What It Does

The smoke chamber sits right above your fireplace, between the firebox and the flue. Think of it as the funnel that guides smoke up and out of your home. When it’s smooth and properly shaped, smoke moves quickly through. When it’s rough or cracked, it slows down, cools off and leaves behind a sticky mess of creosote.

A rough or damaged smoke chamber doesn’t just waste heat; it increases the risk of smoke backing up into your living room or, worse, a chimney fire.

What Can Go Wrong

You might notice:

• A strong smoky odor that lingers even when the fire’s out

• Excess soot or dark stains near the top of the fireplace

• Difficulty getting the fire to draw properly

• An inspection report noting “corbelled” (stair-stepped) brickwork
  

That jagged, stair-step brick design was common decades ago, but it traps smoke and encourages creosote buildup.

How the Pros Fix It

Today’s chimney pros can seal and smooth the smoke chamber using specialized materials that stand up to extreme heat. A popular choice is HeatShield ® Cerfractory Foam Smoke Chamber Sealant, a high-temp, expandable foam that coats the walls and fills cracks to restore a smooth surface.

Some professionals also use HeatShield ® PriorFire Formula 51, a refractory mortar, which can also be applied to the smoke chamber to reduce turbulence inside the smoke chamber, improving draft and reducing creosote buildup.

If creosote has already built up, your sweep might use products like PCR, Cre-Away, or ACS to break it down and make cleaning safer and easier.

The Products They Trust

Formula 51: Reduces turbulence caused by uneven smoke chamber surfaces, helping smoke rise smoothly.

HeatShield ® Cerfractory Foam: A high-temp, expandable foam that seals cracks and smooths rough brickwork, restoring the integrity of the smoke chamber.

PCR: A breakthrough cleaner that removes hardened, third-degree glazed creosote from flue tiles and stainless liners.

Cre-Away: Converts heavy creosote into a brittle form that breaks away during heating and cooling cycles, making it easier to remove.

ACS: An anti-creosote spray that helps prevent buildup and makes chimneys safer and easier to clean