Firewood, explained.
Firewood is sold in a unit most people can't picture, dried to a standard nobody prints on the receipt, and priced by species that all look the same in the back of a truck. This page explains how it's actually measured, how much you actually need, and how to tell dry wood from wet — before you spend money on it.
A cord is 128 cubic feet. Everything else is a negotiation.
In Illinois, firewood is sold by the cord or a fraction of a cord — and nothing else. A cord is a fixed volume of neatly stacked wood, 128 cubic feet, and it does not change based on who is selling it or what they load into the truck.
The part nobody mentions
The Illinois Department of Agriculture is direct about this: The use of terms such as "truckload," "face cord," "rack" or "pile" as the method of sale of firewood is not allowed.
Firewood in Illinois must be sold by the cord or a fraction of a cord.
We are not telling you this to make anyone the villain. "Face cord" is genuinely how the whole Chicago market talks, and plenty of honest sellers use it out of habit. But it is a unit with no fixed size, which means two quotes using it are not comparable. A face cord of 20-inch splits holds two-thirds more wood than a face cord of 12-inch splits — 53 cubic feet against 32 — and both can be advertised at the same price.
What to ask before you pay
The state also recommends getting a receipt that lists the seller's name, address and phone number; the price, amount, and type of wood; and the delivery vehicle's license number. That is not an unreasonable ask, and a seller who won't put the quantity in writing has told you something useful.
- "What fraction of a cord is that?" Not "how big is your face cord." Convert it to cords before you compare prices.
- "How long are the splits?" Sixteen inches is the North Shore default and fits most fireplaces. Measure your firebox first — an 18-inch split in a 20-inch box leaves no room to load it.
- "Will it be stacked, or dumped?" Volume can only be verified stacked. Loose-thrown wood takes up roughly 40 percent more space than the same wood stacked — a cord of 16-inch splits fills about 180 cubic feet dumped in a heap. A big pile in the driveway is not evidence of a big delivery.
- "What species, and when was it split?" Both answers matter more than the price. The next two sections explain why.
If the delivered pile looks short, stack it and measure it before you burn any of it, and photograph it. Once it's been burned there is nothing to measure.
How much do you actually need?
Most people over-order the first year and under-order the second. Three questions get you close enough to buy with confidence.
Firewood estimator
Based on a typical North Shore burning season — roughly November through March.
This is an estimate, not a measurement. Real consumption swings with how cold the winter runs, how dry the wood is, and how hot you like the fire. Wet wood burns through faster because a share of every log's energy is spent boiling off its own water. If you're between two sizes, take the larger one — properly stacked firewood keeps for years, and next season's wood is already paid for.
"Seasoned" is a marketing word. Twenty percent is a number.
Nothing about firewood matters more than how dry it is. Not species, not price, not how it looks in the truck. Wood at 30 percent moisture and wood at 18 percent are two different fuels.
What happens when wood is wet
Water in a log has to boil off before the wood can burn. That energy comes out of your fire, not out of the air — which is why wet wood hisses, smolders, blackens the glass, and never quite gets going. You are paying for wood and burning a portion of it as steam.
The smoke from an under-dried fire is cooler and heavier with unburned volatiles. Those condense on the inside of a cool flue as creosote, a tarry deposit that accumulates layer by layer and is itself combustible. Burning wet wood is the single most reliable way to build creosote in a chimney. It is also the easiest variable to control.
A freshly cut log can be more than half water by weight. Stacked properly and given enough time, air-dried wood should come down under 20 percent, and that is the number to aim for — it is entirely achievable outdoors in Illinois. The catch is that "seasoned" gets applied just as freely to wood that has spent three months in a shaded heap, which can still be sitting at 25 or 30 percent. Air-dried and kiln-dried can both be excellent fuel. Only one of them arrives with a number attached.
Four ways to check it yourself
- Look at the ends. Dry splits check and crack radially from the center, like a wheel. Fresh-cut ends are smooth and often damp to the touch.
- Pick it up. Dry wood is noticeably lighter than green wood of the same species and size. A cord of green oak can carry hundreds of pounds of water.
- Knock two pieces together. Dry wood cracks — a sharp, hollow report. Wet wood thuds.
- Split one and meter it. A moisture meter costs less than a delivery. Split a piece and test the fresh inside face, not the weathered outside. Under 20 percent is ready. Over 25 percent needs another summer.
Seasoned vs. kiln-dried
Seasoned means air-dried outdoors for a period of time — but no one regulates how long, so the word alone tells you nothing. Ask when it was split. Kiln-dried means heated in a controlled chamber to a verified moisture content. It costs more, arrives ready, and doesn't need a year of your patio.
One distinction worth knowing: drying wood to a moisture target and certified heat treatment are not the same process. Certification requires the core of the wood to reach 140°F for 60 minutes and carry an approved label — that is what legally allows firewood to travel. "Kiln-dried" on its own does not guarantee it.
Not all wood is worth the same money.
Heat output tracks density: heavier wood holds more energy per cubic foot, so a cord of hickory carries nearly twice the heat of a cord of white pine. Dense wood also takes far longer to dry, which is why the best firewood has to be bought a year or two ahead — or bought already dried.
| Species | Heat per cord (M BTU) | Air-drying time | Splits | Verdict |
|---|
Heat and splitting figures are from the University of Kentucky Forestry firewood properties table, stated as millions of BTU per full cord at 20 percent moisture content. Published BTU charts disagree with each other by ten percent or more depending on their moisture assumptions, so we use one source throughout rather than mixing them — the ranking is what matters, and it is consistent. Drying times are general guidance and assume split wood, properly stacked and top-covered in an open, sunny location.
For a long, hot fire
Oak, hickory, hard maple, black locust, honey locust. Dense, slow-burning, excellent coals. All of them want one to two years of drying, so buy them a season or two ahead — or buy them already dried.
For wood you need this year
Ash and cherry. Both dry unusually fast for their heat output — often ready in six to twelve months — and ash splits cleanly and lights easily. Ash is the practical answer for anyone who didn't plan ahead.
For a fire you'll actually sit near
Cherry and hard maple burn clean with a mild, pleasant smell. Birch lights beautifully but burns fast, and its papery bark should come off before storage — it traps moisture against the wood.
What to leave on the truck
Cottonwood, box elder, willow, and silver maple carry little heat for their bulk. Pine and other softwoods light easily and are fine for kindling, but they burn fast and resinous — poor value as a primary indoor fuel.
Wood doesn't stay dry on its own.
You can buy properly dried firewood and ruin it in a month by stacking it wrong. Wood re-absorbs moisture from the ground, from rain, and from air that can't move. Stacking is not housekeeping — it's the second half of seasoning.
Get it off the ground
Four inches of clearance is enough. A rack, pallets, or two lengths of pipe all work. Wood stacked directly on soil or grass wicks water up from below and rots from the bottom row.
Cover the top only
A tarp over the top keeps rain out. A tarp down the sides traps humidity in and turns the stack into a greenhouse. Leave the ends and sides fully open to the air.
Sun and wind, not shade
Pick the most open, sunniest, breeziest spot you have and orient the stack so prevailing wind blows across the face of it. Single rows dry dramatically faster than deep piles.
Not against the house
Keep the main stack away from the foundation and siding. A wood pile against the house is an invitation to carpenter ants, termites, and mice, and it holds moisture against your walls. Bring in a few days' worth at a time.
Split it before you stack it
Bark is designed to keep water in. Rounds left unsplit can sit for two years and still be wet in the middle. Splitting exposes end grain and open faces, which is where nearly all the drying happens.
Oldest wood in front
If you're carrying two seasons at once, burn the older stack first and let the new one keep drying. Properly stored firewood stays good for years — there's no penalty for being a year ahead.
A good fire is a hot fire.
Smoldering is what causes most of the problems people blame on their chimney. A fire that burns hot and clean produces less smoke, less creosote, and more of the heat you paid for.
Do this
- Build it top-down. Large splits on the bottom, smaller above, kindling and starter on top. It lights from the top, warms the flue first, and smokes far less than a bottom-lit fire.
- Warm the flue before you light. On a cold day, hold a rolled newspaper torch up in the damper opening for a minute to reverse a cold downdraft.
- Open the damper fully to start. Give it real air until the fire is established.
- Crack a window if the fire won't draw. Tight modern houses can starve a fireplace of air, especially with an exhaust fan running.
- Let ash build to about an inch. A shallow ash bed insulates the firebox floor and helps hold coals.
Not this
- Don't damp it down to make it last. Choking the air is how you turn a fire into a creosote generator. Burn less wood, not slower wood.
- Don't burn construction lumber, pallets, or anything painted, treated, or glued. Treated wood releases genuinely toxic compounds, and the residue is corrosive to a flue.
- Don't burn cardboard, wrapping paper, or Christmas trees. They flare hot, throw burning fragments up the flue, and deposit heavily.
- Don't use a fire to get rid of trash. A fireplace is an appliance, not an incinerator.
- Don't start the season without an inspection. Wood-burning appliances should be inspected annually, and the results should tell you whether the flue is clear before the first fire — not after.
Where the chimney comes in
Timber Monkey is the firewood side of Chimney Monkey, which has been inspecting and repairing chimneys on Chicago's North Shore since 2017 out of Buffalo Grove. The reason we care this much about moisture content is that we spend the other half of the year looking at what wet wood leaves behind in a flue. Dry wood is the cheapest chimney maintenance there is.
Buy it close to where you'll burn it.
Firewood is one of the main ways destructive forest insects travel. A beetle that could never fly across a county rides along in a log and gets unloaded next to a healthy tree. Emerald ash borer reached Illinois that way, and it has since killed ash across the region — which is a large part of why so much ash firewood is available here now.
In Illinois this is not just good practice — it is in the administrative code. State rules prohibit bringing untreated firewood into Illinois from outside the state, and prohibit buying, selling, or possessing untreated firewood more than 50 miles from where it was cut. "Treated" has a specific meaning: the core of the wood reached 140°F for a full hour, and the wood carries approved labeling. Several northern Illinois counties are additionally under a spongy moth quarantine that restricts moving firewood out of the affected area.
On Illinois DNR properties, firewood from more than 50 miles away is not permitted unless it carries USDA or State of Illinois certification, and conservation police can confiscate it. Individual forest preserves and campgrounds set their own rules on top of the state's — some prohibit outside firewood entirely — so it is worth a phone call before you load the car.
The practical rule is short: buy it within about 50 miles of where you'll burn it, or buy it certified heat-treated. If you're taking wood camping, buy it at the destination and burn all of it before you leave. Don't haul the leftovers home, and don't haul a load up to the cabin in Wisconsin — that's the trip the beetles are waiting for.