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What firebox repair covers
The firebox is the box the fire sits in. It takes the most heat of any part of the fireplace, and it shields the framing, walls and smoke chamber around it. In a masonry fireplace it is built from firebrick set in refractory mortar, materials made to handle high heat. In a factory-built (prefab) fireplace it is usually lined with molded refractory panels instead.
Firebox repair restores that heat-resistant lining. It can mean repointing failed mortar joints, replacing individual cracked or spalled bricks, rebuilding a back wall or side wall that has come loose, or replacing worn refractory panels in a prefab unit. If the problem turns out to be somewhere else in the fireplace, such as the damper, smoke chamber or doors, our fireplace repair service handles those parts too.
Signs your firebox needs repair
Firebox damage is easy to miss because soot hides it. Look closely with a flashlight while the fireplace is cold and clean.
Signs worth getting checked
- Mortar joints that are recessed, crumbling or missing, leaving gaps between bricks
- Firebrick that is cracked through, flaking or breaking off in layers (spalling)
- Loose bricks, or a back wall that leans or bulges toward the room
- Cracks in refractory panels that are widening, or pieces breaking off
- Pieces of brick, mortar or panel showing up in the ashes
- Surrounding walls or the mantel area feeling hotter than they used to when a fire is burning
Gaps are the real concern
A crack or open joint in the firebox can let heat and embers reach the wood framing behind it. If you can see gaps that go through the lining, hold off on fires until the firebox has been looked at.
Smoke rolling into the room is a different issue from a damaged firebox. That usually points to a draft problem, which our fireplace draft repair work addresses.
Masonry fireboxes and prefab fireboxes
| Feature | Masonry fireplace | Prefab (factory-built) fireplace |
|---|---|---|
| Lining | Firebrick laid in refractory mortar | Molded refractory panels |
| Typical repair | Repointing joints, replacing bricks, rebuilding a wall | Replacing cracked or crumbling panels |
| Materials used | Heat-rated firebrick and refractory mortar | Replacement panels that fit the unit |
Lining
- Masonry fireplace
- Firebrick laid in refractory mortar
- Prefab (factory-built) fireplace
- Molded refractory panels
Typical repair
- Masonry fireplace
- Repointing joints, replacing bricks, rebuilding a wall
- Prefab (factory-built) fireplace
- Replacing cracked or crumbling panels
Materials used
- Masonry fireplace
- Heat-rated firebrick and refractory mortar
- Prefab (factory-built) fireplace
- Replacement panels that fit the unit
We also work on gas fireplaces, and on all major brands of fireplaces in general. When a prefab unit is too far gone for panel replacement, we can talk through replacing it; our fireplace installation service covers putting in a new one.
What the visit involves, step by step
From first look to finished repair
Inspect the firebox
We clean off enough soot to see the real condition of the brick, mortar or panels, and check the surrounding parts of the fireplace for related damage.
Explain what we found
You get a plain description of the damage and the repair it needs, along with a free estimate, before any work starts.
Remove the damaged material
Failed mortar is cut out, broken bricks are taken out, and worn panels are removed, so the repair goes onto sound material.
Rebuild the lining
New firebrick and refractory mortar go in for masonry fireboxes; prefab units get replacement refractory panels.
Clean up and go over first use
We clean the work area and tell you how to handle the first fires after the repair so the new mortar can set properly.
Keeping a firebox in good shape
- Burn dry, seasoned wood and keep fires a reasonable size; very hot fires are hard on brick and mortar.
- Don't throw water on a fire to put it out; a sudden temperature change can crack firebrick and panels.
- Clear out ash regularly so you can see the floor and walls of the firebox.
- Have the fireplace inspected on a regular schedule so small mortar gaps are caught before bricks loosen.
Booking firebox repair
Get in touch to describe what you're seeing, and we'll set up a visit. Commercial and property-manager work is offered as well, for buildings with more than one fireplace to look after.
