What Is a Chimney Liner? Keeping Your Fireplace Safe With This Simple Flue Tube

There’s nothing toastier than being curled up in front of a roaring fireplace. One way to make sure the hearth stays as safe as it is warm? Install a chimney liner to help direct fumes up and out of your fireplace. Here’s what to know about chimney liners, including whether you need one and the different types.  

What Is a Chimney Liner?

A chimney liner, or a flue liner, is a flexible tube that connects to your stove pipe and runs up the length of your chimney. It helps your fireplace and chimney to work efficiently—and safely—by carrying fumes up and out of your chimney.

A liner helps keep the fireplace roaring without starting a roaring blaze elsewhere in your home. A chimney liner, which can be made from many different materials which we’ll discuss a little later, also works to protect the masonry of your chimney walls themselves from extreme heat and flame.

Chimney liners have been in use since the 1940s when inspectors pointed out how dangerously unsafe the unlined chimneys could be as they age. Now, most fire codes make chimney liners a mandatory part of caring for your working fireplace, though the official guidelines vary from state to state. Consult your local Department of Buildings or local chimney liner installer for more information.

Do I Need a Chimney Liner?

While chimney liners clearly have benefits, you may wonder if you need one. The short answer is yes. Although they’re not always required by local codes, most fireplace experts recommend chimney liners to protect your home from fire hazards. Some municipalities, like Chicago, require that you have a liner in your chimney. There is even more reason to install a liner if you notice some telltale signs.

Benefits of a Chimney Liner 

In a nutshell, chimney liners make the chimney and chimney stack safer over time. Let’s break down how exactly they do that. 

Protects House’s Woodwork 

According to the National Bureau for Standards, chimneys without liners let heat move through the chimney so fast that the woodwork near the chimney caught fire in just under 4 hours. Liners help prevent the woodwork from catching fire at all. 

Protects Chimney Masonry 

Traditional brick and mortar chimneys without liners can do the job, but they also put your health at risk. Over time, an unlined chimney can have its mortar corroded by the forces of combustion. This can cause space for gases like carbon monoxide to escape from the chimney and into the home. A chimney liner prevents this from happening. 

Keeps Wood-Burning Stoves Functional 

Wood-burning stoves and other stove-based appliances rely on the chimney to be in the best working order. With no liner, or an ill-fitted chimney liner in place, the stove may not have the proper connection it needs, which can mean carbon monoxide in your home, and a wood-burning stove that isn’t working the way it should be.

Signs You Should Get a Chimney Liner 

Here are common signs you need to replace your chimney liner:

• You notice crumbling brick and mortar inside your chimney walls.

• You see creosote buildup in your chimney (a dark, tar-like, or shiny residue).

• You notice condensation, water, or rust inside your chimney.

• You recently moved (especially if it’s an older home).

• You converted your fireplace, such as from gas to wood-burning.

• Your fires are especially smoky or smelly. 

• You notice clay pieces or flakes in the hearth.

• You recently had a chimney fire.

• Your chimney liner is over 15 years old.

Types of Chimney Liners

Clay and metal are two popular materials used to make chimney liners. There are other options too, and they all have their pros and cons.

• Clay tile: The most common option and the least expensive is made of clay tiles. The only downside is that it can’t absorb rapidly rising heat in the case of a chimney fire.

• Cast-in-place: This one has a lightweight cement liner that’s durable and long-lasting for any fuel type, but it can cost more than other options.

• Metal: This is often made of steel or aluminum. Stainless steel is suitable for all fuel types, but aluminum works only with gas. Metal liners are durable but more expensive than clay.

What Size Chimney Liner Do I Need?

The size of your chimney liner depends on the size of your fireplace opening and the height of your chimney. 

For fireplaces with chimneys under 25 feet, use a 10:1 ratio (liner area to fireplace opening). For chimneys over 25 feet, use a 12:1 ratio. The liner should not be smaller than the exhaust hole, and the area should not exceed three times the exhaust hole’s area. Measure the height from the top crown of your chimney to the top of the smoke chamber.

If you’re unsure of the size of your chimney liner, work with a local chimney pro who can ensure the proper size and install it for you.

Chimney Liner Installation Cost

For the average homeowner, having a chimney liner installed costs about $2,500. For more expensive materials, prices tend to average at $5,000 and could climb to $7,000. With an easy-to-install material like aluminum, the DIY cost of materials and equipment could be as low as $625.

DIY vs. Hiring a Pro

Chimney liners are an essential component of your fireplace’s structure and safety measures. With that in mind, we recommend working with a chimney professional to install or replace a chimney liner to ensure your personal and property safety. Plus, a chimney pro can assess your chimney, recommend the best type of liner for it, and complete the installation efficiently and safely.