What is Creosote?

Creosote is a dangerous byproduct of burning firewood and will stay in your chimney until it’s removed. In many cases creosote production can be kept at a minimum by burning low moisture wood but can be found in much higher quantities when the wood isn't properly combusted.

It can have both short-term and long-term effects on your fireplace and chimney if it is left to build up. 

“Creosote is a black tar-like byproduct of burning wood that can line the inside of flues or chimneys and cause longer-term issues until its removed. Creosote can be produced in higher quantities when there's a problem with the wood or the airflow to the fire.”

Why should you care about Creosote?

1. It is expensive to clean up. Creosote buildup can prevent air and smoke from getting out. Depending on the level of creosote buildup you have in your chimney, special tools and most likely a professional will be needed to remove the tar and build up without damaging your chimney.

2. It can be harmful to human health. Creosote is very toxic and can have a wide range of effects on you and your family. While some may just be irritating, others can be severe. You and your family may be at risk of inhaling the toxic chemical if you continue to use your fireplace with creosote buildup.

3. It is a fire hazard. Creosote is highly combustible, so if left untreated, a fire can start and quickly spread to your roof and other parts of your home. 

Things that encourage Creosote buildup:

1. Chimney Offsets/Elbows

A normal vent allows gasses from your fireplace to escape straight up the chimney with minimal contact to the walls. When a chimney flue has a bend in the piping (or an elbow), it causes the gasses to slam into the walls on its way out. When these gasses make contact with the walls, they move slower up the flue and lose momentum. This leaves more time for it to attach to the walls and create issues.

2. Exposed Venting

   

Creosote is essentially condensation. Just as the outside of a cold soda can condensates, it pulls the moisture out of the warm air and it condensates on the cold can. The same thing happens in your chimney. If your hot chimney gets exposed to the cold outside air the tar in the smoke will condense onto the walls of your chimney and you will start to have creosote buildup. 

3. Poor Maintenance

Chimney cleaning is essential to maintaining the health of your chimney and stove. It is recommended that you at least check your stove and chimney annually. Symptoms of your chimney getting plugged is your stove gets very slow, an excessive smell of smoke when a fire is burning, when you open the door smoke just rolls out, excess soot, water streaks inside of flue, and falling debris. These should all raise alarm that you might need to get your chimney cleaned. 

4. Burning the wrong type of wood

One of the biggest problems for most people is having moisture in your wood. This causes the temperature to not rise high enough and the water from the wood will bind with the fumes in the smoke and creosote can build up within your chimney walls. 

5. Incorrect Vent Sizing

 If your appliance is not connected with the proper vent system, the stove will not perform correctly and can cause gasses to build up. 

 Stages of Creosote Buildup:

1. Stage 1: Dust-like Coating

   

The first signs you will see is a light gray dust that coats the inside of your chimney. This level of buildup can be easily removed when using the right chimney brush. If you have a metal chimney, you will need a poly brush, this ensures that you don't wear down the flue. If you have a masonry chimney, you will need a steel bristle brush, this ensures that everything is removed from the mortar joints. 

2. Stage 2: Tar-like crunchy flakes

   

During this stage a semi-glossy appearance will take over the dusty coating of stage one. It can feel sticky, or tacky. You may be able to peel some of it off with your fingers, but most will stick to the walls. At this stage the buildup starts to become concerning, at this point it will take a little more effort to get the buildup removed. At this point a certified chimney sweep will need much stiffer brushes and possibly special tools to scrape off the buildup. 

3. Stage 3: Thick Coating

   

This is the final stage of the buildup where the creosote looks like tar and sticks like glue. As the chimney heats up and the creosote gets super hot it will re-liquify and drip combustible balls of tar into your fireplace. It is extremely flammable at this point and can very easily cause a chimney fire.The cleanup process of this is very difficult and will require a certified chimney sweep special tools to remove this level of buildup.