Think about how your firewood burns! Is it hard to light? Do you have an inconsistent smoldering flame? Does the fire produce lots of smoke? If you answered yes to all of these questions, then you probably have a moisture problem. So, what moisture level should firewood be?
Your firewood needs to have a low moisture content for it to burn efficiently. The optimal burn range is 10-15%, but anything under 20% should be fine. Wood gets too dry and burns hot once the moisture level drops below 8%.
All of those moisture readings are great to know, but what do they actually mean? Keep reading to learn find out how to take an accurate moisture reading. Don’t Worry! Taking a moisture reading is easier than you think.
What Moisture Level Should Firewood Be?
It doesn’t matter where/how you’re burning wood, most of your firewood woes can be solved by managing the woods moisture level. Excess water causes major problems when trying to make and maintain a fire. Ask yourself how the last couple of fires have burned and answer these basic questions.
- Was The Fire Hard To Light? Unless you live in Cleveland, you’ve probably never seen water light on fire. Freshly cut green firewood usually has a moisture level around the 45% range. It’s going to be hard to light a fire when almost half of a logs volume consists of water. You can do it, but it will take a lot of effort getting the wood down below 20% moisture. You might want to check out another one of my articles describing how I light a fire with wet wood.
- Did it burn consistently throughout the night? Wet wood will go from being flaming hot to a sputtering smoldering pile of hot garbage in a matter of minutes. There’s absolutely no consistency throughout the night. You would think that adding more wood would help, but that takes more heat away from the fire since most of the energy is used to dry out the wood.
- How much heat was it giving off? Wet firewood gives off very little heat since so much of the energy is used to get rid of excess moisture. That’s why it seems like smaller logs give off way more heat. It’s because smaller pieces of wood dry faster than larger logs in the same pile. You can use smaller pieces of firewood to get the temperature levels up if a good chunk of your firewood is wet.
- Are the logs smoldering and randomly losing their flame? There’s absolutely no consistency when dealing with green and wet wood. It burns at such a low temperature that the flame will constantly go out and the logs will smolder at a low temperature. You can usually perk the flames up a bit by improving airflow, but they go out minutes later.
- Do you have to deal with extreme levels of smoke? There’s no way to get rid of every last bit of smoke, but there shouldn’t be so much that your fires unenjoyable. Even smokeless firepits (these are awesome) produce some smoke as the wood burns off. Wet wood doesn’t let your fire get hot enough to complete the combustion process. You end up with black smoke as the lighter than air particulates lift up without completely burning off.
Moisture Level Of Freshly Cut Green Wood
There will be a lot of moisture in firewood that was recently cut and split. That’s why you have to go through the seasoning process to dry out your wood. It takes at least 6 months to drop the moisture level down low enough to burn.
After cutting down a tree, you can expect a moisture reading in the 40-50 percent moisture reading. It really depends on the type of wood and whether or not the woods rotting or soaking in water. Softer wood like pine, cedar and fir start out with a higher moisture reading.
It will quickly dry and catch up with the hardwoods if you follow the proper seasoning process. I’ll explain the fastest way to season your wood down below. Remember that you need to split firewood into smaller pieces for it to dry out.
Large Logs Take Forever To Season
Don’t expect large logs to dry out in a timely manner. It can take years for them to fully season due to their large diameter. The outside edges may dry out, but the middles remain wet at about 45% moisture level. They’re much more likely to rot and decay before getting close to burnable.
I recommend splitting logs into usable pieces soon after cutting down a tree. That’s the only way to initiate the seasoning and drying process. Plus green, freshly cut firewood, is easier to split. You will probably finish faster and there will be less work on your log-splitter.
Aim For The 10-15 Percent Range (Under 20 Burns Well)
Try to get your moisture level down below the 20 percent range for easier fires. That’s the point where firewood gets easy to light and puts off much less smoke. Generally speaking, the fires will burn much better than they did with wet wood.
Don’t stop the drying process there! Fires really start to burn once moisture levels drop down into the 10-15 percent range. That’s where you reach the optimal burn range. You will almost zero smoke, fires will burn extremely hot, there will be little ash, and the logs still last a long time.
This is the sweet spot that should happen right around the 2 year seasoning mark. It’s where you want to start burning the majority of your wood. I like to cycle my firewood so there’s always 2-3 year old wood to burn. That’s easier said than done since it can be hard to estimate .
Can Firewood Be Too Dry?
Firewood can get to the point that it’s a little bit too dry, but that’s rare. Wood starts to burn way too hot once it gets below an 8% moisture level. It still lights easy, but you’ll burn through the wood much faster than you’d like. Plus some hardwoods have been known to burn holes through the bottom of wood stoves.
Keep in mind, that it’s very rare for firewood to get too dry. You need to pair perfect storage conditions with a very low humidity environment. That’s not going to be possible throughout most of the country and people rarely heat their homes with firewood in places where that is possible (Arizona, Nevada, etc).
Wood that’s been sitting around for a while will typically bottom out at the 10% mark. That’s still in the optimal range, but a little bit lower than I like. You will still have great fires! They’ll be really easy to light, produce little smoke, and burn evenly.
Using a Moisture Meter
I highly recommend picking up a moisture meter if you don’t already have one. You’re not performing surgery here, so you don’t need that good of a meter. Pick one up at your local hardware store or pick out the cheapest meter you can find on Amazon.
A moisture meter is a cheap handheld device that can be used to measure the moisture content of wood. It uses an electromagnetic signal to measure the resistance throughout the wood. Water is an excellent conductor so higher resistance means less overall moisture.
There are 2 different styles of meters. They both use the same basic testing method. You have a pinned meter that has pins that puncture the wood and pin-less that measures the outside surface. They both have their benefits, but I’d go with a pinned meter. The seasoning process dries wood from the outside in so you want to get a reading from the inside of your log instead of the surface.
Both meter styles work basically the same way. With a pinless meter you hold it against the wood, and a pinned meter would be pushed into the wood. Press the start button and it will give you a moisture reading. Some of the more advanced meters make you input the species of wood, but it’s usually choose between hardwood/softwood.
How To Measure With a Moisture Meter
A moisture meter is surprisingly simple to use. Follow a few basic instructions and you’ll have very accurate readings. I’ll give you a few tips to check moisture content without a meter if you continue into the following section below.
- Remove the end cap of your moisture to reveal the pins (only applies to a pinned meter). With the cover removed the pins will be used to measure the moisture content. The device will send an electromagnetic charge through the wood to determine the resistance level.
- Turn on your meter using the power button and wait for the meter to zero out so it’s ready to take a reading.
- Gently push the 2 pins a few millimeters into the wood or place the pinless meter up next to the wood. Both of the pins need to be touching/embedded into the wood for the meter to provide a reading. It’s taking an electromagnetic reading between the two pins. The prongs should run along the grain parallel with the wood when testing.
- The moisture meter will normally give you a reading immediately, but you may need to press a start button to pulse the electrodes. You might want to repeat the process on a few different pieces of wood to get the overall moisture content of your wood pile. Wood that’s higher up the pile and centered will usually have an increased moisture reading.
- The meter will give you a reading on the screen that tells the moisture level in the wood. If you get back an error reading that usually means one of the pins isn’t touching the wood. Either get both pins on the wood or tighten them up because there could be a loose connection.
Generally speaking, wood will burn better at a lower moisture level. Any reading below 20% will make a very good fire. You can burn wet wood over 20%, but it’s going to be an inconsistent burn. Your fires will be hard to light, inconsistent, and produce lots of smoke.
Visual Difference Between Wet and Dry Firewood
Dry firewood that’s ready to burn will look and feel different than freshly cut green wood. Use a quick visual inspection if you don’t have access to a moisture meter. You’ll be looking at the color, weight, bark and texture of the wood.
As wood dries it goes through the natural degradation process. It goes from a vibrant color with a greenish tent, to a grayish/white, all the way to a brown when it’s old and dry. There’s a very obvious difference between the colors. Just keep in mind that just because wood is gray/brown doesn’t mean it’s dry. That just shows signs of aging, but it could be wet if the wood wasn’t properly stacked/covered.
Look for more subtle signs of moisture leaving the wood. The wood will feel lighter, get a rough/ragged texture, bark will peel, and cracks will form along the length of your logs. That’s a natural process as the water leaves the wood.
How Long Does The Seasoning Process Take and Can I Speed It Up?
The seasoning process usually takes between 6-12 months to get your wood dry enough to efficiently burn. It can take longer if you’re wood isn’t properly stacked and covered.
How long the seasoning process takes is largely dependent on the time of year you split the firewood. Wood that’s cut/split in the spring will normally be ready to burn by the winter. Firewood that’s split in the fall may not be done until the following winter 1 year later since you need at least 4-6 months of summer sun to dry the wood.
How can I speed up the seasoning process? You can speed up the seasoning process by learning the right way to stack your firewood. Make sure your firewood is up off the ground, covered on top, sides should be exposed to increase airflow, and try to maximize sunlight. If you can follow those steps your wood should be dry/seasoned within 6 months of sunshine (assuming it’s split wood).
Build/buy a rack to get your wood up off the ground. It can be as simple as stacking and covering your wood on pallets, but I like to build a nice rack out of pressure treated lumber. I recently switched over to using firewood rack brackets (these ones). They make building a rack so much easier. It takes less than 5 minutes and you can swap out boards every 5-10 years when they start to look bad.
Most people cover up their wood using a cheap 6×8 tarp. Just make sure the sides of your wood pile are exposed to increase airflow through the pile. Most of my piles are covered with tarps, but I use a REDCAMP firewood cover on the pile that I access everyday. Being able to quickly unzip the cover is so much easier than messing around with a tarp and straps.
Watch Out For Commercially “Seasoned” Wood
Most wood that’s sold to consumers as “seasoned” isn’t ready to be burned. There’s no regulatory body that determines whether or not wood is seasoned so companies can claim whatever they want. They’ll sell wood that’s over a 40% moisture level and claim that it’s seasoned.
A research study found that the average moisture content of commercially sold firewood was 66 percent. That’s only slightly less than green wood and far higher than the recommended level. Properly seasoned firewood should have a moisture content under 20%.