays bricks on the Franklin Curve, carefully setting them at a forward-facing angle. He then smooths out the mortar joints using a brick jointer.
