Firewood Moisture: How to Measure It and Store Logs Correctly

A log can look dry on the outside while still holding plenty of moisture at its centre. That hidden water makes fires harder to light, reduces useful heat and encourages smoky combustion. Checking firewood moisture content before burning—and giving logs the right storage conditions—helps you avoid these problems.

The most useful check is simple: split a sample log and measure the freshly exposed wood. Combine that habit with a raised, ventilated log store, and you can judge your fuel by its condition rather than its appearance or delivery date.

What moisture content should firewood have?

For most domestic wood stoves and fireplaces, a practical target is around 15–20% on a suitable wood moisture meter, while following the appliance manufacturer’s fuel guidance. Logs reading above 20% generally need further drying.

A meter provides an estimate, so a reading close to the limit deserves another check. Temperature, wood species and how you position the pins can all affect the result.

Wet wood uses energy to evaporate water before it can deliver useful warmth. It also encourages incomplete combustion and tarry deposits in the flue. The Dutch fire service’s guidance on preventing chimney fires identifies wet wood as a contributor to creosote formation and recommends burning clean, dry fuel.

Dry wood still produces air pollution. Moisture control also needs to sit alongside correct stove operation and regular chimney maintenance.

How to measure a freshly split log

A basic pin-type meter intended for wood is suitable for routine household checks. Read its instructions first: pin depth, grain direction, temperature correction and wood settings can differ between models.

1. Take samples from different places

Choose several logs—ideally at least five—from different parts of the stack or delivery. Include larger pieces and logs from less exposed positions.

Testing one small log from the sunny edge can give a misleading impression of the whole supply.

2. Account for cold wood

Frozen wood cannot be tested reliably with a typical resistance meter. Let sample logs thaw and approach room temperature before splitting and measuring them, or apply the manufacturer’s temperature correction where appropriate.

Keep these samples away from the stove and other heat sources.

3. Split through the centre

Split the log lengthways to expose its interior. Measure promptly on that newly revealed face.

The bark, weathered outer surface and exposed ends may have different moisture levels from the centre. Pressing the pins into an intact log’s outside surface can therefore miss a wet core.

4. Measure the fresh inner face

Select the meter’s wood mode and the appropriate species setting if available. Press both pins firmly into sound wood near the middle of the freshly split face, following the specified depth and orientation.

Avoid knots, cracks and resin pockets. Take readings at two or three positions rather than relying on one contact point.

5. Compare the results

Record the readings and repeat the process with the other samples. If some logs remain above the recommended range, give that batch more drying time and test again.

Check which moisture scale your meter uses when comparing readings with supplier information; timber meters and firewood specifications do not always express the percentage on the same basis.

How to recognise poorly seasoned wood

Appearance offers clues, but it cannot confirm that a log is ready to burn. Wood that needs more drying may:

• Feel unusually heavy compared with a dry piece of the same species and size.
• Have a noticeably damp interior when freshly split.
• Produce a dull thud when two pieces are knocked together.
• Retain tightly attached bark.

Cracked ends, loose bark and a sharper knocking sound can suggest drying, but the centre may still be wet.

Hissing, difficulty staying alight and rapidly blackening stove glass can also accompany damp fuel. These symptoms have other possible causes, including insufficient combustion air or poor chimney draught, so confirm moisture with a meter rather than diagnosing from the fire alone.

How to store firewood for effective drying

Good storage lets moisture escape while limiting fresh water entering the stack. In the Dutch climate, both airflow and rain protection matter.

Raise the stack and leave room for air

Use a stable rack or bearers to keep logs clear of soil and standing water. Allow air to reach beneath the stack as well as through its sides.

Choose an open, breezy position with some sunlight where possible. Leave a ventilation gap behind the wood instead of packing it against a wall. A single row dries more evenly; if you need several rows, leave spaces between them.

Stack securely without wedging every gap full. Split large rounds into pieces suitable for your appliance before seasoning, since thick, unsplit logs dry slowly.

Protect the top from rain

A roof with an overhang provides useful protection while leaving the sides ventilated. If you use a tarpaulin, secure it over the top and keep the sides open.

Wrapping the entire pile in plastic restricts airflow and can trap condensation. Likewise, a closed, poorly ventilated shed may keep rain out while slowing drying.

Allow enough time

Seasoning takes months, and dense hardwoods may need 18–24 months or longer under ordinary outdoor conditions. Species, log thickness, weather and storage arrangement all influence the time required.

Label batches by stacking date and keep newer wood separate from logs already tested as dry. Recheck before use, including kiln-dried logs that have subsequently been exposed to damp storage.

Bringing logs indoors

Bring in a small supply a day or two before use, once the wood is already properly seasoned. This can help surface dampness disappear, but it will not dry a wet centre overnight.

Use a basket or rack outside the appliance’s required clearance distances. Keep logs off the hearth area where sparks could reach them, and never dry them on top of a stove.

Practical firewood checklist

• Moisture: Check freshly split interiors from several representative logs.
• Preparation: Split large pieces before stacking.
• Ground clearance: Raise the bottom row above soil and standing water.
• Airflow: Leave gaps beneath, behind and between rows.
• Rain protection: Cover the top while keeping the sides ventilated.
• Stability: Keep the stack secure and accessible.
• Rotation: Separate new batches from tested, dry wood.
• Indoor supply: Bring in only a small amount of seasoned wood, keeping it clear of heat and sparks.