Firebox and Smoke Chamber Repair in Seattle

The firebox is the brick-lined box where the fire burns. Its firebrick and the special mortar between it take direct flame for hours at a time, and in older houses that mortar has often worn out of the joints. Behind and above is the smoke chamber, the sloped space that funnels smoke from the wide fireplace opening into the narrow flue. In many older chimneys it was built with stepped, rough brick that collects creosote and slows the draft.

Gaps in either one are a fire risk because heat can travel through to the wood framing around the fireplace. They also show up as smoke problems. We see both often in older Seattle and Tacoma houses, where many fireplaces date from before 1940 and have had decades of hot fires and decades of rain coming down an uncapped flue.

Signs you need this

• Cracked, loose or missing firebrick
• Mortar joints in the firebox that are empty or crumbling
• Rough, stepped brick visible above the damper
• Smoke spilling into the room even with the damper open
• Heavy deposits on the smoke shelf after a sweep

How we do it

1. Inspect with photosAt the free inspection we look at the firebox, damper, smoke shelf and smoke chamber and photograph the problem areas.
2. Repair the fireboxLoose or cracked firebrick is replaced and empty joints are filled with refractory mortar made for direct heat.
3. Parge the smoke chamberIf the chamber is rough or has gaps, we coat it with a heat-rated parging mix so it is smooth and sealed.
4. Check the draftWith the work cured, we check that smoke goes up cleanly and note the result on your report.

What does smoke chamber parging do?

Parging is a coat of heat-rated mortar applied over the inside of the smoke chamber. It fills gaps between bricks that could let heat reach the framing, and it turns rough steps into a smooth slope that smoke moves across more easily. Smoother surfaces also collect less creosote. Smoke chamber parging typically costs $800 to $2,000.

How does Seattle's chimney rule apply here?

Seattle's rule for repairing unreinforced masonry chimneys, Director's Rule 5-2004, says that structural work going below the top of the smoke chamber means rebuilding the smoke chamber and chimney to current code, with a permit at any cost. Firebrick replacement and parging are lining repairs, not structural rebuilds. If the inspection shows the masonry around the chamber itself has failed, we tell you, and suggest confirming current requirements with SDCI before any larger job.

What does firebox repair cost?

Repairing firebrick or mortar joints typically costs $300 to $1,000. Parging the smoke chamber typically costs $800 to $2,000. Rebuilding a firebox that is too far gone typically costs $1,000 to $2,500. The price depends on how much brick needs replacing and whether the fireplace will be used for wood, converted to gas or fitted with an insert.