Is Smoke Chamber Parging Necessary? Find Out Here!

Smoke chamber parging is important for your chimney to function properly. A smoke chamber should be in its optimal condition to provide an efficient chimney draft.

It is common for older chimneys to have a corbeled smoke chamber. Such a smoke chamber does not provide an adequate draft and increases the chances of creosote buildup. So, parging is done to make the smoke chamber walls smooth to provide efficient drafting.

Let us discuss smoke chamber parging in more detail so that you understand why it is so important to get your smoke chamber parged.

But first, let us talk about the different types of smoke chamber parging.

What Does It Mean to Parge a Smoke Chamber?

Smoke chamber parging means smoothening its surface. Parging can be done in two ways: spray-on parging and Cast-in-place smoke chamber parging.

• Spray-on Parging – In Spray-on parging, the chimney sweep sprays a new layer of coating to smoothen the smoke chamber surface. The coating is made from high-temperature refractory mortar and has an insulating effect. 

• Cast-In-Place Smoke Chamber Parging – The cast-in-place parging process involves applying new masonry over the corbelled sides of your smoke chamber. Through this method, you smoothen the smoke chamber while also providing structural strength.

The Smoke Chamber Parging Process

The smoke chamber parging process involves the following steps:

• Step 1. Cleaning
  You should clean the smoke chamber surface that you want to parge. This ensures strong bonding. You don’t want any loose mortar or soot on your surface. Use a stiff-bristle brush with water and detergent to brush off the unwanted materials off the surface.

• Step 2. Applying Water
  When a dry surface is parged, it absorbs the moisture out of the mortar. As a result, the mortar dries out and results in cracks and flakes. To avoid that, make sure you spray the surface with water.

• Step 3. Applying Mortar
  Now that your smoke chamber is clean and moist, apply the mortar. You can either do that by hand or use a mason’s trowel. Make sure that your mortar mixture is consistent and sticks when you throw it on the wall.

Spread the mortar using a sweeping motion. While sweeping, remember to apply a bit of pressure to make sure the mortar reaches the various curves of the surface.

When done, your parging should have a thickness of around 1/4″.

Is Chimney Parging Necessary?

The smoke chamber is essential to the proper drafting of your chimney flue gasses. It should be properly maintained and regularly cleaned. The NFPA 211 guidelines recommend smoke chamber parging to make its walls smooth.

If your smoke chamber is not parged, you could have the following smoke chamber problems:

Corbeled Smoke Chamber Walls

The walls of a smoke chamber resemble a reverse staircase. The bricks are stacked on top of each other to form an irregular structure. The irregular structure causes turbulence in smoke from the fireplace and results in a poor draft. A parged smoke chamber will have a smooth surface that will allow smoke to pass through easily. Thus, improving its draft.

Soot and Creosote Buildup

A smoke chamber that has not been parged has irregular or corbeled walls. Smoke takes more time to pass through such a structure. This increases the chances of the smoke cooling down in the form of soot and creosote buildup. Creosote buildup is dangerous because it can clog the chimney and prevent proper ventilation. It also increases the chances of a chimney fire.

A smoke chamber with smooth walls will not have a soot or creosote problem.

Crack Formation

Cracks can start to form in your smoke chamber masonry after a while. Smoke and other dangerous gasses can leak from these cracks and affect the chimney draft. Poor chimney draft means that the smoke and Carbon Monoxide (CO) can come back into your room. This can cause various respiratory issues and can even be fatal.

Parging your smoke chamber allows you to cover these cracks with new masonry and improve the structural integrity of your smoke chamber.

Heat Transfer

Parging has an insulating effect so the heat from the fire will not transfer to the surrounding walls. This also improves drafting since the air inside the flue will heat up faster.

Mold Issues

Without proper care, mold inside the fireplace can develop in these cracks and crevices, posing health risks and indicating moisture problems. Regular inspections and addressing any signs of mold are as important as mechanical repairs in maintaining a safe and efficient chimney system.

Inadequate Smoke Chamber Design

An inadequately designed smoke chamber can lead to poor smoke flow. Proper parging in the smoke chamber is essential, as it creates a smoother surface, enhancing airflow and smoke management. Thus, parging is not only beneficial but necessary for optimal fireplace performance. Parging is not just a beneficial practice. It’s a necessary step in preventing common issues associated, especially with double-sided fireplaces.

Signs My Chimney Smoke Chamber Needs Parging

A smoke chamber that requires parging will not be efficient. You might notice drafting issues or signs of creosote buildup.

But, it’s difficult for you to access the smoke chamber so you can’t be sure whether your smoke chamber needs parging or not. That is why you’ll need a professional chimney sweep for the job.

A professional chimney sweep uses special cameras to access such difficult-to-reach places. If any cracks are seen or if your smoke chamber is corbeled, the chimney sweep will recommend parging.

Most often, such issues are discovered during level 2 chimney inspections. That is why several fireplace safety organizations, including the National Fire Protection Association (NFPA) and Chimney Safety Institute of America (CSIA), recommend annual chimney inspections.

Smoke Chamber Parging Cost

The Chimney parging process costs around $900 to $2050. But the actual cost may vary based on various factors.

Smoke chamber parging costs would vary in different localities. It will also vary from season to season e.g., it’ll be higher in winters when there are a lot of bookings and lower in summers.

The final cost also depends upon the condition of your smoke chamber and how much work is needed. Moreover, the smoke chamber parging can be either spray-on parging or cast-in-place. Both of these will have different costs.

The Takeaway

Smoke chamber parging is important for the efficient working of your overall chimney. It:

• improves drafting
• reduces creosote buildup
• covers cracks
• strengthens the structure 

But it is difficult for you to inspect your smoke chamber to know whether it requires parging or not. Chimney sweeps use special cameras that can reach the most inaccessible curves and corners of the chimney. So, hire a certified chimney sweep for a complete inspection of your chimney.

A word of advice: It’s best to have your smoke chamber parging done before the winter season. It’ll be easier to book your inspection since people don’t usually get their chimney and fireplace repairs done in the summers.