Smoke, water vapor, tar fog, and other by-products of combustion travel up the flue and cool slightly creating condensation. Creosote is the black or brown by-product that sticks to the inside of the chimney’s flue as a result of this action. The speed at which creosote builds up depends on several factors including your burning habits, and the types of wood you burn.
Creosote is a highly combustible substance and must be removed to prevent chimney fires. I’ve discussed the methods of locating a reliable, certified chimney sweep in previous blog posts. A yearly cleaning and inspection is highly recommended to prevent chimney fires and house fires.
A very simple chimney inspection that you may do on your own is a visual inspection. Use a bright flashlight, and look at the inside of your flue. You may look up from the fireplace itself or down from the opening at the top of your chimney. You can easily see creosote buildup if it is present. It may look shiny, or like tar on the inside of your flue, or it may look crusty or flaky.
You may notice abnormalities in the appearance of the creosote. Some types of abnormalities may be a sign of a previous chimney fire. Here are a few things to keep in mind:
Signs of a Chimney Fire
- Creosote looks puffy or has a honeycomb appearance
- Creosote flakes in the stove, fireplace, or roof
- Any warped metal such as the damper or connector pipes
- Damaged flue tiles
- Damaged or discolored masonry
- Damaged roofing material
- A damaged or discolored chimney cap
Damages caused by a chimney fire vary due to the amount of creosote buildup and your burning habits. You may only need to replace a few minor things and hire a chimney sweep to make sure it doesn’t happen again. No one wants to consider the worst-case scenario. Yearly maintenance is the key to fireplace and chimney safety.
Quick note: If you’re planning to buy a home with an existing fireplace or stove and chimney, request an inspection of the flue and chimney before you make an offer. Perform an initial inspection on your own by using the guidelines listed above if you wish. Don’t take a chance on buying a home without a full inspection by a certified chimney sweep.