Brick Fireplaces in Murfreesboro, TN

The parts of a masonry fireplace, and why they matter

A true masonry fireplace is a stack of parts that each have a job. The footing carries the weight. The firebox holds the fire and radiates heat back into the room. Above it the throat narrows, the damper closes the flue when nothing is burning, and the smoke shelf turns downdrafts back up. The smoke chamber then funnels everything into the flue, and the hearth extension protects the floor in front.

Get one of those wrong and the whole thing works badly. A smoke chamber with rough, stepped brick left unparged will drag on the rising gas. A throat set too wide will not accelerate the smoke. This matters when people ask why a beautiful fireplace smokes, because the answer is almost never the brick you can see. It is nearly always the geometry hidden behind it.

• Footing sized for the mass of the whole structure
• Firebox laid in firebrick with refractory mortar
• Throat and damper sized to the fireplace opening
• Smoke shelf and a smoothly parged smoke chamber
• Flue sized in proportion to the opening area
• Hearth extension in front of the firebox opening

Firebrick, refractory mortar and ordinary brick

The inside of a firebox is not built from the same material as the outside of the house. Firebrick is dense, low in iron and made to take repeated heating and cooling without breaking down. Regular face brick and ordinary Portland mortar in that position will crack, crumble and drop out over a few seasons of real fires. If you can see sandy joints and gaps in your firebox, that is usually what happened.

Refractory mortar is the other half of it. It stays intact at temperatures that would powder standard mortar, and joints in a firebox are laid tight and thin on purpose so there is as little mortar in the heat as possible. When we rebuild a firebox, it comes back in firebrick with refractory joints, because anything else is a repair with a short calendar on it.

• Firebrick rated for direct fire exposure
• Refractory mortar rather than standard masonry mortar
• Thin, tight joints to keep mortar out of the heat
• Correct splay on the sides to throw heat into the room
• A sloped back wall that helps drive smoke into the throat

Repairing a firebox versus rebuilding one

Not every cracked joint means a rebuild. Where the firebrick is intact and only the joints have opened up, we can rake them out and repoint in refractory mortar. That is a contained job and it buys years. It is worth doing before the gaps get wide enough to expose the masonry behind the firebrick.

Where the units themselves are cracked through, spalling off in layers, or where the back wall has bowed, the firebox comes out and goes back new. It is the honest call. We would rather rebuild a firebox once than repoint a failing one twice, and we will always tell you plainly which category yours falls into after we look at it cold and clean.

• Open joints with sound brick, repoint in refractory mortar
• Cracked or spalling firebrick, rebuild the affected walls
• A bowed or bulging back wall, full firebox rebuild
• A rough or unparged smoke chamber, parge and smooth it
• A damper that will not seal or has warped, replace it

When smoke comes into the room

Smoke rolling out of the opening has a handful of usual causes, and they get worked through in order. Flue area too small for the size of the opening is the classic one, and it is common on fireplaces that were widened at some point without touching the flue. A rough smoke chamber, a blocked or partly closed damper, or a flue that does not run high enough above the roof will each do it too.

The house itself can also be the problem. Tight modern construction, a running range hood or a basement returning air can pull the room negative so the flue has nothing to draw. A cold flue on the first fire of the season behaves the same way until it warms. We check the simple things first, because a smoke guard or a corrected damper is a great deal cheaper than opening up masonry.

• Opening too large for the flue area serving it
• Rough, stepped or oversized smoke chamber
• Damper warped, obstructed or not opening fully
• Flue not terminating high enough above the roofline
• Negative pressure in the house from exhaust fans
• Cold flue at start-up, cured by warming it before lighting

Outdoor fireplaces in a freeze-thaw climate

An outdoor fireplace is a chimney with a patio attached, and it gets none of the protection an indoor one enjoys. Rain lands on it, snow melts into it, and every hard freeze between December and February works on whatever water is inside the masonry. Build one like an interior fireplace and it comes apart in a handful of winters.

So the details change. The footing goes below frost depth on undisturbed soil or on rock, and around here shallow limestone can decide where the structure sits. Hearth and cap surfaces get sloped to shed water, not left flat. We use dense units and a mortar suited to exposure, cap the flue, and think about where water leaves the structure at every horizontal surface. A cover over the winter helps a great deal too.

• Footing below frost depth, on undisturbed soil or bedrock
• Dense, exposure-rated units rather than soft interior brick
• Every horizontal surface sloped to drain
• A capped flue so rain does not soak the stack from inside
• Drainage at the base so the structure does not sit in wet soil
• A cover or closure through the coldest months

Facing, hearths and mantels

The visible face is the part you live with, and it is the easiest part to change without touching how the fireplace works. Refacing an existing masonry fireplace in new brick or stone is common and usually straightforward, provided the structure behind is sound and the added thickness has been thought about at the hearth and at the mantel.

Hearths get built raised or flush depending on the room, and the hearth extension in front of the opening has to give proper clearance to combustible flooring. Mantel heights and depths also have clearance considerations. Requirements vary, so if you are altering an opening or adding a wood mantel to an existing fireplace, confirm what applies with the Rutherford County building department before we build it.

• Refacing brick or stone over a sound existing firebox
• Raised hearths, flush hearths and full-height surrounds
• Herringbone, soldier course and stack bond detailing
• Cast stone or brick mantel shelves and corbelled supports
• Matching an interior fireplace to existing house brick

Cost drivers and what to expect on site

A firebox repoint and a full outdoor fireplace live in different worlds, and pricing follows scope more than anything else. Indoors, the cost drivers are access, protection of the room, whether the flue needs work and how much of the structure is coming out. Outdoors, the footing and the site do a lot of the driving, because excavation onto rock or a long carry from the driveway adds days.

On site, expect protection first. Floors, furniture and paths get covered before demolition starts on an interior job. Masonry demolition is dusty and there is no way around that, but containment and a clean-up at the end of each day are on us. Interior work also carries on through winter, while an outdoor build usually waits for weather warm enough for mortar to cure properly.

• Scope, from repoint to firebox rebuild to a new structure
• Access, protection and the amount of demolition involved
• Whether the flue or damper needs work at the same time
• Site and excavation conditions on an outdoor build
• Material selection, from standard brick to cut stone
• Season, since mortar work needs temperatures above about forty degrees