A tree that is freshly cut down contains a significant amount of moisture. It is considered green or unseasoned because of this high level of water inside the wood.
The moisture content of any type of wood can be measured by weighing the wood when it is green and comparing it to the weight of this same wood when it is completely dried to 0% moisture.
For example, if a green piece of maple weighs 75 grams when green and 50 grams when it reaches 0% moisture, its moisture content would be 50% as calculated here (75-50)/50 = 50%.
The various types of wood used for firewood will have different percentages of moisture content. Seasoning time will vary based on the type of wood.
Measuring Firewood Moisture
We recommend buying a moisture meter that will help take the guessing out of when your firewood is seasoned.
The General Tools MMD4E Digital Moisture Meter found on Amazon is a popular meter that can be used for this purpose.
You simple stick the two pins on the meter into the firewood and a digital readout will tell you if the wood has low, medium, or high moisture. Additionally, it will provide the percentage of moisture in the wood. Firewood with approximately 20 percent or less moisture content is ready for burning.
You can see how efficiently this meter works in the below video. Be sure to check the inside of firewood and not just the ends as shown in the video if you plan on using this meter. The inside may indicate higher moisture content.
Given the relatively inexpensive price of this meter, it is a tool that will likely provide many readers a lot of value for years to come.
- DETECT MOISTURE- Determine the moisture content of wood and other building materials (like drywall) or check water damaged areas to see if moisture is still present
- FIRST STEP IN MOLD PREVENTION - By checking suspicious water stains with a moisture tester around the house, you can determine whether the area is wet (a perfect breeding ground for mold) or has long since dried
- ACCURACY- Stick the stainless steel pins into the surface of what you are measuring in order to get a read-out. Overall measurement range of 5 to 50% for wood and 1.5 to 33% for building materials as well as low, medium and high moisture tones and colored green, yellow and red LED visual alerts
- EASY TO READ AND USE- Large 0.3 in. (8mm) high digits in a backlit LCD display for quick and easy viewing plus a hold function to freeze a reading, auto power off and a low battery indicator
- INCLUDES- Extra 0.3 in. (8mm) stainless steel pins, protective cap that doubles as a calibration checker and a “9V” battery
How Long Does It Take To Season Firewood?
The length of time it takes to season firewood will vary based on the wood as previously stated. If you want to bypass the moisture meter recommended above, you can use an estimate for when it will be seasoned.
Generally, split and appropriately stacked firewood will take approximately six to eight months to season. It should be stacked off the ground and preferably in a firewood cart or rack.
Air circulation should be allowed from all sides; therefore, do not stack the wood directly against a fence or wall. Leave the seasoning firewood outside as opposed to in the garage, shed, or basement.
Please read our article titled Can you store firewood in the garage? for more information on why it best to season firewood outdoors.
Keep in mind that firewood tends to get darker as it ages. If you have the same species of wood in a pile and some logs are dark than others, the darker pieces may be an indication of more seasoned wood.
Additionally, cracking on the edges also may be a sign that the wood is ready to be burned.
Finally, the sound of two pieces of seasoned wood hit together will sound different than unseasoned wood. The video below from BostonFirewood.com provides an excellent example of this sound difference.
Why Burn Only Seasoned Firewood?
Many people question, why even season firewood in the first place? Outside of unseasoned firewood being difficult to ignite, there are some other problems that arise from burning green wood.
The first issue is the lack of heat production. When burning unseasoned firewood, a lot of energy is used to burn away the moisture. This energy use takes away from the production of heat creating mediocre warmth from the fire.
Another problem is that the moisture in unseasoned firewood produces an excessive amount of smoke. This high concentration of smoke allows creosote to form.
Creosote produces black deposits that are particularly harmful when they harden and build up inside a chimney. As Doctor Flue indicates, the primary concerns with creosote are skin/eye irritation, respiratory issues, and cancer. Furthermore, creosote is also a leading cause of chimney fires due to being flammable and able to produce an extremely high temperature inside the chimney.
It is best to have a professional chimney sweep remove the build up of creosote if you suspect it to be a problem in your home. You likely do not want to risk your health or potentially not adequately removing it on your own.
If you have a lot of firewood, do yourself a favor and purchase a moisture meter. It will tell you exactly when your firewood is seasoned and is simple to use. For the price, it is an excellent investment to ensure you are not burning green wood.
When you only have a small stack of firewood that you plan on burning, a moisture meter is potentially overkill. Season the stack for several months and use your best estimate of when it is seasoned. Burning a test piece of firewood will provide a good indication of how well its seasoning