Top 5 Tips to Minimize Creosote Build-Up



Creosote is no joke. 

It’s a naturally occurring byproduct of burning wood and it lingers in your chimney until you remove it. 

As the moisture from the wood mixes with the smoke that burns, it creates a tar-like substance that sticks to the inside of your flue. That’s Creosote.

Since creosote is highly flammable, it is a leading cause of house fires

Luckily there are things that you can do to minimize that risk. And that’s what we’ll talk about in today’s post. 

What is Creosote?

As I mentioned before, creosote is a naturally occurring, but dangerous, byproduct that comes from burning wood. 

When you use your fireplace, your goal should be to move the fuel (oil, natural gases, wood, pellets, etc.) through all four stages of combustion as completely as possible.

If not, you’ll get more creosote.

creosote cap

Combustion Stages

As I mentioned before, you’ll need to make sure your fire is moving the fuel through the four stages of combustion as completely as possible.

Here are the Four Stages of Combustion:

  1. Moisture evaporation
  2. Vaporization of the hydrocarbon compounds
  3. Gas vapor ignition and combustion
  4. Char burning. 

Complete combustion of wood produces water vapor, carbon dioxide, heat, and noncombustible ashes. 

The less complete the combustion is, the more carbon monoxide, combustible hydrocarbons, and other gasses are left behind. 

Unfortunately, achieving complete combustion is rare because to do so your fire must meet three conditions: 

  1. There must be sufficient heat to breakdown wood molecules into combustible hydrocarbons
  2. There must be enough oxygen mixing with the hydrocarbons
  3. There must be enough fuel

If those three conditions are not met, you get more creosote. 

Creosote originates as condensed wood smoke, tar, condensed vapors, and other compounds. It is dark brown or black and sticks inside your flue. 

Once inside the chimney, creosote builds on itself and doesn’t just go away on its own. 

It’s a very dangerous, naturally occurring, by-product that you can’t prevent.

How to Recognize Creosote

Creosote deposits appear in many different ways, depending on the moisture content. It’s not uncommon to find more than one type of creosote in a chimney. 


Here are the four main types: 


  • Sooty, ash-like deposits – found in flues because of their unlimited access to combustion air. These may be less combustible but should still be removed and taken seriously to prevent blockages, moisture retention, and chimney deterioration. 
  • Dry, flaky, black tar deposits – these are the result of deposits that have been heated and pyrolyzed. This type is easy to catch fire, even though much of the flame-producing gases have been driven off. 
  • Dense, hard, shiny black deposits – this is a tar glaze that has stuck to the chimney walls and driven off the moisture. Because the moisture is gone, but the flame-producing hydrocarbons are still present, these deposits retain a high energy content. Ignition of this type of creosote deposit burns at extremely high temperatures. 
  • Sticky, tacky, or runny deposits – this form of creosote has a consistency similar to chewing gum. Creosote in this form can be liquid in nature when the tar fog condenses with a high concentration of water vapor. 


Why Get Rid of Creosote

Creosote is the leading contributing factor to chimney fires. 

Chimney fires are responsible for an average of 22,300 house fires, 20 deaths, and $125 million in property damage every year in the United States! 

But beyond that, creosote can actually have a considerable effect on your health.

Health Issues

Exposure to creosote can have a wide range of effects on your health. 

Of course, several factors contribute to health effects, such as the level (amount) to which you are exposed, the length of time, and the number of times you’re exposed. 

And some people (like children, the elderly, and pregnant women) may be more sensitive to creosote. 

While some symptoms of exposure are mild and irritating, some symptoms can be more severe. Here are some of the most common symptoms associated with exposure to creosote:


Skin and Eye Irritation 

Exposure to even a small amount of creosote, whether direct skin contact or through vapors, can cause blistering, peeling, or reddening of the skin. 

It can also cause damage to your eyes and increase your eyes’ sensitivity to the light.

Respiratory Issues 

Long exposure to creosote vapors can irritate your lungs. 


The Environmental Protection Agency (EPA) determined that creosote is a probable human carcinogen. They found that even low levels of creosote had led to skin cancer. 

Birth Defects 

While the studies have been done on animals and not on humans, researchers have found that creosote exposure can cause birth defects, such as cleft palate, among babies born to mothers exposed to creosote during pregnancy.

House Fire

The health risks are serious. 

But the most concerning issue of creosote is chimney fires. 

Creosote is flammable and when the deposits catch on fire it creates a scorching hot fire. The leading cause of chimney fires is due to the build-up of creosote deposits inside the flue. 

The masonry and flue lining are only designed to handle certain levels of heat. 

And creosote-caused chimney fires typically far exceed that level. In fact, during chimney fires, temperatures can often exceed 2,000℉. 

The first chimney fire may not show any visible damage, but it will limit your home’s ability to handle another one.

1 – Only Burn Seasoned Wood

Seasoned wood is dry wood. 

Fresh cut wood is packed with moisture that makes it difficult to burn. This produces a dense, black smoke filled with combustion by-products. 

Your wood should have somewhere between 15-25% moisture content.


2 – Don’t Burn Artificial Logs

Artificial logs produce more combustion byproducts than regular wood. This will significantly increase the creosote build-up. 

3 – Build Hot, Clean Burning Fires

Stacking your firewood with enough space in between the logs to allow for oxygen to circulate will produce a much hotter, cleaner-burning fire. 

If you build fires like this, then you’ll have less creosote built up in your chimney. 

Watch this video on how to build a fire: 

4 – Make Sure your fire gets enough Oxygen

Open your damper before you light your fire. This will ensure that it will get enough oxygen. 

Also, make sure you build your fire properly for the sake of oxygen. 

Finally, if you have glass doors, it may be a good idea to leave them cracked open slightly so that air can circulate. 

5 – Reduce condensation by warming up your cold flue

If your chimney isn’t insulated well, your flue can get pretty cold. 

Lighting a fire when your flue is cold will create more condensation and larger creosote deposits. 

You can easily warm up your chimney by rolling newspaper to make a torch, lighting it and holding it up in the chimney. 

When the smoke from the torch is rising straight up, you’ll know that the flue is warm enough and you can build a fire!

Tips to Minimize Creosote

Now that all that information about creosote is out of the way, we can talk about things you can do to minimize the creosote build-up. 

And the good news is that you can do things to minimize the creosote. 

Here are our top 5 tips to minimize creosote build-up in your chimney:

Schedule An Inspection

The best thing you can do to manage the creosote in your home is to have your chimney looked at by a professional every year.

At Patriot Chimney, we look inside and out, fill out a detailed condition report, and talk to you (in plain language) about the condition of your chimney.

Fill out the form below to get started.

  • Hidden
  • This field is for validation purposes and should be left unchanged.

Pin It on Pinterest