As you relax in front of your fireplace or bask in the warmth of your wood stove, the last thing you are likely to be thinking about is the condition of your chimney. However, if you don’t give some thought to it before you light those winter fires, your enjoyment may be very short-lived.
Dirty chimneys can cause chimney fires, which damage structures, destroy homes, and injure or kill people. Chimney fires can burn explosively – noisy and dramatic enough to be detected by neighbors or people passing by. Flames or dense smoke may shoot from the top of the chimney.
The Majority of Chimney Fires Go Undetected
Slow-burning chimney fires don’t get enough air or have fuel to be dramatic or visible and they often go undetected until a later chimney inspection, but, the temperatures they reach are very high and can cause much damage to the chimney structure and nearby combustible parts of the house.
The Roselle Fire Department was dispatched to a chimney fire call in November 2019. This particular fire probably burned in the chimney chase of the home for two hours before making its way to the attic, where it continued to grow for another hour before being noticed. The fireplace had a gas log unit that was shut off at 10:00 p.m., and the fire was not noticed until after 3:00 a.m., at which time the residents called 9-1-1. This time line provides an example of how long a fire can smolder and grow rather large before being noticed.
Creosote Can Cause Chimney Fires
Creosote is a black or brown residue that results from the condensation that forms after smoke, water vapor, gases, unburned wood particles, hydrocarbon, and tar fog flow up into the relatively cooler chimney. Creosote can be crusty and flaky; tar-like, drippy and sticky; or shiny and hardened. All forms are highly combustible. If it builds up in sufficient quantities – and the internal flue temperature is high enough – the result could be a chimney fire.
Nine Signs that You’ve Had a Chimney Fire
Since a chimney that has been damaged by a chimney fire can endanger a home and its occupants, it’s important to have your chimney regularly inspected by a chimney sweep. Here are the signs that a professional chimney sweep looks for:
- “Puffy” or “honey combed” creosote;
- Warped metal of the damper, metal smoke chamber, connector pipe or factory-built metal chimney;
- Cracked or collapsed flue tiles, or tiles with large chunks missing;
- Discolored and/or distorted rain cap;
- Heat-damaged TV antenna attached to the chimney;
- Creosote flakes and pieces found on the roof or ground;
- Roofing material damaged from hot creosote;
- Cracks in exterior masonry; and
- Evidence of smoke escaping through mortar joints of masonry or tile liners.
Clean chimneys don’t catch fire. The Roselle Fire Department recommends having your chimney inspected annually, with sweeps and repairs to it whenever needed. Your chimney sweep may have other maintenance recommendations depending on how you use your fireplace or stove.