What is a Glazed Creosote Build up In a Chimney?
8045 Snouffer School Rd. Gaithersburg MD 20879

What is Glazed Creosote?

glazed creosoteSoot isn’t all that builds up in the chimney from your woodburning fireplace. Creosote is a chemical compound that’s created when condensation interacts with smoke. It also builds up in the chimney. It can become a major hazard if it hardens into glazed creosote.

What is Glazed Creosote?

When wood burns, the smoke produced contains many different gases and particles like carbon monoxide and ash. As they move up through the chimney, condensation interacts with these byproducts producing creosote which builds up along the chimney walls. In the early stage of creosote build-up, it is flaky and easy to remove like soot. If it isn’t removed, it can progress to the second stage when it becomes sticky and tar-like. The third and final stage of creosote buildup is glazed creosote. It reaches this stage when there is enough creosote built up in the chimney to reduce airflow through the flue.

Creosote is flammable during all three stages, but glazed creosote is the most dangerous. If a stray spark ignites glazed creosote deposits, the fire can burn at high temperatures for a long time. This can cause serious structural damage to your chimney or spread to your home.

How to Remove Glazed Creosote

Glazed creosote is tough to remove. We have seen amateurs try to get rid of it with chains, chisels, and other heavy-duty tools that damage the chimney liner in the process. Using a fireplace with a damaged chimney liner can be as dangerous as a chimney lined with glazed creosote. Professionals get rid of glazed creosote by using industrial-grade creosote remover that will not damage the chimney liner. They spray or brush the remover onto the glazed creosote. Once it is absorbed, the creosote will begin to soften and flake until all of it can be brushed off and vacuumed out.

How to Prevent Glazed Creosote

Even though glazed creosote can be removed by a professional, stopping creosote from getting to that stage is the best way to prevent a chimney fire. There are two steps you can take to avoid third stage creosote:

Step 1: Only burn seasoned firewood.Chimney sweep in Middletown MD

Burning paper, cardboard, trash, or other flammable materials besides wood will accelerate creosote buildup because they produce more chemical byproducts as they burn. Green or unseasoned firewood also produces more chemical byproducts when burned. If you only burn seasoned firewood, less creosote will build up in the chimney during burning season.

Step 2: Schedule annual chimney cleanings.

Scheduling a chimney cleaning every spring, after using the fireplace in the winter, will prevent creosote from building up year after year. If you schedule a cleaning once a year, it is unlikely the creosote in your chimney will reach the third stage. It will also open up the airway in your chimney so that your fireplace functions properly next winter.


Need to schedule a chimney cleaning this year? Give High’s Chimney Service a call! Our team of CSIA- and CCP-certified chimney technicians serve residents throughout Virginia, Maryland, and Washington, DC. Call 703-550-5115 or 301-519-3500