One of the most overlooked fire hazards in homes with fireplaces or wood-burning stoves builds quietly over time—often unnoticed until it becomes dangerous.

That hazard is creosote, a dark, tar-like residue that forms inside chimneys and flues when wood is burned.

As smoke rises and cools, it leaves behind particles that stick to the chimney walls. Over months or years, this buildup can become thick and highly combustible.

Creosote develops in stages. Early deposits appear as light flakes or dust and are easier to remove. As it accumulates, it hardens into a shiny crust, and eventually forms a dense, tar-like coating.

At its most advanced stage, creosote can contain extremely high levels of combustible material, making it a serious fire risk.

If ignited, it can cause a chimney fire that burns at temperatures exceeding 2,000°F, potentially damaging the chimney structure and spreading to the rest of the home.

Warning signs include dark, oily stains near the fireplace, strong smoky odors, restricted airflow, debris falling into the firebox, or unusual sounds during a fire.

Preventing buildup starts with burning properly seasoned wood, maintaining hot, efficient fires, and ensuring good airflow. The most important step, however, is scheduling regular professional chimney inspections and cleanings to reduce risk and keep your home safe.