Across Europe and North America, more households are opting for wood stoves and fireplaces as a way to reduce their energy costs. While dry firewood is crucial for clean, efficient heating, many homeowners don’t realize their logs are still damp until the fire struggles to burn and the stove glass becomes sooty. A simple household item, like washing-up liquid, can help prevent this disappointment.
Understanding the Importance of Dry Firewood
Burning wet firewood isn’t just inconvenient; it has significant consequences for your finances, your stove, and the air quality in your home. Properly seasoned firewood should have a moisture content below 20%. Anything higher results in wasted energy as water in the wood evaporates instead of providing heat. When wood is improperly seasoned, several issues arise:
- Difficulty lighting the fire and slow ignition.
- Sticky deposits forming on the stove glass and flue.
- Increased smoke and fine particles both indoors and outdoors.
These issues can lead to chimney fires, higher maintenance costs, and more frequent cleaning. In some regions, burning damp wood is restricted due to its negative impact on air quality. Checking your firewood before the heating season is not just a trivial task—it affects comfort, safety, and overall running costs.
How to Identify Dry Firewood
Knowing what dry firewood looks, feels, and sounds like can help you make an informed decision. Seasoned wood typically shows the following signs:
- Cracks at the cut ends and bark that peels off easily or has already fallen off.
- A slightly dull or greyish color compared to freshly cut wood.
- A lack of mold or soft, spongy spots—if present, the wood was likely stored too damp, pointing to poor storage and reduced heating value.
When you handle firewood, it should feel lighter than expected, with a faint woody scent rather than a strong, resinous odor. Comparing two similar pieces will help; if one feels heavier and smells “green,” it likely has more moisture content than the lighter, drier one.
Sound and Smell: Quick Tests for Dryness
Using sound and smell to evaluate firewood is an old but effective method. Here’s how you can do it:
- Knock two logs together. A dry log produces a clear “clack” sound, while a damp one will emit a dull thud.
- Freshly cut wood gives off a strong sap or resin scent. Once seasoned, this smell fades, leaving only a mild woody aroma.
These simple tests help determine if your firewood is ready for use. If a log sounds dull or still smells green, it’s likely too moist for burning.
The Washing-Up Liquid Test: A Simple Trick
One surprisingly effective method to check the dryness of your firewood is the washing-up liquid bubble test. Here’s how it works:
- Take a straight-grained, non-rotten log and apply a small amount of washing-up liquid to one sawn end.
- Spread the liquid around to create a thin film.
- Blow into the other sawn end of the log.
If the wood is sufficiently dry, you’ll see bubbles form at the soapy end. If no bubbles appear, the wood is likely still damp at the core, even if the outside appears dry.
Using a Moisture Meter for Precision
If you frequently buy large amounts of firewood, a moisture meter can provide a more accurate assessment of dryness. These devices are easy to use and give clear readings. Simply push the probes into the freshly split ends of the logs to get a moisture reading. Aim for a moisture content of less than 20% before burning. While moisture meters have a small upfront cost, they offer reliable, repeatable results, unlike visual checks or sound tests, which can sometimes be misleading.
Best Practices for Storing Firewood
Proper storage is key to ensuring your firewood dries out effectively. Air movement is crucial for seasoning, so stack your wood outdoors, ideally under a roof with open sides for ventilation. Make sure the wood is raised off the ground to prevent moisture absorption and leave small gaps between logs to allow airflow. Avoid storing firewood in closed spaces like garages or sheds, as they often trap moisture rather than promote drying.
How Long Does Firewood Need to Dry?
The drying time for firewood depends on several factors, including the wood’s species, climate, and how it’s cut. As a general guideline:
- Softwoods (pine, spruce, fir) need about 6–12 months.
- Medium hardwoods (birch, poplar) require 12–18 months.
- Dense hardwoods (oak, beech) take 18–24 months or longer.
To speed up the process, split the logs early. Larger rounds can retain moisture inside even after two years. Combining visual checks, the sound test, and a moisture meter will help you gauge whether the wood is dry enough for burning.
What Does “Moisture Content” Really Mean?
Moisture content refers to the proportion of water in the wood relative to its dry mass. Freshly felled logs can contain up to 50% moisture. As the wood dries, the moisture percentage decreases, making the wood lighter and more energy-efficient for burning. Ideally, you want firewood with a moisture content of around 20%. This ensures cleaner combustion, less soot buildup, and greater heat efficiency.
Winter Scenario: Testing Firewood
Imagine a family who ordered firewood for the winter, but when they check it in October, some of the logs are still damp. After inspecting and testing with sound and bubbles, they discover that many logs still have too much moisture, reading as high as 28% on a moisture meter. By separating the dry logs with a moisture content of 18–20%, they ensure they start the heating season with firewood that burns efficiently.
Environmental and Health Benefits of Dry Wood
Using dry firewood doesn’t just improve comfort—it also reduces harmful emissions that affect air quality. Burning wet wood releases more fine particles and unburned hydrocarbons, which are linked to respiratory issues. Properly seasoned wood helps maintain cleaner stove flues, reducing the amount of tar buildup that can lead to dangerous chimney fires.
By spending a few minutes checking your logs, you can avoid the frustration of smoky, inefficient fires. Whether using basic visual checks, the washing-up liquid trick, or investing in a moisture meter, it’s worth making sure your firewood is ready for winter.
