How Do You Dry Firewood and Tell If It Is Wet? Green Wood Tests

Short answer: the US EPA says firewood burns best at a moisture content of less than 20 percent. Split it, raise it off the ground and season it for at least 6 months in an airy stack with only the top covered. Wet wood is heavy, thuds when knocked and has few end cracks; a moisture meter is most reliable.

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What moisture content should firewood have?

The EPA's Burn Wise programme says wood burns best at a moisture content of less than 20 percent; the University of New Hampshire (UNH) Extension also writes that below 20% firewood burns cleanly and efficiently. According to Penn State, green wood can be well over 50% moisture. Forest Research, the UK forestry research agency, says a fresh green log has only about half the energy of a well-seasoned one; wet wood smoulders, makes tar and smoke, raises the risk of a chimney fire and blackens stove glass. For a table of moisture versus heat, see our guide How many calories in firewood?.

How can you tell if firewood is wet?

None of these signs is conclusive on its own; when several agree, you can trust them.

UNH calls the moisture meter the most reliable home method; the outside dries faster than the inside, so measuring on the bark misleads. Forest Research adds that meters only give an indication and that oven drying is the accurate method.

How do you dry stove firewood?

1. Split it. The EPA recommends burning dry, split, well-seasoned wood. Forest Research advises splitting logs to less than 10 cm diameter so moisture moves from the centre to the surface more easily.
2. Raise it off the ground. Do not stack wood straight onto soil or concrete; use pallets or bearers (Forest Research, Penn State).
3. Sun and wind. Forest Research recommends a sunny, windy spot with the prevailing wind blowing through the stack; UNH asks for a dry, ventilated stack.
4. Cover only the top. The EPA advises storing wood outdoors, off the ground, with only the top covered, noting that covering the sides traps moisture. Wood wrapped in plastic on all sides does not dry.
5. Bring it in before use. Forest Research notes that bringing cut, split logs indoors for a few days before use helps lower moisture.

How many months does firewood take to dry?

Sources give a range: the EPA at least 6 months, UNH 6–12 months, Penn State a year or more under roof and off the ground. Forest Research says reaching 20% by air drying may take two summers or more, and shows that species differ in moisture when felled; fresh oak, for example, is at 47%. So trust a measurement more than the calendar. If you bought 6-month oak (sack declaration 25-30% moisture), stack it as above and let it keep drying; for species differences see oak, beech or pine.

Where should firewood be stored?

Keep the main supply outdoors, stacked as above, and bring in only a few days' worth. The US Fire Administration (USFA) advises keeping a wood stove at least 3 feet (about 1 metre) from anything that can burn, so do not put the log basket right next to the stove. For quantities and space, see how many sacks and steres in 1 tonne.

What does it depend on?

• Piece thickness: thinly split wood dries faster.
• Species: moisture at felling varies by species.
• Stack site: sun, wind, height off the ground and open sides.
• Season: Forest Research notes that standing timber is driest in winter.

To estimate your seasonal needs use our fuel calculator; for wood versus coal, see wood or coal in a stove.

Safety: wet wood and carbon monoxide

Wet wood smoulders and makes more smoke, and all burning wood produces carbon monoxide. The EPA advises opening the stove door only to add wood, as otherwise carbon monoxide can be released into the home. The CDC describes it as an odourless, colourless gas; Türkiye's Ministry of Health lists headache, dizziness and weakness as first signs. If you suspect it, ventilate, leave the room and call 112. See stove gas symptoms and carbon monoxide detectors.

Frequently asked questions

How do you tell green firewood?

It is heavy, thuds when knocked, lacks deep end cracks and its bark holds tight. The most reliable test is a moisture meter on a freshly split face.

Can you burn wet wood in a stove?

It is not recommended. The EPA lists wet wood among things not to burn; according to Forest Research it makes tar and smoke and raises the risk of a chimney fire.

Should I wrap firewood in plastic?

Cover only the top. The EPA notes that covering the sides traps moisture.

Why does dry wood give more heat?

The water in wet wood uses heat to evaporate before the wood burns. Forest Research says a fresh log has about half the energy of a seasoned one.

Sources: U.S. EPA Burn Wise, “Best Wood-Burning Practices” (less than 20 percent moisture, at least six months, colour/weight/sound, only the top covered, door and carbon monoxide); University of New Hampshire Extension, “How can I tell if my firewood is seasoned and okay to burn?” (cracks, sound, weight, moisture meter, 6–12 months); Forest Research, “Wood as Fuel” and “Technical Supplement”; Penn State, Michael Jacobson; U.S. Fire Administration, “Heating Fire Safety”; CDC, carbon monoxide; Ministry of Health, CO poisoning.