Does Your Dirty Chimney Really Need to Be Swept?

Dirty Chimney Sweep Hands | Doctor Flue“Was it dirty?”

Our technicians are often asked this question when evaluating a homeowner’s wood burning system. In reality, anyone can reach into a chimney and get soot on their hand. Every chimney is a little dirty! But, that doesn't necessarily mean that it needs to be swept.

So how do we determine if a dirty chimney should actually be swept? We look to a third-party for guidelines, and what better authority than the Chimney Safety Institute of America (CSIA)? In the manual for the CSIA, it states that accumulations of third-degree glazed creosote more than 1/8 of an inch shall be removed.

It is with these guidelines that we assess whether or not chimney is dirty. These guidelines were based on many years of experience of determining approximately how much creosote buildup in the chimney is dangerous.

Basic Combustion Triangle

When creosote builds up in a chimney, it dramatically increases the risk of a chimney fire. The volatility of creosote in a flue is directly proportional to the amount of oxygen and moisture content present in the chimney system. Then, of course we would need heat in the chimney to start the fire. The creosote is the third element, the fuel. There are three things needed for combustion: fuel, heat, and oxygen. These three elements make up the basic combustion triangle. In a dirty chimney, the fuel is the creosote. The introduction of heat, obviously is the fire. And oxygen introduced into the system where there is enough fuel and ample heat will start combustion.

Combustion inside the flue of a chimney is considered to be a chimney fire, by definition. A chimney fire is considered to be an “unfriendly fire”, especially in the insurance language of your policy. “Friendly fire” would be the fire that is actually in the fireplace. There's not supposed to be fire in the flue portion of the chimney.

Home Insurance and your Chimney

Insurance policies do usually cover damage to chimneys if there's been a chimney fire. We often state the language on a claim as a "sudden occurrence of unfriendly fire." If a chimney is lined with clay tile, typical damage would include the vertical crack and separation of the existing tile in the flue. To correct the problem, a homeowner would need to have the chimney liner replaced.

Contact Doctor Flue

So, was a dirty? There's much more to the question to take into consideration before answering the question. Depend on the certified technicians here at Doctor Flue to make the decision for you. If you wait too long to get your dirty chimney cleaned, you could face potentially dangerous consequences.

Contact Doctor Flue to schedule your chimney cleaning. Give us a call at 800-438-3583 or send us an email at to request an appointment today!

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