The Hidden Danger of Creosote Buildup During the Burning Season

Fireplaces aren’t the most efficient home heating systems, but we challenge you to find one that’s more beautiful. There’s something about the real flame, crackling sounds, and earthy aromas that speak to our souls, something a gas fireplace or furnace simply doesn’t do. However, tucked behind that cozy hearth is a stealthy, flammable villain: creosote. It’s the tar-like residue that forms inside the chimney when you burn wood. Left unchecked, creosote can ignite and cause a chimney fire, resulting in thousands of dollars in damage or the loss of your home.

Let’s get into the dirty world of creosote, why it’s dangerous, and what you can do to protect yourself.

Why Creosote Builds Up

When you burn wet or unseasoned wood, or when your fire smolders at low temperatures, smoke carries unburned hydrocarbons up the flue. As the smoke cools along the cooler chimney walls, those hydrocarbons condense and harden into creosote. Over time, this layer thickens, and the more glazed or “tarry” the creosote, the more likely it is to ignite. Even a thin film (fractions of an inch) can be an ignition hazard.

How Big is the Risk?

You’d be surprised by how many fireplace owners downplay the danger of creosote, but the statistics don’t lie.

• A U.S. Fire Administration (USFA) analysis of heating fires (2017-2019) estimated that roughly 34,200 residential heating fires occurred during that period, and, more importantly, that about 77% of those fires were confined to chimneys, flues, or fuel burners.
• Industry and public-safety groups report approximately 25,000 chimney fires annually in the United States, causing roughly $125 million in property damage.
• The EPA and other safety publications say that most fireplace and chimney fires are caused by creosote buildup and list dirty chimneys as a leading factor in heating-related residential fires.

What Happens When Creosote Ignites

Creosote fires can burn at extremely high temperatures, sometimes over 2,000˚F, which is hot enough to crack masonry or collapse flue liners, allowing the flames to reach the home’s combustible frame. Even when a chimney fire seems “contained”, structural damage can make the subsequent fire much worse. And here’s the rub: many chimney fires go unnoticed the first time around; it’s the second or third where the real damage occurs.

What Can You Do?

Scared yet? Well, the good news is that this doesn’t have to happen. Here’s what you can do to minimize creosote buildup and the risk of a chimney fire, and it’s pretty simple.

• Have an annual chimney cleaning and inspection by a certified chimney sweep. Professional cleanings are more thorough than using creosote-removing logs, and the technician can check for other issues, such as blockages or damage that could compromise venting.
• Burn seasoned, dry wood (moisture content under 20%). It burns hotter and leaves finer, less tacky residue.
• Watch for the warning signs: strong, smoky odors, smoke entering the room, loud, roaring noises from the chimney, or dark, tarry deposits visible at the top of the flue.
• Install and test smoke and carbon monoxide alarms because chimney fires can spread or lead to dangerous gas exposure even if the chimney itself contains the flames.

Creosote is a hidden winter risk because it accumulates quietly over time. It can quickly turn a pleasant evening or holiday gathering into a disaster in minutes. However, as mentioned, this hazard is preventable mainly by burning the right kind of wood, getting regular cleanings and inspections by a certified pro, and ensuring your smoke and CO detectors are working correctly.

Call Advance Today!

Advance Chimney Sweeps is the most trusted chimney and fireplace professional in Pittsburgh, PA. If you can’t remember the last time you had your chimney cleaned or inspected, now’s the time to call us. We’re licensed and insured, and use state-of-the-art equipment to ensure the job is done right the first time.