What Causes Creosote Buildup — And How Firewood Plays a Role
- Michelle Persolja
- Dec 29, 2025
- 4 min read
If you use a fireplace or wood stove, creosote is something you’ve likely heard about — often with plenty of warnings but not much explanation. While it’s a common issue, there’s a lot of misunderstanding around what actually causes creosote buildup and the role firewood plays in it.
Let’s break it down in simple terms so you can burn safely and with confidence.
What Is Creosote?
Creosote is a dark, sticky residue that forms inside chimneys and flue pipes when smoke cools and condenses. Over time, it can build up in layers ranging from flaky soot to thick, tar-like deposits.
Why it matters:
Heavy creosote buildup restricts airflow
It reduces heating efficiency
In severe cases, it can increase the risk of a chimney fire
Creosote doesn’t appear overnight — it’s the result of repeated burning conditions over time.
The Three Main Causes of Creosote Buildup
1. Burning Firewood With Too Much Moisture
Wet or partially dried firewood produces more smoke and steam. When that smoke cools inside the chimney, it leaves behind unburned particles that cling to the flue walls.
Common signs include:
Wood that sizzles or steams when burning
Excessive white or gray smoke
Difficulty maintaining a steady flame
The higher the moisture content, the more smoke is produced — and the greater the creosote potential.
2. Low-Temperature, Smoldering Fires
Slow, low fires may seem efficient, but they often don’t burn hot enough to fully combust gases released from the wood.
This happens when:
Airflow is restricted too much
Fires are kept very small for long periods
Damp wood prevents the fire from reaching proper temperatures
Cool smoke is more likely to condense inside the chimney, accelerating creosote formation.
3. Poor Draft or Restricted Airflow
If smoke can’t move freely up and out of the chimney, it lingers and cools.
Contributing factors can include:
Closed or partially blocked dampers
Dirty or narrowed flue liners
Improper stove operation
Even good firewood can lead to creosote if airflow isn’t adequate.
How Firewood Moisture Directly Contributes to Creosote
Firewood with excess moisture must burn off water before it can produce heat. That process:
Lowers fire temperature
Increases smoke output
Releases more unburned gases
When you hear firewood sizzling or hissing, that’s water turning into steam — a clear sign the wood isn’t as dry as it needs to be for clean burning.
It’s also important to note that firewood can reabsorb moisture after it’s been dried if it’s stored exposed to rain or snow. In those cases, the outside of the wood may be wet even if the inside is still relatively dry, which can still cause sizzling and excess smoke at first.
Signs Creosote May Be Building Up
Watch for:
Strong smoky or tar-like odors
Black flakes or shiny residue inside the stove or fireplace
Excess smoke entering the room
Fires that struggle to burn cleanly
If you notice any of these, it’s a good idea to have your chimney inspected.
How to Reduce Creosote Risk
You don’t need special equipment or complicated routines — just good burning habits.
Use properly dried firewood
Store firewood off the ground and protected from precipitation
Burn fires hot enough to maintain clean combustion
Avoid long periods of smoldering fires
Have your chimney inspected and cleaned regularly
These steps work together to keep your system safer and more efficient.
Choosing Quality Firewood Makes a Difference
No matter how firewood is dried, the most important factor is moisture control and consistency. Firewood that is properly dried ignites more easily, burns hotter, and produces less smoke — all of which help reduce creosote buildup.
At The Firewood Co., we focus on quality at every step. Our naturally seasoned firewood is allowed adequate time to dry and is handled and stored to minimize re-absorbing moisture. Our kiln-dried firewood goes through a controlled drying process where heat and airflow are carefully managed to bring moisture levels down evenly throughout the wood.
Kiln drying allows us to reduce moisture more quickly and consistently, especially in dense hardwoods, while seasoning relies on time, airflow, and proper handling. In both cases, we monitor moisture levels and don’t sell firewood until it meets our standards.
The goal is the same: clean-burning, reliable firewood that produces less smoke and helps keep chimneys cleaner.
What to Expect When Burning Quality Firewood
When you burn properly dried, quality firewood, you should notice:
Easier ignition with less effort to get the fire started
Brighter, more active flames
Less visible smoke once the fire is established
Minimal sizzling or hissing
More consistent heat output
It’s normal for occasional surface moisture to burn off if wood has been stored and exposed to moisture, but quality firewood should not struggle to stay lit or produce excessive smoke throughout the burn.
Several customers have shared that after switching to our firewood — both seasoned and kiln-dried — their chimney professionals noticed noticeably cleaner chimneys during routine cleanings.
What happens if you bought firewood that is not seasoned?
For customers who bought firewood from another seller that is too wet to burn cleanly, we offer Dry My Wood™, our professional kiln-drying service. This service allows customers to have their firewood dried in a controlled kiln environment, reducing moisture content and helping it burn more safely and efficiently.
When to Call a Chimney Professional
If you’re unsure about your chimney condition, notice heavy creosote buildup, or experience unusual smoke behavior, contact a certified chimney professional. Routine inspections are one of the best ways to ensure safe operation year after year.
Final Thought
Creosote isn’t caused by one single factor — it’s the result of moisture, temperature, and airflow working together. Understanding how firewood quality plays a role helps you make safer choices and enjoy cleaner, more efficient fires.
Stay warm,
Nick & Michelle Persolja
The Firewood Co.
Dry My Wood™
37859 Stevens Blvd
Willoughby, OH
Seasoned & Kiln-Dried Firewood Always in Stock!
We proudly serve Lake, Geauga, Cuyahoga, Lorain, Summit, Medina, Portage, Trumbull, Ashtabula, and Mahoning Counties.
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