Firewood is too wet to burn efficiently if its moisture content exceeds 20%. You can spot wet wood by looking for dark, uncracked ends and checking for a dull "thud" when tapping two logs together. For a precise test, use a Wood Moisture Meter to measure the inside of a freshly split log.
To quickly tell if wood is dry enough to burn, check for a moisture content below 20% using a Wood Moisture Meter. Alternatively, knock two pieces together—dry wood makes a hollow, resonant sound, while wet wood makes a dull "thud".
Yes, you can burn wet or green wood in emergency situations, but it is highly inefficient and not recommended. Burning dry, seasoned wood with a moisture content under 20% is the most effective way to produce heat.
It's important to burn only wood with moisture content below 20%. Burning wood with higher moisture content creates more smoke, which contains harmful chemicals and particulates and forms creosote on your chimney. It also gives you less heat, because it takes energy to boil off the excess water.
A smoldering fire is another sign you are burning wet wood. Dirty or cloudy looking glass doors, and smoke coming from the chimney, are also indicators that either the fire needs more air or your wood is too moist, which creates excessive smoke that lingers inside and outside.
One great way to dry wet firewood is outdoor seasoning. This method involves stacking your firewood off the ground outside and covering only the top, making sure there's good airflow while protecting it from the rain. You may also consider splitting the logs to speed up the overall drying process.
The worst firewood to burn falls into two categories: toxic and highly inefficient. You should never burn wood that produces dangerous chemical fumes or excessive smoke, nor wood that burns too quickly or spits hazardous sparks.
Most hardwoods (like oak, maple, ash, elm etc.) require at least 6-12 months to season properly, and sometimes even longer (up to 18-24 months for very dense wood or large pieces). Softwoods (like pine, spruce, cedar) dry faster, often within 6 months.
High-quality moisture meters can achieve an accuracy within 0.1% of the wood's moisture content, offering consistent and reliable readings. The accuracy largely depends on the meter's quality and brand. The accuracy of the less expensive digital moisture meter can vary from 5 to 20%.
Readings of 5 to 12% are considered normal, and up to 17% is considered acceptable. Wood starts to rot and is susceptible to mold when its moisture content reaches 35 to 50%. Wood can typically hold up to 25% without showing signs of deterioration.
However, if you have a smaller fire pit (less than 3 feet in diameter), you may only need 2-3 logs per hour. Conversely, for larger fire pits (over 4 feet in diameter) or if you're aiming for a roaring fire, you might need 5-6 logs per hour.
For already seasoned (previously dried) firewood, rain only wets the surface and usually dries out in 2 to 3 days when stacked neatly in a sunny, breezy spot.
Burning wet wood has two negative consequences:
Your fire will smoke more, causing creosote build up in your stove and chimney. Your wood will burn less efficiently, costing you more to create the same amount of heat.
Wait at least 6 months and up to 12 months for dry firewood depending on the type of wood. Hardwoods such as oak and maple dry more slowly than softwoods such as pine and spruce. To ensure dry firewood, wait at least 12 months before burning.
You can check wood moisture without a meter by using an accurate kitchen scale to do an oven-dry weight test, performing a soap test, or evaluating visual and physical signs like color, weight, and sound.
Normal moisture content for wood generally ranges between 6% and 14%, depending on the environment and usage. For interior woodwork and furniture, 6%–8% is ideal, while exterior wood or construction framing typically ranges from 9%–14%. Readings over 16%–20% indicate excess moisture that may require drying to avoid issues.
Several common signs that conditions of excessive moisture exist in the home environment include the following:
Water can enter your home by leaking or by seeping through basement floors. Showers or even cooking can add moisture to the air in your home. The amount of moisture that the air in your home can hold depends on the temperature of the air. As the temperature goes down, the air is able to hold less moisture.
Wet or green wood requires enormous amounts of energy to burn, essentially wasting heat just to evaporate the internal water content. According to Firewood Farm, wood with moisture content over 25% creates multiple problems during burning. Ideal firewood moisture content sits between 15-20%.
Accuracy
While pin-type moisture meters may not be as fast, they excel in accuracy. Compared to pinless meters, pin-type meters deliver more reliable data.
You should be aware that a moisture reading of 0-15% is quite normal and gives no cause for concern. However, moisture readings in excess of 15% indicate the need for further inspection. Levels between 25-30% indicate that there may be water ingress, meaning that remedial work could be required.
While warm, dry summer days are ideal for this, winter weather works too—you just need to understand the process. Cold air is typically drier air, which actually helps draw moisture out of wood. Even when temperatures drop, as long as your wood is properly stored with good airflow, the seasoning process continues.
Moisture is drawn out of wood through evaporation, which is driven by an environment that features warm temperatures, low relative humidity, and active airflow. The drier and warmer the surrounding air, the faster it will absorb the moisture escaping from the wood fibers.
Ton Bag of logs
However, experience has shown us that typically a bulk bag of firewood will last a customer 6-8 weeks.