Green vs Seasoned Firewood (Moisture Test)
Seasoned firewood is commonly considered ready to burn when its moisture content is 20% or less, measured on a freshly split interior face. A dry-looking bark or end grain can hide a wet center. Test several representative pieces with a suitable, correctly set meter, record the results, and keep seasoning any wood that reads high.
Firewood testing is useful whether you heat with one species or several. It helps you decide which stack is ready, which needs more time, and whether a low meter reading reflects the log’s interior or only a dry surface. That matters because wet wood can burn poorly and produce more smoke, while carrying and storing wood takes real effort.
In my work with firewood, I treat a moisture reading as a sample, not a verdict on an entire pile. Wood dries at different rates depending on species, piece size, airflow, sun, and exposure to rain. A reliable check starts with the right test surface and enough samples to catch that variation.
Equipment Setup and Safety Preparation
A moisture test needs a suitable wood meter and a representative piece of firewood. A pin-style meter reads electrical resistance between its pins and estimates moisture content; settings and limits vary by model. Check the manual before testing so you know which species and temperature settings to use and what the displayed percentage means.
Choose and set up the meter
A meter with a species setting can improve the reading when you select the right wood type. Some meters also require a temperature correction when the wood is outside the device’s reference range. Follow the manufacturer’s instructions rather than guessing at a correction or applying one meant for another meter.
Check the meter’s stated moisture-content basis, too. Moisture content may be expressed on a dry-weight or wet-weight basis, and devices may differ in how they display it. The commonly used firewood target is 20% or less, but make sure you are comparing your reading with guidance that uses the same basis.
Prepare a test piece safely
You do not need a chainsaw if a splitting maul or other suitable tool can expose fresh interior wood safely. If a saw is needed to buck a piece, follow its manual and wear chainsaw-rated leg protection, a helmet with face and eye protection, hearing protection, gloves, and boots. Secure the wood, clear the work area, and keep bystanders away.
Before cutting, check the saw, chain brake, and chain tension. The bar, chain pitch, gauge, drive-link count, fuel mix, and bar oil must match the saw manufacturer’s specifications. There is no universal bar-to-engine size ratio or fuel mix for all saws. If the chain is dull, poorly tensioned, or mismatched, stop and correct the setup. Never force it through wood to get a sample.
Field Sampling and Moisture-Test Procedure
A useful sample comes from a freshly split face, not the bark or the end of an unsplit log. Testing only an exposed exterior can produce a low reading even when the center remains wet. Sample several pieces from different parts of the stack, then use the results together to judge readiness.
Test the interior, not the surface
- Select a representative piece from the stack. Include different sizes or positions in the pile if they may have dried at different rates.
- If a saw is needed, operate it according to its manual to buck the piece safely. Stop the saw before handling the wood or meter.
- Split the piece to reveal a fresh interior face. This exposes wood that was not directly dried by sun and airflow.
- Set the meter for the species and temperature as directed. Place the pins on the fresh split face as the meter instructions specify.
- Take at least three readings on each of several representative splits. Record the species, stack location, date, and readings.
Pin placement and depth affect results, so use the method stated in the meter manual. Avoid relying on bark, end grain, or an old, weathered split face. Those surfaces may not reflect the moisture in the interior you plan to burn.
Read the batch, not just one piece
| What you find | What it suggests | What to do |
|---|---|---|
| Several interior readings are at or below 20% | Sampled wood meets the common seasoning target | Check more pieces before treating the whole stack as ready |
| Readings vary widely across pieces | Drying is uneven, or samples differ by size or location | Test additional pieces; keep wetter wood separate |
| Many readings are above 20% | The batch is still too wet by the common target | Continue seasoning and retest later |
| Surface looks dry but a fresh split reads high | The outside dried faster than the interior | Do not judge by appearance; give the wood more time |
A single low reading does not prove that a stack is seasoned. A consistently high result across representative pieces is a clear reason to keep drying the batch. If one piece reads high while others do not, sample more wood before making a decision.
Practical field examples
These examples show how to apply the method; they are not fixed drying-time rules. A small, well-spaced split near the top of a ventilated stack may dry sooner than a larger round from a sheltered or crowded section. Test both rather than assuming that one reading represents the other.
Likewise, a piece can look dry at the ends yet show a higher reading on a fresh interior face. That difference is why I split before testing. When the readings disagree, I record where each piece came from and retest additional splits instead of averaging away a potentially wet section.
Meter Care, Verification, and Result Interpretation
A meter is a measuring tool, not a guarantee that every log in a stack has the same moisture content. Use it consistently, keep its pins and body in good condition, and follow its instructions for settings, temperature limits, and checks. Repeatable readings from several interior faces are more useful than a single precise-looking number.
Make readings more dependable
Take readings on several pieces from different stack locations, such as the outer edge, middle, and lower rows where accessible. Do not treat a reading from one unusually small or unusually dry split as proof that larger pieces are ready. Note the date and retest later if results are borderline or inconsistent.
Keep the meter clean and store it as the manufacturer directs. Inspect pins for damage or buildup, and use any built-in check or reference method described in the manual. A meter’s display resolution does not mean its reading is exact; use the stated accuracy and limits when interpreting close results.
Avoid common testing errors
- Do not test bark or rely on an unsplit log’s outer surface.
- Do not use end grain or an old, weathered surface as a substitute for a fresh split face.
- Do not declare a stack seasoned from one low reading.
- Do not compare readings without checking species settings, temperature guidance, and moisture-content basis.
- Do not keep cutting with a saw that is dull, incorrectly tensioned, or fitted with mismatched parts.
If readings remain high, season the wood longer and improve airflow and rain protection. Wet wood can lead to poor combustion and excess smoke; burning it may also contribute to creosote buildup in a chimney. A moisture test helps reduce that risk, but it does not replace safe burning practices or regular chimney inspection.
Firewood Storage and Seasonal Retesting
Storage affects how well split wood can continue drying. Keep firewood off the soil, protect the top from precipitation, and leave the sides open to airflow. After changing the stack or allowing more drying time, retest fresh interior faces rather than assuming that a certain number of months guarantees readiness.
Stack for airflow and protection
Split wood exposes more surface area than an unsplit round, which helps it dry. Stack pieces so air can move around them, keep the stack raised off soil, and cover the top against rain or snow while leaving the sides open. A cover that traps moisture around the stack can work against drying.
Keep wetter wood separate from wood that has passed the test. Marking stacks with the species, split date, and test date makes it easier to track what is ready and what needs another check. Drying time varies, so use measured results rather than a calendar alone.
Retest before burning
Retest after additional seasoning, especially if the first readings were above 20% or varied widely. Choose new representative pieces and split them to expose fresh interior wood. If several readings remain above the target, continue drying; if results are consistently at or below it, the sampled wood meets the common threshold.
Bottom line: split first, measure the fresh interior, and sample more than one piece. Keep the settings and readings with the stack so you can make a clear decision later.
Frequently Asked Questions
These short answers cover common questions about testing and judging firewood. For the best result, use the meter’s instructions and test more than one freshly split piece.
What moisture level is considered seasoned firewood?
A commonly used target is 20% moisture content or less. Check your meter’s instructions and confirm that its displayed basis matches the guidance you are using.
Where should I place the meter pins?
Place them on a freshly split interior face, following the meter manufacturer’s directions. Do not use bark or rely on an unsplit log’s exterior.
Can I test firewood without splitting it?
An exterior reading may not represent the wet interior. Split a representative piece first, then test the fresh face.
How many pieces should I test?
Test several representative splits from different parts of the stack. Take at least three readings on each, as directed by the meter instructions.
Why do readings differ within one stack?
Pieces can differ in size, species, airflow, and exposure to precipitation. Test more pieces and keep wetter wood separate.
Does dry-looking bark mean wood is ready to burn?
No. Bark can look dry while the interior remains wet. Split the wood and test its newly exposed center.
Should I test end grain?
No. Use a fresh split face instead. End grain can give a misleading result for the interior surface used in the recommended test.
Do I need a species setting on the meter?
If the meter offers one, select the correct species as its manual directs. Also follow any temperature correction instructions.
How long does firewood need to season?
There is no dependable single time for every stack. Species, split size, airflow, and weather all affect drying, so retest the interior.
What should I do if readings are above 20%?
Continue seasoning the wood with airflow and top protection from precipitation. Retest later using fresh split faces.
(This article was written by one of our staff writers, Samuel Vance. Visit our Meet the Team page.)
