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The C’s of Chimney and Fireplace Terminology

If you become familiar with essential chimney and fireplace terminology, it can be easier to understand chimney-related strategies for keeping your home and family safe. Maintenance of chimney systems and fireplaces is frequently neglected, and dangerous house fires are among the devastating results. The following are important and commonly used“C” terms related to fireplaces and chimneys.

smokey fireplace, carytown vaCarbon Monoxide

Carbon monoxide (CO) is produced by incomplete combustion of wood, natural gas, and coal and is a result of insufficient oxygen. When these toxic fumes enter the home instead of being vented to the out-of-doors, they are life-threatening. Carbon monoxide is known as the Silent Killer because it is odorless, tasteless, colorless, and symptomless. Detection requires a carbon monoxide detector. If the chimney flue is damaged or if the fireplace smokes, occupants of the home are in danger of potentially deadly carbon monoxide exposure.

(Smoke) Chamber

In masonry fireplaces, combustion gases move from the firebox, through the damper, and into the smoke chamber before moving up through the chimney flue, which is a narrower passageway. The purpose of the smoke chamber is to gently compress the fumes while preventing a backdraft. The tapered walls in the smoke chamber help to promote a strong updraft through and out the chimney.


A wood-constructed chimney is known as a “chase.” The exterior is decorative, and the chase conceals the insulated metal flue inside the chimney. Materials decorative chases are constructed with include wood siding, aluminum, simulated stone, and vinyl.

Chase Cover

Chase covers are essential accessories placed at the top of chimney chases. The purpose of chase covers is to prevent rain, snow, sleet, and hail from entering the chimney. Galvanized chase covers are not recommended because they are prone to rust and leak. Stainless steel and copper chase covers provide lasting protection against leaks because they don’t rust.

Chimney Cap

Chimney caps are installed on masonry chimneys to keep moisture out. A flue cap keeps out the rain, etc., but a full-mount chimney cap will also protect the chimney crown, which is vulnerable to crack and leak because of continuous exposure to harsh outdoor elements. Chimney caps with mesh are recommended because they also keep out debris and animals.

Chimney Cleaning

Dirty chimneys cause house fires in the U.S. every year, many of which result in fatalities. Annual chimney cleaning is recommended by the National Fire Protection Association (NFPA), but the Chimney Safety Institute of America (CSIA) suggests chimney cleaning once creosote buildup measures 1/8” thick.

Chimney Cleaning Log

Chimney cleaning logs aka creosote sweepings logs are used by many homeowners to reduce the presence of flammable creosote in the chimney. Contrary to a widespread chimney myth, chimney cleaning logs do not serve as a substitute for chimney sweep services. Chimney cleaning services are essential even if you burn chimney cleaning logs.

Chimney Inspection

Annual chimney inspections are strongly recommended by all leading fire safety organizations in the U.S. Whether or not a chimney is being used, it should be inspected each year. Threats caused by moisture are among the reasons inspections are so important. Also, a special camera used during a Level II chimney inspection is sometimes the only way to check the chimney flue liner, which exposes a home’s occupants to dangerous health conditions if it has even a small crack.

Chimney Liner aka Flue

A chimney flue is a liner inside the chimney that contains heat, protecting combustible parts of the home, and prevents toxic gases from entering the home. For a chimney liner to be effective, it must be free of any deterioration or damage, no matter how small.


As the smoke from wood fires is traveling through the chimney liner, it cools and leaves deposits in the liner. The deposits are tar-like and highly flammable. If a chimney liner is not cleaned regularly, creosote builds up in layers until it can ultimately obstruct the chimney. Creosote heightens the threat of a dangerous chimney fire.

chimney crown repair in midlothian va


A chimney crown is the white, concrete part at the very top of a chimney. The purpose of this chimney component is to prevent moisture from getting between the chimney exterior and the flue liner. The material chimney crowns are made with is prone to crack, resulting in chimney leaks.

Schedule your annual chimney inspection, chimney cleaning, chimney maintenance, masonry rebuilding, chimney restoration, and all chimney services with us. We are proud to say that all of our chimney sweeps are CSIA-certified.

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