Seasoning and storing firewood

When wood burns, the water it contains must first evaporate. That takes energy which then does not go into the room as heat. At the same time the steam cools the firebox. At lower temperatures the gases from the wood do not burn completely: more smoke, more soot and more tar form, and the tar settles on cold surfaces in the stove and chimney. These deposits can ignite – a chimney fire is dangerous.

Drying is basically a race between water moving out of the wood and the air carrying it away. Splitting increases the surface area and shortens the path the water has to travel. Airflow carries the damp air off, sun warms the stack, a roof keeps rain off and space above the ground stops moisture being drawn up from below.

How long wood needs to dry depends on species, log size, climate and storage site. Dense woods generally take longer than light ones. So fixed times cannot honestly be given – measuring is better than guessing.

Ideally the wood is cut to stove length and split soon after felling. Whole rounds with bark dry much more slowly, because the bark acts like a jacket. The storage site is ideally sunny and windy. The wood rests on pallets, timber bearers or stones, with some distance from the house wall so air can circulate behind the stack too.

Stack loosely in rows and leave the sides open. Stabilise the ends of the stack with pieces laid crosswise. Cover only the top – with a small roof or a tarp. A stack wrapped completely in a tarp does not dry; it sweats and can go mouldy.

Measure with a moisture meter on a freshly split inner face, not on the dry outside. Common recommendations give values below about 20 percent as dry enough. Without a meter there are clues: dry wood is lighter, sounds sharp rather than dull when knocked together and often shows cracks at the ends. But these signs are only rough indications.

Even well-seasoned wood produces carbon monoxide when it burns. Only heat in stoves approved by professionals whose chimney is regularly inspected and swept. A carbon monoxide alarm belongs in the room with the stove. If several people have headaches, dizziness or nausea, get outside immediately and call the local emergency number (112 in the EU).

Woodpiles can topple and cause serious injury. Stack stably and not too high, secure the ends and keep children away from the pile. Sawing and splitting have their own safety rules for axe and saw – sturdy shoes, gloves, distance from others.

Treated, painted or preserved wood, chipboard, pallets of unknown origin and rubbish are not burned. They can release toxic substances. Large woodpiles directly against the house wall may be restricted by local fire rules – check local rules.

Bring only a small supply indoors, ideally a few days before use. That way surface moisture can still dry off and the wood reaches room temperature. Keep it at a distance from the stove, not right beside or underneath it.

Large amounts of wood do not belong in living spaces. They bring in moisture, sometimes insects and dust, and they add to what could burn. A woodshed with a roof and open slatted walls is the long-term solution for larger amounts.

Taking wood is not allowed everywhere. In the forest, all wood belongs to someone, even what lies on the ground. Only take wood you are allowed to buy or collect – check local rules. Some countries also have rules on wood moisture and on emissions from small stoves.

Dry wood is better not only for warmth but also for the neighbourhood: it makes less smoke and fine dust. And it saves work, because you need less wood for the same warmth. Anyone preparing for a possible heating failure therefore builds up the supply early – freshly bought wet wood is of little use the same winter.