When you are about to buy wood fuel for your wood burner, pizza oven, outdoor chiminea, or a campfire, you should have one thing in mind - the optimum moisture content of wood for burning is below 20%. Two of the most popular options for firewood with less than 20% moisture content are well seasoned and kiln dried logs. Continue reading below, if you would like to find out more about seasoned vs kiln dried firewood, the pros and cons of each, and which is the better option for you.
Why Firewood Needs To Be Dry
Wood should be as dry as possible for burning, otherwise a lot of the heat in the stove of fireplace is used to evaporate the water from the wood. That means you produce less heat and more condensates and resins in the chimney. Condensates are the cause of chimney fires.
When buying firewood and logs, it is very important to ensure that the wood you buy has been properly dried: a lower moisture content means that your firewood will burn consistently well with little smoke, and will not blacken the glass of your stove door, and push out much more heat.
Green or “fresh cut” wood can have a moisture content of 50 percent or more, and will not burn efficiently. For the perfect burn, a moisture content of below 20% is recommended.
Is It Ok To Burn Wet Firewood?
Keep in mind that wood is a living thing, and as such, filled with water and nutrients when existing in a living tree. Wood from newly cut trees does not ignite well. Those who try to burn wet wood can damage the flu of their burners, create a lot of smoke and pollution, and will achieve minimal heat. This is damaging to the environment and to be avoided at all costs.
Seasoned vs Kiln Dried Firewood
But how do you get properly dried wood? The most popular options are buying seasoned firewood and in the last 5 years or so, going for kiln dried logs.
What is seasoned wood?
Seasoned wood is any firewood that has been left to dry on its own. In order for it to be seasoned well, it should be split into smaller logs shortly after cutting. Ideally, they should be cut into 25cm lengths and dried “ends out”. Splitting the wood into smaller pieces increases the surface area and also gives logs more of a chance to dry out.
During air drying, the logs are split then stored under cover, in a way that allows as much air as possible to flow around them so as to dry them as quickly as possible. The time it takes to season firewood differs depending on the type of wood: softer woods such as ash and pine will dry quickly (12-18 months), while those such as apple and oak that are denser will take longer (18-24 months) so as to be ready to burn.
The Pros of Seasoned Logs:
Seasoned firewood can be cut and dried yourself
If really well seasoned, users can achieve a heat output almost as good as kiln dried logs.
The Cons of Seasoned Logs:
Proper wood seasoning takes a long time (over 1-2 years).
If you buy green wood and season it yourself, you need space for seasoning and storing.
Seasoned wood usually only dries down to 25% moisture naturally. To get it lower than this requires open air drying in the summer months.
Because of the drying time, seasoned wood is often in short supply
What is kiln dried wood?
Kiln drying is a process of force drying in a commercial kiln, which can be done within anything from 4-6 days, depending on the efficiency of the kiln. Typically temperatures reaching 70°C are used in such kilns.
At the beginning of the kiln drying process, the pre-cut green wood is stacked into metal cages, and placed inside the kiln. The kiln, if you can imagine, is much like an oversized oven with an enormous fan for air circulation. Kilns differ in size and function but most of them will process big quantities of wood (as much as 100 pallets) at once. They drive the moisture out through repeated air flow and complex processes allowing any moisture in the firewood to escape.
Kiln dried logs are certain to perform well. Being thoroughly dry means they will light without problems, burn excellently, and provide high heat output. By burning cleanly, this means the stove glass should not go black or cause excess soot or tarring inside the flue. With kiln dried logs, you are still burning a completely natural product, they simply have less moisture meaning a much cleaner, hotter burn.
Kiln drying also kills insects during the process,so it is completely safe.
The Pros of Kiln Dried Logs:
The logs are ready to burn immediately.
Fryer wood means the logs create more heat and a much cleaner burn.
Kiln dried logs are sourced whenever needed, eliminating the need to store large amounts.
With the increase in online suppliers, kiln dried logs are always available.
The Cons of Kiln Dried Logs:
Delivery is on pallets most usually, so properties need access for a 7.5t truck minimum.
The cost can be as much as 10% more than commercially provided seasoned logs.
Seasoned vs Kiln Dried Firewood - Which One Is Better?
Kiln dried firewood will be dried right through, but air-dried logs can have varying water levels. Your kiln dried logs are guaranteed to burn and will be consistently dry. While the cost will be slightly higher than seasoned logs, you can be sure that your logs will light quickly and easily with kiln dried. With a low moisture content (less than 20 percent), your kiln dried wood can produce up to 30% more heat per kilogram, ultimately making the benefits economical.
Kiln dried firewood will be free of insects and mould. Wood that has been left outside for any length of time will attract critters, which will most certainly be noticed when setting up a fire. Kiln dried firewood is a cleaner alternative.
Lastly, your kiln dried wood is ready whenever you are. If you have left it late in the summer to buy logs you needn't be concerned – the kiln dried logs are instantly ready on delivery and require no treatment. When people run out of firewood in the middle of winter they are at risk of being sold firewood that has not been properly dried. With our high quality kiln dried product, customers can rest easy even when they get caught short at peak times.
In summary, resort to buying seasoned logs only if you have tested with a moisture meter that they are really dry and free of insects and mould.You should split the log open and test the content in the centre of the split log (insert the tester pins into the cut face). Often times wood can be drier on the outside than the centre, so testing moisture content from the outside (bark) of the log is an inaccurate method.
Seasoned or Kiln Dried Firewood FAQ
Now that we know what are the differences between seasoned and kiln dried logs, let’s answer some of your burning questions:
Q: What does seasoned firewood look like?
A: A good sign to look out for in well seasoned firewood is cracks in the end grain of the logs. To identify well seasoned/dried wood, check the ends of the logs. If they are brown in colour and slightly split at the ends, they will be dry. Dry wood is lighter in weight than wet wood and makes a hollow sound when hitting two pieces together. If there is any green shading visible or bark is hard to peel, the log is not properly yet dried.
Q: Why does wood spit in a fire?
A: The heat from the fire causes the fluids within wood to first boil and then vaporize into steam. The contained water begins to exert pressure in the log. Eventually, the wood gives way. The snap sound one hears is the wood splitting and releasing water into the flames. Kiln dried logs rarely spit.
Q: How long does it take freshly cut logs to dry before burning?
A: Green wood (that is, wood that has been freshly cut) can take over 1-2 years in the open air to season well enough for burning as fuel.
Q: How to store wood inside?
A: Storing your firewood inside can be very convenient. Before you haul your woodpile inside, make sure your wood is very well dried, find a good storage space and unit. Look out for bugs and don’t treat your wood with insecticide if you find them, as this may contaminate your fire and produce unwanted smells and gases. Bugs on kiln dried logs will already be dead and can just go in the fireplace with wood as normal.
We sell a large variety of high-quality kiln dried wood. Ordering kiln dried logs in crates is our most popular option. They are neatly stacked with premium logs and provide incredible value for money.
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