Several chimney flues rising out of a few chimneys along the skyline

Chimney Flue

Originally contributed by • last updated 3/1/2021


Whether you live in a home with an older masonry chimney or you’ve recently had a newer one installed as part of a new build, proper maintenance and upkeep are vital for a long life and safe operation. On the outside, chimneys are often admired for being well-designed, formidable structures. But don’t let their appearance fool you because, as the old saying goes, “it’s what’s on the inside that counts.” And the inside of a chimney is called the flue.


If the chimney is the visible masonry structure rising out of the firebox through the roof to the exterior of the home, the chimney flue is the open-air space inside the chimney that vents hot air, smoke, and gases from the fire to the outside. As the hot air rises through the flue to the exterior of the home, it draws cooler air from the interior of the building through the firebox back into the flue. Airflow plays an important role in controlling the temperature of the fire and overall heat retention, and is typically regulated by dampers, which open and close to allow more or less air to move through the flue.

What Is A Chimney Flue Liner And Is It Necessary?

Having a beautiful warm hearth to come home to on a cold winter’s eve is a luxury many homeowners dream of. Despite being strong masonry structures, chimneys are not damage proof. That’s why, to help protect your chimney, it’s highly recommended (and mandated in some areas) that you install a chimney flue liner:

  • Chimney flue liners (commonly referred to as chimney liners) are protective coverings that line the inside of the flue to create a conduit that carries away hot air, gases, and smoke. They also help with efficiency by creating the proper vent size and airflow.
  • Chimney flues not only help with efficiency, they also decrease the amount of wear and tear on the masonry work. Even though chimneys are formidable structures, they can still incur damage from continuous use.
  • Although not all areas have the same regulations, chimney liners are required by law in many places. Be sure to check requirements for your location.