Let’s be honest: of all the places in your home that you could have an out-of-control fire, the chimney seems like an “okay” spot for it. After all, aren’t hearths designed to contain fires? And aren’t they built to withstand smoke and heat?
Unfortunately, while they are usually capable of dealing with decent-sized flames in a connected fireplace, that situation is a far cry from the chimney itself being on fire. Chimney fires are destructive, costly to recover from, and potentially quite dangerous. Read on for more information about this phenomenon, including ways to prevent it from happening in your home.
Here’s a useful check list to go through every fall to prepare your home for the winter months.
Why Chimney Fires Occur
More often than not, chimney fires start when built-up creosote inside the structure ignites. Creosote is a byproduct of wood combustion; it consists mainly of tar, is tacky to the touch, and is highly flammable. Traces of the stuff can be found in smoke, and when smoke rises up from a fireplace, it mingles with cold air and water vapor.
This causes the creosote to solidify and stick to the liner (or the brickwork itself, if the chimney is unlined). Creosote is more likely to accrue in chimneys with poor ventilation, but because a buildup of creosote can cause ventilation issues, creosote essentially exists in a self-perpetuating cycle. In severe cases, all it takes is a single, errant spark to ignite all of the accumulated creosote in a chimney.
Improperly installed or maintained liners can also cause issues if they fail to contain the sparks and embers naturally produced by a hearth fire. Although the liner is designed to withstand the high temperatures of open flames and cinders, the rest of the chimney (and the surrounding areas, especially your attic) can’t handle the heat and combustion so easily. Again, a few errant sparks can be the beginning of a blazing inferno.
The Scene of the Crime
Odd as it may sound, some chimney fires go completely unnoticed. While it’s possible (and quite easy) for chimney fires to spread to a house’s roof or attic, it’s also not uncommon for them to run out of oxygen and fizzle out without ever leaving the flue. And because people generally don’t spend much time staring at their chimneys, they just don’t realize that anything is amiss. It’s not until later, when they’re having it inspected for whatever reason, that a technician informs them that they dodged a bullet.
Here are some signs of fire damage in chimneys:
- Caked-on creosote having a “puffy” or honeycomb-like appearance.
- Warping of metal internal mechanisms.
- Flue tiles that are damaged, loose, or missing large chunks.
- Visible damage to (or warping of) the chimney cap.
- Scorch marks on the flashing or roof.
- Cracks or smoke damage to the chimney’s mortar or brickwork.
- Chunks or flakes of creosote outside the chimney itself.
Now, these are subtle signs that are detectable after the fact. Signs that a chimney is currently on fire include:
- Cracking, popping, or rumbling noises coming from within the structure.
- Thick, black smoke pouring from the top of the chimney. While some smoke is normal when a fuel source is burned in the fireplace, smoke will be noticeably darker and denser.
- Visible flames shooting out of the top of the chimney.
- A “burnt” smell or intense heat radiating from the chimney, especially if the fireplace is not currently in use.
If you happen to notice that your chimney is currently burning, you should immediately evacuate your home and call 911! Don’t make the mistake of assuming that the fire will put itself out; house fires are not the kind of thing that people should gamble on!
One way to help keep the fire at bay until emergency services arrive is to take a garden hose and soak your chimney’s flashing and the surrounding area with water; this will reduce the likelihood that the fire will spread to your roof. However, please only attempt this technique if you can do so without putting yourself (or others) in harm’s way!
Beat the Heat
The number one way to prevent chimney fires is to have it professionally inspected and cleaned annually. A licensed technician will be able to examine every inch of your chimney and fireplace to verify that everything is working properly. If something is amiss, it’s best to catch and solve the problem before it escalates.
Chimney caps can also be critical for fire prevention. A humble cap can do wonders for keeping debris (e.g., sticks, leaves, airborne pieces of garbage) and animals from getting inside and causing blockages. Not only will blockages contribute to creosote buildup, but the detritus itself may essentially become kindling for any fire that erupts.
Chimney fires can be destructive (and a more than a little frightening), but the good news is that they’re fairly easy to prevent. As with all other structural issues in your home, it’s absolutely critical that you pay attention and perform regular maintenance. If you suspect that something is wrong, it’s never a good idea to simply ignore the situation in hopes that it will resolve itself. So tackle problems as soon as you notice them…or hand the job over to a professional. Cleaning and repairing a chimney is a dirty job, but someone’s gotta do it!
