A very small portion of the chimney system is accessible without the help of special equipment or cameras. One of the difficult to see – yet extremely important – components of the chimney is the smoke chamber.

What is a smoke chamber? Smoke chamber parging image - Seattle WA - Pristine Sweeps

Located directly above the firebox, the smoke chamber is designed to help the fireplace draft correctly. Smoke, gas, hot air, and other byproducts of combustion flow up and into the smoke chamber before they are funneled up the flue and out of the chimney.

Most older homes with masonry fireplaces have smoke chambers that were built with a technique known as corbelling. This building technique uses stacked bricks to create jagged steps as the smoke chambers narrows up to the flue; while this quick and easy building technique is effective, it has several design flaws that make it unsuitable for long-term use.

Smoke chamber repair and parging

The jagged steps of a corbelled smoke chamber have a number of exposed masonry joints and create plenty of nooks and crannies for the accumulation of soot, ash, and creosote. If your smoke chamber was constructed using the corbelling technique, the jagged masonry steps can be covered to create a smooth surface. Known as parging, this technique repairs smoke chambers by covering the jagged, staggered steps with a single, solid, smooth surface.

There are two main types of parging technique: cast in place and spray on. A cast in place restoration involves adhering the product directly to the corbelled masonry. Cast in place parging is also a good way to reinforce the structure of the smoke chamber. Spray on products are equally effective and can be easily sprayed onto the masonry in the smoke chamber to create a smooth surface.

Why parging is important

Because the smoke chamber is not seen, parging is not a cosmetic repair; it is important to the safety, drafting, and functioning of your fireplace system. The following are four reasons why having your smoke chamber parged is important.

  1.  Improved safety and efficiency when venting. With fewer cracks, edges, and corners, smoke and gas can easily flow up, through, and out of the smoke chamber.
  2. Reduce creosote and soot buildup. Creosote is extremely flammable, and excessive buildup of it in your smoke chamber and chimney can significantly increase your risk of accidental chimney fire. With fewer corners and joints there is a smaller surface area for creosote and other byproducts of combustion to accumulate.
  3. Reinforce masonry joints. The corbelled design of many smoke chambers has dozens of masonry joints; over time, smoke, gas, and heat can weaken these joints. Having the smoke chamber parged reinforces these joints and makes the smoke chamber structurally stronger.
  4. Extend the lifespan of the fireplace system. Having the smoke chamber parged meets modern building standards, makes the fireplace safer to use, and can help the entire chimney system last longer.

Parging your smoke chamber is a necessary repair. Having the smoke chamber parged can make your fireplace burn more efficiently – as well as significantly improve the safety of your fireplace system. For more information about smoke chamber parging or to schedule an inspection of your smoke chamber, contact Pristine Sweeps today!