Only a small portion of the fireplace and chimney are visible to the naked eye. Because of this, professionals often need special equipment such as closed-circuit cameras to assess the chimney system. One part of your chimney that is difficult to access yet extremely important is the smoke chamber.
What is the smoke chamber?
The smoke chamber is a small section of the chimney directly above the firebox. The purpose of smoke chambers is to improve fireplace drafting. Smoke, hot air, gas, and other byproducts of combustion pull up and into the smoke chamber before it flows up the flue and out of the chimney.
In many older homes, the smoke chamber was constructed using a technique known as corbelling. While corbelling is a quick, easy, and effective building technique, it has several key design flaws that make it difficult to clean and repair.
Parging smoke chambers
Smoke chambers built by corbelling are sturdy, but this construction method has one major drawback. The stairstep design has large numbers of exposed masonry joints and plenty of corners in which ash, soot, and flammable creosote can accumulate.
To correct this design problem, the jagged edges and corners in the smoke chambers can be smoothed in a process known as parging. During the parging process, the staggered, stairstep masonry is covered with a smooth, solid surface.
The two types of parging techniques
There are two different ways to parge your smoke chamber: cast in place or spray-on parging.
- Cast in place: In cast in place parging, the new masonry is applied directly to the existing corbelled masonry using special molds. This technique can also be used to help reinforce the structure of the smoke chamber if the fireplace is older or has been damaged.
- Spray on: Spray on parging is equally as effective as cast in place. It is applied by spraying the new surface directly onto the old masonry, creating a smooth surface free from joints.
Why is parging important?
The smoke chamber is an often forgotten chimney component. The following are three reasons why parging the smoke chamber is important.
- Reduce creosote buildup. Creosote is highly flammable. In a corbelled smoke chamber, there are plenty of unreachable corners where creosote can accumulate. Parging the smoke chamber can help reduce creosote buildup, as there are fewer corners and joints where it can accumulate.
- Improve safety and efficiency. With fewer masonry joints and corners, smoke, gas, and other byproducts of combustion can safely and efficiently vent up and out of the fireplace.
- Reinforce masonry. The masonry joints in a corbelled smoke chamber are at risk of deteriorating due to exposure to heat over time. Parging the smoke chamber can help reinforce these joints and strengthen the structural integrity of the chimney.
If you have an older home with an original masonry fireplace, you should get the smoke chamber parged, as this makes your fireplace safer and more efficient. For more information about smoke chamber parging, contact Coopertown Services today!