Using a moisture meter in the field to distinguish wet firewood from dry firewood

The National Firewood Association has newly published a primer on what type of moisture content is ideal for those who want to know the right type of fuel to burn!

NFA’s blog post, released this week, suggests that you should aim for wood that’s between 15 to 20 percent moisture content for the best results.

Wood over 20 percent moisture content is hard to light, and over 25 percent will make a sizzling sound when it burns. At 30 percent you will see water bubbling from the end, NFA says. Conversely, you don’t want the firewood to be too dry, as it results in a very hot fire that’s difficult to control and can warp and crack your stove and/or chimney.

On Chimney Safety Institute of America’s homeowner resources page, we address the reasons why you want well-seasoned firewood.

Well-seasoned firewood is easier to start, produces more heat, and burns cleaner. If your wood is cut 6 months to a year in advance and properly stored, the sun and wind will do the job for free. If you try to burn green wood, the heat produced by combustion must dry the wood before it will burn, using up a large percentage of the available energy in the process. This results in less heat delivered to your home, and acidic water and creosote deposited in your chimney.

CSIA VIDEO: “Why wet wood is a waste.”

Now, how do you guarantee the wood you are getting is ideal?

Methods that experienced wood burners use (if they don’t have a moisture meter handy) to determine if the wood is sufficiently dry or is good fuel would include sensory indicators. They range from odor, wood weight, the condition or “checking” on the cut edge of the wood, separation of bark, and a musical ring that two pieces of dry wood make when knocked together.

CSIA VIDEO: “What seasoned firewood should sound like.”

But, you should go to the trouble of using a meter, because the data is quantifiable.

The National Firewood Association suggests that when you are buying firewood, you take four readings with your measurement tool, including on the face of the wood, dead center; with that, you can determine the actual moisture content with a fair degree of accuracy.

CSIA VIDEO: Struggle with having enough seasoned wood? Buy two years’ worth.

Some CSIA Certified Chimney Sweeps recommend to their customers that they resist the temptation of immediately burning the firewood that’s freshly bought, and instead give it time (and protective conditions) to age appropriately.

CSIA VIDEO: “How to select firewood.”

The Alliance for Green Heat took note of National Firewood Association’s important blog post and stated on its Facebook page: “All firewood dealers and energy auditors should … show the homeowner what the moisture content of their wood is. Especially when you are having wood delivered, test the wood BEFORE its dumped. Ask the firewood dealer if he can bring a moisture meter. Otherwise, you can pick one up at hardware for about $20.”

If you have questions about firewood and other solid fuel use as it pertains to chimney performance and safety, contact your local CSIA Certified Chimney Sweep. Use CSIA’s free zip code locator.


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