When it comes to getting the best from your fire, firewood moisture content is more important than many realise.
Whether you're using a wood burning stove, open fire, chimenea or fire pit, the dryness of your logs directly impacts heat output, efficiency, smoke levels and even the long-term health of your chimney.
In this guide, we’ll break down exactly what firewood moisture content means, why it matters, and how to make sure you're correctly checking firewood moisture content and burning the right logs every time.
What is Firewood Moisture Content?
Firewood moisture content refers to the amount of water still present inside wood, expressed as a percentage. This moisture percentage is key to understanding firewood quality.
Freshly cut (green) wood can contain 50-60% moisture, making it completely unsuitable for burning until it has been properly dried.
Before wood can burn efficiently, that moisture needs to be reduced significantly, otherwise, much of the fire’s energy is wasted evaporating water rather than producing heat.
What Moisture Should Firewood Be?
For efficient burning, firewood should have a moisture content for firewood below 20% before you use it.
This is the recognised UK standard for clean burning fuel and is backed by the Woodsure “Ready to Burn” scheme.
Using firewood below this level will:
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Produce less smoke
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Burn hotter and more efficiently
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Reduce soot and chimney build-up
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Improve overall fire performance
At Calido, all of our kiln dried logs are carefully dried to consistently fall below this level, giving you a cleaner, hotter and more reliable burn without the guesswork.
Why Firewood Moisture Content Matters
Heat Output
Wet wood uses energy to evaporate water before it can produce heat. This means less usable warmth from every log you burn.
Smoke & Air Quality
Higher moisture levels lead to more smoke and emissions, which is not only unpleasant but also less environmentally friendly.
Chimney Health
Burning damp logs increases creosote build-up inside your flue, which can lead to blockages and increased fire risk over time.
Efficiency
You’ll burn more logs to achieve the same level of heat, making wet firewood a false economy.
Kiln Dried vs Seasoned Firewood
Understanding the difference between kiln dried and seasoned firewood is key to choosing the right fuel.
Kiln Dried Firewood
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Dried in controlled kiln environments
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Consistently below 20% moisture content
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Ready to burn immediately
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Clean, efficient and reliable for wood burners and wood burning stoves
Seasoned Firewood
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Air dried over time
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Moisture levels can vary significantly
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Performance depends on storage conditions
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Less predictable
If you want consistent performance without needing to check firewood moisture content using a tool every time, kiln dried firewood is the most straightforward and reliable option.
How to Tell if Firewood is Dry
Use a Moisture Meter
The most accurate method is to split a log and test the centre using a moisture meter. Readings should be below 20% moisture content.
You can purchase these for around £20 at your local DIY store or order a meter online.
Look for Visual Signs
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Cracks in the ends of logs
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Lighter weight
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Bark beginning to peel away
Sound Test
Dry logs make a sharp “clack” when knocked together, while wet wood produces a dull sound.
Burn Test
Dry logs ignite easily and burn with a steady flame and minimal smoke, ideal for efficient burning in any wood burner or wood burning stove.
Why Wet Firewood Causes Problems
Burning wet firewood doesn’t just mean less heat and more smoke - over time, it can lead to more serious performance and safety issues.
When logs contain too much moisture, much of the fire’s energy is used to evaporate water rather than produce heat. This results in a less efficient burn and a poorer overall experience.
Common issues include:
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Poor heat output
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Excess smoke and emissions
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Blackened stove glass
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Increased chimney and flue maintenance
Over time, burning wet wood can also lead to a build-up of creosote inside your chimney, increasing the risk of blockages and potential chimney fires.
How to Store Firewood Properly
If you’ve purchased firewood with below 20% moisture content, it’s important to store it correctly to maintain its quality.
We recommend that when you purchase kiln dried logs, you should:
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Keep logs off the ground
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Store in a well-ventilated area
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Protect from rain while allowing airflow
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Avoid sealing logs in airtight spaces
If you burn regularly and are buying in bulk, a log store is a worthwhile investment to keep your firewood in the best possible condition.
Do You Need a Moisture Meter?
While not essential, a moisture meter can be useful if you regularly store or source your own wood, helping you correctly check firewood moisture content quickly.
However, choosing kiln dried logs from a trusted supplier like Calido removes the need for testing entirely.
Choosing the Right Firewood
At Calido, we supply premium hardwood firewood, including Birch, Ash and Oak - each with slightly different burning characteristics, making them better suited to different firewood needs.
For example, if you’re lighting your fire little and often, you may prefer a log that lights quickly and gives off fast heat. If you’re burning for longer periods, a denser hardwood that provides a longer, steadier burn may be more suitable.
Whichever you choose, there are a few key things to look for when selecting firewood:
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Firewood moisture content below 20% for clean, efficient burning
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Hardwood species such as birch, ash or oak
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Consistent log sizing for an even, controlled burn
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A reliable supplier to ensure consistent quality
All of our kiln dried logs are carefully selected and dried to meet these standards, giving you confidence that every delivery is ready to burn and perform as expected.
Moisture content is one of the biggest factors affecting how well your fire performs.
By choosing properly dried logs, you’ll enjoy better heat, cleaner burning and a more efficient fire overall.
If you want a simple, reliable solution, kiln dried firewood offers consistency and convenience every time.
Frequently Asked Questions
What moisture content should firewood be?
Firewood should have a moisture content below 20% for efficient and clean burning.
Is kiln dried firewood better than seasoned?
Yes, kiln dried firewood is more consistent, burns cleaner and is ready to use immediately.
Top tip: Look out for the Woodsure Ready to Burn scheme logo for reassurance that your firewood meets UK standards.
How can I tell if my firewood is dry?
You can use a moisture meter as a quick way to tell. Otherwise, checking firewood moisture content can be done quickly by checking for cracks, picking up your logs to feel if they are light, and listening for a sharp sound when the logs are knocked together.
