Maintenance procedure · Written to ASD-STE100 Issue 9 · Formatted to ANSI Z535

Measure firewood moisture content

Use a pin moisture meter to test for 20 percent or less
ApplicabilityThis procedure applies to anyone who burns firewood in a fireplace, wood stove, or heating appliance and wants to verify that the wood is dry enough to burn safely and efficiently.
Task time8 min editorial estimate
PersonnelOne
Revisionv1 · 2026-08-03
BEFORE YOU BEGIN

Before you begin. This procedure is general reference information, not professional advice. Equipment varies by manufacturer, model, and year. Always follow the documentation supplied with your equipment — where it differs from this page, follow the manufacturer. Verify that you have the tools, the working conditions, and the ability to do this task safely. If anything is unclear, if the equipment is damaged, or if the task exceeds your experience, stop and use a qualified professional. You are responsible for your own safety and for the outcome. This site accepts no liability for any loss, damage, or injury arising from the use of this information.

Specifications marked unverified could not be traced to a manufacturer source. Do not rely on them — obtain the value from your equipment documentation.

Summary

A pin moisture meter measures the water content inside firewood by detecting electrical resistance. Wood that has been properly seasoned (dried) contains 20 percent moisture or less and burns efficiently without producing excess creosote. This procedure explains how to select the correct location on a firewood piece, insert the meter pins, read the measurement, and apply a species correction if your meter does not do it automatically.

Necessary equipment

ItemNote
pin moisture meterMEASURE WITH A PIN MOISTURE METER FOR WOOD. CHOOSE A METER CALIBRATED FOR WOOD MEASUREMENT.
firewood materialSELECT A PIECE THAT IS LARGE ENOUGH TO ALLOW YOU TO INSERT THE METER PINS SAFELY.
hatchet or splitting tool (optional) materialUSE A HATCHET OR AXE TO EXPOSE A FRESH SURFACE IF THE FIREWOOD IS NOT ALREADY SPLIT.

Specifications

target moisture content
Manufacturer or standard verified
20 percent

Source: Best Wood-Burning Practices · tier 1 · accessed 2026-08-03

Procedure

Estimated 8 min

  1. SELECT A PIECE OF FIREWOOD.
    <1mReport a problem with step 1, Procedure
  2. SPLIT THE WOOD LENGTHWISE OR EXPOSE A FRESH SURFACE WITH A HATCHET.
    1mReport a problem with step 2, Procedure
  3. INSERT THE METER PINS AS THE MANUAL FOR YOUR METER SHOWS.
    • Pin direction changes the reading.
    • Obey the pin direction in the instructions for your meter.
    • Split the log first and measure the new inner face.
    <1mReport a problem with step 3, Procedure
  4. READ THE MOISTURE PERCENTAGE ON THE METER DISPLAY.
    <1mReport a problem with step 4, Procedure
  5. IF THE METER DOES NOT APPLY CORRECTION AUTOMATICALLY, CHECK THE INSTRUCTION MANUAL.
    1mReport a problem with step 5, Procedure
  6. FIND THE CORRECTION FACTOR FOR YOUR WOOD SPECIES IN THE MANUAL TABLE.
    2mReport a problem with step 6, Procedure
  7. IF NEEDED, APPLY THE CORRECTION FACTOR TO YOUR MOISTURE READING.
    1mReport a problem with step 7, Procedure
WARNING

DO NOT BURN WOOD ABOVE 20 PERCENT MOISTURE CONTENT.
Wood at this moisture level produces excess creosote. Creosote accumulates in the chimney and can ignite.

  1. COMPARE THE CORRECTED MOISTURE READING TO 20 PERCENT.
    <1mReport a problem with step 8, Procedure
  2. RECORD THE MOISTURE MEASUREMENT AND THE WOOD SPECIES.
    1mReport a problem with step 9, Procedure

Terminology

This page uses one term for each item and holds it throughout, as ASD-STE100 requires. Equipment sellers and other guides use the names below for the same parts.

pin moisture meter
Also called: no common alternatives
seasoned wood
Also called: no common alternatives
moisture content
Also called: no common alternatives
creosote
Also called: no common alternatives

When to use a professional

IF YOUR FIREWOOD MEASURES ABOVE 20 PERCENT MOISTURE CONTENT, SEASON THE WOOD OUTDOORS FOR ADDITIONAL MONTHS BEFORE USE. IF A CHIMNEY FIRE OCCURS, STOP, LEAVE THE BUILDING, AND CALL LOCAL FIRE SERVICES.

Common questions

What is the difference between a freshly split surface and a weathered surface?

A freshly exposed interior surface shows the true moisture content of the wood. A weathered or exposed surface has been drying in air and rain, so it reads artificially low — sometimes 4 to 8 percent lower than the wood's actual interior moisture. Always split the wood or expose a new face immediately before measuring.

Do all moisture meters measure the same way?

Most pin moisture meters are calibrated to Douglas fir as a baseline. When measuring hardwoods like oak or maple, the meter displays a reading 2 to 4 percent lower than the wood's actual moisture content. Check your meter's instruction manual to see whether it applies automatic species correction or requires manual adjustment.

What happens if I burn wood above 20 percent moisture?

Wet wood burns poorly, produces excess smoke, and deposits creosote inside the chimney. Creosote is a combustible residue and it can ignite. We are not going to tell you what share of chimney fires it causes, because the number we would have to quote is not in any source we hold. What EPA does publish is that three of every ten house fires caused by home heating come from poorly maintained fireplaces and dirty chimneys. Burn dry wood and have the chimney swept.

How long does firewood take to dry to 20 percent?

The EPA recommends seasoning firewood for at least six months. The actual time depends on the wood species, piece size, and outdoor storage conditions. Softwoods like pine dry faster than hardwoods like oak. Store wood off the ground with only the top covered — covering the sides traps moisture.

Can I measure bark or the outside of the log?

No. The bark and weathered exterior do not represent the interior moisture content of the wood. Always split the wood or expose a fresh surface immediately before inserting the meter pins.

No related procedure is published yet. This section fills as the repository grows.

Sources

Every specification on this page is traced to one of these sources. Tier 1 is a manufacturer document, a published standard, or a government safety authority. See Standards for the full tiering rule.

  1. Tier 1Burn Wise: Test Your Wood with a Moisture MeterU.S. Environmental Protection Agency, Burn Wise Program · accessed 2026-08-03 · re-verification due 2027-01-30
  2. Tier 1Best Wood-Burning PracticesU.S. Environmental Protection Agency, Burn Wise Program · accessed 2026-08-03 · re-verification due 2027-01-30
  3. Tier 1Burn Wise: Facts & Figures + Health and Safety TipsU.S. Environmental Protection Agency, Burn Wise Program · accessed 2026-08-03 · re-verification due 2027-01-30
  4. Tier 1Method 28 - Certification and Auditing of Wood Heaters (40 CFR Part 60, Appendix A-7)U.S. Environmental Protection Agency · accessed 2026-08-03 · re-verification due 2027-01-30

Revision history

Current version 1 · updated 2026-08-03 · next review due 2027-08-03

  1. v1 · 2026-08-03First publication.

Corrections to this page are listed in the public corrections log. Reports that are credible and not yet verified are listed in the public errata register, and an open one renders above the step it concerns.

Comments and corrections

Found an error? A correction with a manufacturer source is applied and logged publicly. You can also write to corrections@fixchecklist.com.

Every step above carries its own report control, which tags the report with that step so a correction reaches the right place. For anything about the procedure as a whole — the order of the sections, a step that is missing, something that did not match your equipment — use this: report something about this whole procedure.

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