By Daniel Watkins, Noble Chimney Sweepers.
Late August is when firewood gets delivered and stacked, and it is also when the single biggest cause of creosote buildup gets set in motion. Wet wood is not just a slow starter. It is the reason a flue that was clean in October can be dangerously coated by February.
Why wet wood coats a chimney
Freshly cut wood is roughly half water by weight. Burning it means the fire spends its energy boiling that water off before it can raise the firebox to a temperature where the smoke burns cleanly. What escapes instead is cool, unburned smoke loaded with tar. It rises into a flue that is also running cool, condenses on the liner walls, and hardens there. Do that all winter and you have built a fuel deposit inside the chimney.
What “seasoned” actually means
Seasoned wood has dried until its moisture content sits at or below roughly twenty percent. That is a measurement, not a season. Wood split and stacked in spring is usually ready by fall; wood cut in July and delivered in September generally is not, no matter what the seller calls it.
How to check it without a meter
Seasoned splits are noticeably lighter than they look, show checking cracks radiating from the center of the end grain, and knock together with a sharp clack rather than a dull thud. The bark often loosens. Green wood hisses at the cut end when it burns and leaves the glass sooted within minutes.
How to check it with one
An inexpensive pin moisture meter settles the argument. Split a piece open and test the freshly exposed inner face, not the weathered outside, which always reads dry.
Stacking that works through a Mokena winter
Wood dries from the ends and from the split faces, and it dries fastest with air moving through the pile. Stack it off the ground on pallets or rails, in single rows rather than a solid block, somewhere it gets sun and wind. Cover only the top. A tarp wrapped down the sides traps moisture and turns the stack into a humidifier, which is a common and avoidable mistake on the wooded lots around town. If you want the rest of what we handle nearby, see our chimney and dryer vent service in Mokena.
What to burn, and what to keep out
Well-seasoned hardwood such as oak, hickory, ash, or hard maple gives the longest burn per load. Oak needs the most drying time, often two years. Softwoods light easily and are fine for kindling but burn fast. Keep pressure-treated lumber, painted or stained wood, pallets of unknown origin, driftwood, and cardboard out of the firebox entirely; they put chemicals and fast-cooling smoke into a flue that was not designed for either.
What we find when wet wood has been burned
A season of green wood typically leaves a thick, flaky or tar-like deposit that a routine sweep can still remove. Push it further and it bakes into a hard glaze that no brush touches, and the repair becomes chemical treatment or relining rather than cleaning. That is the whole argument for burning dry wood and booking a chimney sweeping before the heating season rather than after. If it has been a while, or you have inherited a fireplace you do not know the history of, a camera inspection tells you which category you are in.
Noble Chimney Sweepers is certified, bonded and insured, owner-operated, and available seven days a week from 7 AM to 7 PM. Daniel has been doing this work for fourteen years and quotes the price up front before anything starts. Call (708) 432-5747, browse the full list of services, or check current rates on our pricing page.
Frequently asked questions
How long does firewood need to season?
Most split hardwood needs six to twelve months stacked in the open. Oak commonly needs closer to two years. Softwoods can be ready in a few months.
Is kiln-dried wood worth it?
It burns cleanly and is consistent, which is genuinely useful if you have no space or time to season your own. Whether the premium is worth it depends on how much you burn; a small number of fires a year is a reasonable case for it.
Can I speed up drying by stacking wood in the garage?
Not really. Wood needs moving air more than it needs shelter, and an enclosed garage gives it neither airflow nor sun. It also brings insects indoors. Outside with a covered top dries faster.
Does burning hot fires clean the chimney?
No. A hot fire produces less new creosote, but it does not remove what is already on the liner, and deliberately overfiring to burn deposits out is how chimney fires start.
Why does my glass door black over so quickly?
Sooted glass within an hour or two of lighting almost always means wet wood, a smoldering low-air burn, or both. Dry wood burned with adequate air keeps the glass mostly clear.
Is it safe to burn wood that got rained on?
Surface water on already-seasoned wood is not a problem. Bring the splits inside a day ahead and the outside dries off. Water that soaked into unseasoned wood is a different matter.
How can I tell if creosote has already built up?
Signs include a strong campfire odor in the room on humid days, dark flakes in the firebox, and a fire that is hard to start and keeps dying back. Only a look up the flue confirms how thick it is.
Do I still need a sweep if I burn only dry wood?
Yes. Dry wood slows buildup considerably, it does not stop it, and a sweep visit also checks the cap, damper, liner, and crown. Once a year is the standard interval for a regularly used fireplace.
Published August 30, 2026