All About Your Smoke Chamber & How It Functions
For many homeowners, the interior of a working chimney is a mystery shrouded in darkness. You light the fireplace, and the smoke goes up the chimney, right? Well, not quite. Along the way, it passes through an inconspicuous, but rather an essential component that is known as the smoke chamber.
The smoke chamber is positioned below the flue liner just above the chimney throat and damper assembly. It is critical for venting smoke and gases up the flue and out the chimney. It is typically constructed with a broad base that narrows into the throat as it passes through the smoke shelf. An improperly sized or built smoke chamber can choke the flow of smoke going into the chimney, causing it to back up into your living space.
The smoke chamber should be inspected regularly for potential problems. For the chimney to vent properly, the walls of the smoke chamber should have a smooth surface, according to the Chimney Safety Institute of America (CSIA). In older homes, the smoke chamber may have been constructed with standard or corbeled bricks rather than the more durable firebrick. It may have an irregular or rough surface. The intense heat from the fire can cause standard bricks to deteriorate and interfere with the proper venting of the chimney. It can even allow smoke and heat to transfer to the exterior walls compromising the structural integrity of the chimney.
Problems in the smoke chamber can also occur due to poor construction. Cracks or gaps in the masonry, which may not be easy to spot, can allow smoke and heat to enter, degrading the bricks even further. Parging the smoke chamber is recommended to repair these issues and prevent more expensive repairs in the future.
When is Parging Necessary?
If you experience frequent backdrafts, it could be a sign that your smoke chamber requires repair. Whether you have an older home or your smoke chamber needs repair, parging will fix these issues and bring it up to current building codes.
When parging the smoke chamber, your chimney professional will use a refractory mortar to smooth and seal the masonry surface. In severe cases where the bricks have deteriorated beyond repair, the interior walls will need to be rebuilt. Refractory mortar is used on the interior walls of the chimney due to its strong resistance against high temperatures. The smooth refractory surface allows the smoke and fumes to vent through the flue unobstructed without damaging the interior walls.
The best way to determine if your smoke chamber requires parging is with a thorough chimney inspection. During the examination, a qualified chimney sweep will examine the smoke chamber to look for signs of damage. If the smoke chamber has been compromised, parging will likely be the recommended solution.
Benefits of Parging
Parging uses refractory mortar in the smoke chamber to insulate the walls and protect the surrounding bricks from the high heat of burning logs in the fireplace. The smooth, heat-resistant surface encourages better airflow, reduces dangerous backdrafts, and improves the efficiency of your chimney.