Firewood: burn it at 20% moisture or less, and get the chimney checked every year

Why the line is 20%

EPA’s Burn Wise page says wood burns best at a moisture content of less than 20 percent and tells you to test it with a wood moisture meter before you burn it. An EPA handout puts the most efficient range at 15% to 20%, and notes that wood from a freshly cut tree can be more than 50% water. [S1] [S4]

The water has to boil off before the wood burns well. EPA says too much water lowers the temperature in the stove, so the wood doesn’t burn completely, and that incomplete burning sends smoke up the chimney and creates creosote. EPA’s meter flyer adds that dry wood cuts creosote buildup, which means fewer chimney fires. [S3] [S4]

The Chimney Safety Institute of America describes creosote as black or brown, and crusty, tar-like or shiny. Whatever form it takes, CSIA calls it highly combustible, and it lists unseasoned wood, a restricted air supply and a cooler chimney as things that speed its buildup. [S13]

A reading taken on the outside of a log doesn’t count here. The next section covers where to push the pins in.

How to test a piece

• Split it first. Pick a piece, split it, and test the newly split side, ideally within 24 hours. EPA says this tests the inside of the wood, not just the outer layer. University of Maryland Extension says to measure the middle of a freshly split piece. [S3] [S4] [S6]
• Pins along the grain. Push the meter’s prongs in so they run parallel with the grain, and test two or three spots for the most accurate reading. Follow your meter’s own instructions too. [S3] [S4]
• Mind the cold. EPA’s handout says to test when it’s 50°F to 90°F outside if you can, because colder wood gives a lower reading than it should. A cold piece that reads just under 20% may be wetter than it looks. [S4]
• No meter yet? EPA says seasoned wood is darker, weighs less and sounds hollow when you knock two pieces together. Those are clues, not a number. UMD Extension says a meter on a fresh split is the only way to know for sure. [S1] [S5] [S6]

Buying wood? UMD Extension suggests asking when it was split, and splitting a random piece to test it before the load is unloaded. It calls wood over 30% not seasoned. [S6]

Split, stack, cover, wait

EPA’s Wet Wood is a Waste brochure lays out four steps. Split the wood, in sizes that fit your stove but no larger than 6-inch wedges. Stack it away from buildings, off the ground on rails, in a single row with the split side down. Cover the top, leaving space between the cover and the wood, and keep the sides open so air moves through. Then wait. [S5]

How long depends on the wood. The brochure says softwoods take about 6 months and hardwoods about 12. EPA’s web page says at least six months, and its meter flyer says 6 to 12. Splitting matters a lot: in a University of Maryland study, uncovered hickory left in unsplit lengths was still over 30% moisture after a year, while split pieces dried to about 20% in 6 months. [S1] [S3] [S5] [S6]

EPA also asks you to buy and burn locally cut firewood, so you don’t carry invasive forest pests to your property. [S1]

Burning it safely

• Start clean. EPA says to start fires with dry kindling or all-natural fire starters, and never with gasoline, kerosene or charcoal starter. [S1]
• Burn only clean, dry wood. EPA’s do-not-burn list includes household trash, cardboard, plastics, foam, colored ink on magazines and boxes, coated, painted or pressure-treated wood, ocean driftwood, plywood, particle board, wood with glue on or in it, and wet, rotted, diseased or moldy wood. [S1]
• Check before using fake logs. EPA says many wax and sawdust logs are made for open fireplaces only, so read your stove or insert instructions first. If you use manufactured logs, it suggests ones made of 100 percent compressed sawdust. [S1]
• Keep it hot. EPA says a smoldering fire is neither safe nor efficient, and to keep stove doors closed except when loading or stoking, since carbon monoxide can get into the house. [S1]
• Screen and space. Keep a glass or metal screen in front of the fireplace, and keep anything that can burn at least 3 feet away. NFPA also asks for a 3-foot kid-free zone around a stove. [S8] [S9] [S10]
• Put it out. USFA says to put the fire out before you go to sleep or leave the house. [S8]

On high-smoke days, EPA asks you to check your local air quality forecast and any burn ban before you light a fire. [S1] [S5]

What are you seeing?

Pick the closest match to highlight what the sources say to do next.

Once a year: the chimney check

Every safety source here says the same thing. USFA, NFPA and CPSC say to have a professional inspect, and clean as needed, the chimney and the fireplace or stove each year. EPA says chimney cracks can let smoke into your home or expose parts of the chimney to enough heat to start a fire. [S2] [S7] [S9] [S12]

The stakes are real. CPSC estimates fireplaces and chimneys are involved in an average of 15,400 fires a year, with an average of 20 deaths and 80 injuries a year, from 2019 to 2021. NFPA says larger fireplace and chimney fires were 6% of home heating fires from 2020 to 2024 but caused nearly a fifth (19%) of the direct property damage. And CSIA says most chimney fires go undetected until a later inspection, even though they can reach temperatures high enough to damage the chimney and nearby parts of the house. [S11] [S12] [S13]

Look for credentials. EPA points to the Chimney Safety Institute of America to find a certified sweep, and to the National Fireplace Institute, which certifies hearth technicians. CSIA recommends a CSIA Certified Chimney Sweep. [S2] [S13]

A wood fire is also a carbon monoxide source. NFPA asks for CO alarms outside each sleeping area and on every level, and CPSC says to test alarms every month. Our CO alarm placement guide has the details. [S10] [S12]

Before the first fire

Run through this once each fall. Our fire extinguisher guide covers which label to look for. [S1]

Quick answers