Does My Chimney Need a Liner?

A liner may seem like another part of a chimney, whose function you don’t quite understand. But, it actually plays a very important role. 

Designed using metal, ceramic, or clay tile, a liner serves to prevent heat transfer to surrounding support structures and protect your masonry.

Here is everything you need to know about chimney liners.

Do you need a chimney liner for an oil furnace?

Yes, you do need a chimney liner for two reasons. One, a new liner prevents the masonry materials inside your chimney from being damaged and two, it prevents an accidental fire

When you think of brick, one of the things that come to mind is its strong build. But what you don’t know is that this building material is also quite porous, particularly if you consider the mortar that keeps the bricks intact. 

Now, once you light up your oil furnace, the burning of fuel generates a toxic by-product called soot. This is simply a mixture of unburnt carbon and sulfur. 

If your chimney does not have a steel liner or any other liner, the soot starts eroding the chimney masonry materials. The erosion creates cracks that allow harmful carbon monoxide and other noxious substances to find their way into your house. 

With a chimney liner, it acts as a barrier preventing the harmful by-products from ever penetrating into your home. 

Another reason why you should invest in a chimney liner is to avoid house fires. And before you ask, yes, chimneys are typically made of materials that don’t catch fire. 

However, the air inside a chimney gets quite hot. If your chimney is resting against support structures that are combustible, then the heat can ignite a fire on these materials. 

With a liner though, the chimney walls don’t conduct heat to nearby structures; hence, guaranteeing maximum safety. This is because the liners are made of materials that can contain this heat rather than conduct it. 

Do I need an insulated chimney liner?

Yes, it’s best to invest in your chimney liner’s insulation if you’re planning to install one

The greatest benefit of insulating your liner is that it effectively prevents the accumulation of creosote inside the chimney. 

A report released by the National Fire Protection Association reveals that creosote is one of the primary causes of house fires; hence the need to prevent it from accumulating. 

So how exactly is this substance formed? Well, if the temperature of the smoke inside the chimney falls below 250°F, the combustion gases begin to condense and solidify, creating a tar-like substance. This substance is what is referred to as creosote. 

Insulating the liner ensures that these gases remain hot as they travel all the way up and get released into the atmosphere. This, in turn, minimizes the likelihood of condensation, which translates to less creosote buildup. 

Important to note is that creosote is more common among wood-burning stoves than it is with gas or oil furnaces. If a fire ignites in a wood-burning stove, it may burn for a pretty long time.

How much does it cost to have a chimney liner installed?

If you’ve decided to install a liner on your chimney, the first thing you’ll want to know is how much you’ll spend on this affair.

Generally, you can expect to pay between $2,500 and $5,000 for the entire installation. 

The installation costs vary widely depending on factors, such as:

  • Type of chimney liner
  • Inspection and cleaning
  • Permits and labor costs

But consider all the benefits you’ll be getting, especially when it comes to improving your home’s safety. We understand that this is a lot of money to pay for something that won’t be adding any visual appeal to your home.

Types of liner

There are five main types of chimney liners. This is how much you can expect to pay for each:

TypeAmount to be paid per foot
Stainless steel liner$65
Aluminum liner$12
Terra-cotta/ clay tiles$10
Cast-in-place liner$250
Thermocrete liner$200
Inspection and cleaning

If you want your new liner to be properly installed, then start by getting it cleaned.  This way, the liner will be installed on a clean slate. A professional chimney cleaning service costs between $125 and $250. 


In the majority of states, you may be required to get a permit before undertaking such a project. This will also cost you money, approximately $50 to $200.


Installing a chimney liner calls for a great deal of knowledge and expertise, which is why we always recommend that you hire a professional. 

Unfortunately, the cost of labor may be quite steep, averaging $400 to $1,250. Most technicians ask to be paid by the hour so this will boil down to the complexity of the job at hand. 

What size chimney liner do I need?

One of the most important factors to consider when buying a chimney liner is size. Getting a correctly sized liner is important to ensure it works efficiently. 

That said, there are specific metrics you’ll need to figure out first namely: the length, diameter, and area of the liner. 

Determining the length

The length of the liner should match that of the chimney. So to estimate this, drop a tape measure through the chimney. This will allow you to measure the distance from the chimney’s top, all the way up to the opening below. To be safe, consider adding an additional foot or two for the liner.

Determining the diameter

The rule of thumb here is to go by the size of the outlet on your wood-burning stove or appliance. 

For instance, a standard wood stove requires the liner to be between 6 and 8 inches in diameter. Overall, a minimum diameter of 6 inches is suitable for most chimney inserts. 

Open fireplaces

For a fireplace, there are two key things to consider. One is the area of the fireplace opening and two, the diameter of the liner. To find the area of the fireplace section, multiply its length by width. 

Now, if your chimney is less than 25 feet high, the area of the lining should be 1/10th the area of the opening. For chimneys that go up to more than 25 feet high, the lining’s area should be 1/12th the area of the opening. 

When it comes to diameter, use the following chart to guide you:

Fireplace opening Diameter of the liner
At least 600 sq. in9 inches
601 to 760 sq. in10 inches
761 to 942 sq. in11 inches
943 to 1140 sq. in12 inches
1141 to 1356 sq. in14 inches
1357 to 1846 sq.in16 inches

How long will my chimney liner last?

This primarily depends on the type of liner you’ll install. Chimney walls outfitted with ceramic and clay liners are the most durable, offering a lifespan of up to 50 years.

The stainless steel liner doesn’t last that long so you’ll probably need a new one every 20 years or so. 

It’s crucial to point out that just because your lining is expected to last a given number of years doesn’t mean that it will. Its durability may be affected by natural wear and tear, constant exposure to harsh weather elements, and other forces of Mother Nature. 

As such, you should have your existing chimney inspected regularly to ensure it’s still in pristine condition. If it’s not, start planning for a suitable replacement. 


If you have a wood-burning, gas, or oil furnace, there’s a good chance that you also have a chimney. This is what lets out the toxic exhaust gases produced from the heating system that warms up your home. If you have a chimney, it’s crucial that you get it lined with either a metal or clay liner. 

This lining prevents the masonry materials that make up your chimney from getting wrecked. It also helps to contain the heat from the gaseous air that passes through the chimney.

This, in turn, prevents combustible support structures that are nearby from catching fire.

NOTE FROM the author

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- Tiffany B.