An Insider’s Guide to Soot Buildup

There are over 20,000 chimney and fireplace-related fires each year in the United States. A majority of these fires are caused by a buildup of creosote, more commonly known as soot. Here are some facts we think you should know about soot in your chimney.

What Is Soot?

Soot occurs naturally by burning fuel, such as wood, in your fireplace. Soot cannot be prevented, and is the result of unburned fuel collecting and forming as a black powder, flakes, or a glaze on your chimney liner. Because it is unburned fuel, soot is highly flammable.

Soot Hazards

A buildup of soot can cause a fire when the temperature inside of the chimney rises. As the temperature rises, the soot can ignite, causing a fire that can potentially reach other areas of the home, such as the roof. A buildup of soot will also prevent smoke and gases like carbon dioxide from leaving your home through the chimney. Instead, the smoke and gases can enter into your home, potentially causing an unhealthy environment and stains on walls, ceilings, or furniture. Soot can also create a foul, musty odor, which can worsen in summer heat and humidity.

Contributors to Soot Buildup

While creosote buildup in your chimney cannot be totally prevented, there are ways to reduce soot buildup in your chimney. Some of the factors that can increase soot buildup include the following:

  • Burning artificial logs
  • Slow, smoldering fires
  • A buildup of creosote in your chimney
  • Burning trash

Oftentimes, the creosote that occurs from these situations is highly flammable.

Removing Soot

To help prevent the hazards of a soot buildup, including the potential for fire, you should have your chimney cleaned. But when should you remove soot buildup? The answer can depend on how often the chimney is used, the type of fireplace you have, what has been burned in the fireplace, and the condition of the chimney.

The National Fire Protection Association recommends that your chimney be inspected for damage and buildup (both of soot and any other blockage, such as animal nests) at least once a year. The Chimney Safety Institute of America recommends that an open masonry chimney be swept when there is a 1/8″ buildup of soot. For factory-built fireplaces, they recommend sweeping if there is enough buildup to cause a chimney fire capable of damaging the chimney or home. When you get expert soot removal for your chimney, the professional will also inspect it for any damages or potential issues.