Wood-burning stoves have soared in popularity in recent years, as people are not only becoming more aware of the environmental benefits that come with using an Ecodesign stove, but there is a growing desire to be less reliant on the grid for heating.
If you burn wood, it is crucial to be aware of what you are burning and the dangers of burning unseasoned wood.
What Is Unseasoned Wood?
Unseasoned wood refers to firewood that hasn’t been properly dried or cured. Freshly cut wood, also known as green or wet wood, has a high moisture content, often as much as 50-60%, depending on the type of wood. When wood is seasoned, it is allowed to dry out over time, typically for 6-12 months, which reduces its moisture content to around 20% or less. Some hardwoodslike oak, can take upwards of two years to season. An alternative to seasoning wood is having it kiln-dried.
Ready to Burn – If you’re buying logs in quantities of less than 2 m3, they must be certified as Ready to Burn (have a moisture content below 20%). Learn more about this scheme here.
Moisture Content of Wood by Type (in Freshly Cut or Green Wood)
Oak (Red and White) – 40-60%
Oak is dense and heavy, with high moisture content when freshly cut. It is one of the most popular hardwoods for firewood, but it takes longer to season.
Ash – 50-60%
Ash burns well when properly seasoned and has a similar moisture content to oak when freshly cut. It is easier to split and dries relatively quickly.
Beech – 50-60%
Beech is another hardwood that retains a high moisture content when freshly cut. It is known for producing good heat output once seasoned.
Maple (Sugar, Red) – 45-55%
Maple has a high moisture content when fresh and, like ash, can dry out faster than oak. Once seasoned, it burns cleanly and provides good heat.
Birch – 45-55%
Birch wood has a high moisture content when fresh, but it dries faster than many other hardwoods. It burns quickly and produces a decent amount of heat.
Pine (Eastern White, Red Pine) – 40-50%
Softwoods like pine have a slightly lower moisture content when freshly cut compared to hardwoods. However, they still require seasoning to burn efficiently.
Douglas Fir – 45-55%
Douglas Fir is a softwood with moderate moisture content when fresh. It is commonly used for firewood in the Pacific Northwest but requires proper seasoning for optimal burning.
Spruce (Norway, Sitka, Black Spruce) – 40-50%
Spruce is another softwood with a relatively high moisture content when fresh. It burns quickly, so seasoning is important to improve efficiency.
Fir (White Fir, Balsam Fir) – 40-50%
Like spruce, fir has a high moisture content when freshly cut. It burns hot but fast, and proper seasoning is necessary to avoid excessive smoke and creosote buildup.
Cherry (Sweet, Black) – 50-60%
Cherry wood is a dense hardwood with a high moisture content when fresh. However, it dries relatively quickly and burns with a pleasant aroma once seasoned.
What Happens When You Burn Unseasoned Wood?
Lower Efficiency and Less Heat
One of the most immediate risks of burning unseasoned wood is a decrease in efficiency. As unseasoned wood has a high moisture content, much of the energy produced by the fire goes into evaporating the water in the wood rather than creating heat. This means that less energy is available to heat your room, and you may find yourself needing to burn more wood to achieve the same amount of warmth. Essentially, you’re wasting energy and money when burning unseasoned wood.
More Smoke and Pollution
Unseasoned wood produces significantly more smoke than seasoned wood. The high moisture content leads to incomplete combustion, which results in excess smoke being emitted into the air. This not only makes the air around your stove smell but also contributes to air pollution. Smoke contains harmful pollutants, including carbon monoxide, particulate matter, and volatile organic compounds (VOCs), which can be dangerous to both health and the environment.
Creosote Buildup
Burning unseasoned wood increases the amount of creosote buildup in your stove’s flue and chimney. Creosote is a highly flammable substance that forms when wood is burned incompletely. It sticks to the inside of the chimney and flue, and over time, it can accumulate and create a dangerous fire hazard. If creosote buildup is left unchecked, it can lead to a chimney fire, which can cause severe damage to your home or even result in a total loss. Regular chimney inspections and cleanings are essential, but reducing creosote buildup starts with burning properly seasoned wood.
Soot and Residue in the Stove
Burning unseasoned wood can lead to more soot and residue building up inside your stove. This can cause the stove to become congested more quickly. A congested stove will not burn as efficiently, leading to more frequent cleaning and maintenance being required. Additionally, the excess soot can negatively impact the stove’s lifespan.
Increased Wear on the Stove and Chimney
The byproducts of burning unseasoned wood, excess moisture, creosote, and soot, can also cause long-term wear on your stove and chimney system. Over time, the moisture from the unseasoned wood can cause rust or corrosion, which can damage the stove’s components and reduce its efficiency. The longer this is allowed to continue, the more likely it is that costly repairs will be needed.
Difficult to Start and Maintain a Fire
Unseasoned wood is harder to ignite and sustain than seasoned wood. The high moisture content in unseasoned wood makes it more difficult to get a fire started, and once the fire is going, it tends to burn at a lower temperature. This can make it challenging to maintain a steady flame, requiring more effort to keep the fire alive. In some cases, you may need to add more fuel frequently, contributing to inefficiency.
Why You Should Always Use Seasoned Wood
Better Heating Efficiency: Properly seasoned wood burns hotter and more efficiently, providing more heat with less fuel. This allows you to keep your home warm without burning through piles of wood.
Cleaner Burns: Seasoned wood produces less smoke, less soot, and fewer harmful emissions. This is better for both the environment and your health.
Less Creosote and Maintenance: Using seasoned wood greatly reduces the amount of creosote buildup in your chimney, decreasing the need for regular cleaning and reducing the risk of dangerous chimney fires.
Longer Stove Lifespan: Proper wood maintenance, such as burning seasoned wood, helps preserve the life of your stove and chimney by reducing the wear and tear caused by moisture and corrosive substances.
How to Tell if Wood Is Seasoned
The simplest way to check if wood is properly seasoned is by looking for visual and tactile cues:
Colour: Seasoned wood tends to be darker and more cracked than unseasoned wood.
Sound: When you knock two pieces of seasoned wood together, it should produce a sharp, hollow sound, while unseasoned wood will make a dull thud.
Weight: Seasoned wood is significantly lighter than unseasoned wood, as the moisture has evaporated.
Cracks: Look for visible cracks on the ends of the logs—this indicates that the wood has dried properly.
Moisture Meter: If you have one, you can use a moisture meter to check the wood’s moisture content.
While it may be tempting to burn freshly cut wood to avoid waiting for seasoning, the drawbacks of burning unseasoned wood far outweigh the benefits. Not only does it result in inefficiency, excessive smoke, and creosote buildup, but it can also damage your stove and chimney.
Read more related articles here:
Selecting a moisture meter
How is wood kiln-dried
Best wood to burn on a stove
