Anatomy of a Chimney

When most people think of chimneys, they think of fireplaces. For thousands of years, we have gathered around an open fire for a sense of warmth, safety, family and friends, and the fireplace is still a focus of gathering in homes.

Along with the many pleasures of having a fireplace in the home, there are some practical considerations. When you’re dealing with an element as dangerous as fire, knowledge is power. Beyond the fireplace there is the chimney and most home owners are only vaguely familiar with the contents that spread beyond the hearth and the chimney. The truth is that the fireplace and chimney can consist of up to 22 parts.

Knowing about these parts and their functions can be useful in general maintenance, troubleshooting, or even when trying to talk to a fireplace and chimney expert about your service. Use the following guide to understand the various parts of your chimney and be prepared for your annual chimney inspection!

Anatomy of a Chimney

Chimney Crown – Your chimney crown protects the chimney from water damage entering through small cracks. Without a proper chimney crown- or if you have a cracked one, rain water seeps into the bricks and mortar of your chimney structure and causes damage.

Flue – A flue is a passage for transferring exhaust gases from the fireplace to the outdoors. A flue may be a duct, pipe, vent, or chimney. An unlined chimney is technically a flue, although an unlined chimney is a fire hazard.

Flue Lining – A lining must be used to ensure minimal accumulation of flammable debris. and must be free and clear of any defects in order to serve it’s purpose.

Chimney Cap – A chimney cap will prevent animals from entering your home, keep the moisture out, and protect the roof from embers that can potentially start a house fire.

Flashing – The chimney flashing is the transition piece, made of likely lead, rubber or copper, that meets the roof with the brick structure. When the chimney is leaking, the flashing is one of the first areas assessed to check for breaks and/or voids.

Anatomy of a Fireplace

Smoke Chamber – The purpose of the smoke chamber is to gently compress the byproducts of combustion into a smaller space (the chimney) without causing back draft.

Chimney Damper – A Chimney Damper is a lever or pulley activated door within your chimney. It must remain open while the fireplace is in use and can be closed to prevent energy loss when your fireplace isn’t being used.

Smoke Shelf – This shelf is just behind the chimney damper. Because the shelf is flat it catches falling debris and rain water and helps move large volumes of smoke into the small chimney.

Throat – This is the space just below the damper and just above the firebox, where the fire first passes through.

Lintel – A reinforcement steel bar that is used during construction to hold up the top row of brick of the firebox opening. Voids between the steel and masonry are common causes of smoke problems.

Firebox – The firebox is the section of the chimney system in which a person builds a fire. A proper firebox is lined with firebrick, a substance of refractory ceramic, which can become cracked or weakened after years of use. This area of the chimney is often in need of repair. It is recommended to have a thorough inspection of the firebox after a seasons usage.

Hearth – This is the space on which the fire burns, also known as a firebox floor. As with the firebrick, it must be able to handle both the potential corrosiveness of the burned material and the high heats it can be subjected to.

Hearth Extension – This is the space that occupies the floor just outside of the firebox. It’s made of heat resistant material such as tile or brick to reduce the chance of fires.

Foundation – The lowest part of the chimney walls, this is made of heavy duty brick or cinder block. It is the structural support for the rest of the chimney and is exposed to potentially hot ash.

Fireplace Face – This is the area between the mantel and the fireplace itself. It is usually brick or other non-combustible material, as it must be adequate enough to handle the heat of the fireplace below it.

We hope you now have a better understanding of the importance of chimney maintenance. Call us today, and we can send a professionally licensed and experienced chimney technician to determine your chimney needs!

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