How to Test Firewood Moisture Content

Moisture content is one of the most important factors to consider when purchasing firewood. I learnt this early when I bought a house with a chimney and began buying firewood.

Shortly afterwards, I bought this non-destructive firewood moisture meter. I wanted something that was versatile enough to be used with firewood and could also be used with masonry and plasterboard.

Moisture content is important because it affects how quickly your fire will start and stay lit.

Some quick tips worth considering when buying firewood is;

  • Look for wood with less than 20% moisture content as it will burn quicker. 
  • Dry wood is easier to ignite but may smolder if there’s not enough oxygen available for this fuel source.
  • Wet wood is more smoky and difficult to ignite, but may burn slow and steady. You would need a lot of wet wood to keep a fire going all night, so I wouldn’t recommend it especially if the temperature may not be high enough to make it worthwhile.
  • Wood with 40% moisture content will take a long time to dry out, and will be more difficult to light and maintain.
  • A moisture meter can be very handy, as it takes the guesswork out of buying firewood. Knowing the moisture content is also important for your safety as you have to ascertain whether or not the wood is safe to burn indoors.

What’s the Best Firewood Moisture Meter

Wood Moisture Meter - Digital Moisture Detector...
Top Rated
KLEIN TOOLS Pinless Moisture Meter for...
Wood Moisture Meter - Upgraded Moisture Meter for...
Name
Wood Moisture Meter - Digital Moisture Detector...
KLEIN TOOLS Pinless Moisture Meter for...
Wood Moisture Meter - Upgraded Moisture Meter for...
Weight
176.9 Grams
198.45 Grams
181 Grams
Dimensions
‎9 x 15 x 3 cm
‎15.77 x 7.32 x 3.56 cm
‎16.69 x 7.19 x 4.09 cm
Pinless Measurement
Wood Moisture Meter - Digital Moisture Detector...
Name
Wood Moisture Meter - Digital Moisture Detector...
Weight
176.9 Grams
Dimensions
‎9 x 15 x 3 cm
Pinless Measurement
Top Rated
KLEIN TOOLS Pinless Moisture Meter for...
Name
KLEIN TOOLS Pinless Moisture Meter for...
Weight
198.45 Grams
Dimensions
‎15.77 x 7.32 x 3.56 cm
Pinless Measurement
Wood Moisture Meter - Upgraded Moisture Meter for...
Name
Wood Moisture Meter - Upgraded Moisture Meter for...
Weight
181 Grams
Dimensions
‎16.69 x 7.19 x 4.09 cm
Pinless Measurement

Last update on 2022-05-14  / Images from Amazon Product Advertising API

What is a good moisture reading for firewood?

When you are looking to purchase firewood, the moisture reading is important for determining how much work you will need to put into lighting your fire.

A good moisture reading for firewood should be below 20% – 25%. Anything higher than that and you may have trouble starting your wood stove or fireplace.

Wood can be categorised in two ways: green and seasoned.

Green wood needs to dry before it’s able to burn efficiently while seasoned wood has already had time to dry out.

The end result is that green wood produces more smoke than seasoned which means you’ll have more soot buildup on your chimney or house if you use it often.

It’s important for your firewood to have an appropriate level of moisture so that it burns efficiently and doesn’t cause a soot buildup in chimneys.

Why does wood smoke?

Smoke is carbon dioxide and water vapour, the results of incomplete combustion.

Wood smoke is also a result of chemicals in the wood heating inefficiently as they are released into the air.

Why does wood smoke

When you purchase firewood that has a high moisture content, it will take more effort to light your fire. Damp wood also makes it harder for the flames to begin burning through the logs causing slow ignition times. This can be frustrating as you wait longer for your fire to catch and the flames to begin.

It’s important to know that different types of wood have different moisture readings.

Some firewood may contain higher levels than others but it doesn’t mean that they should be avoided completely. It just means you’ll need to understand how much work you will need to put in to get the fire started.

If you’re looking for good quality wood, look at buying seasoned wood with less than 20% moisture content for best results.

How do I test my firewood with a moisture meter?

Firewood can be a great alternative to fossil fuels when it comes to heating your home in the winter months. If it’s too wet, then you will need to give it some more time to dry out before you burn it.

It is important that you make sure the wood you plan on using is dry enough for burning – which means no more than 30% moisture content by weight if possible (or less).

Why does wood smoke

To test this with a moisture meter, here’s what you do:   

  1. Get your firewood stacked in a pile.
  2. Do a touch test by placing your hands on on a firewood log to see if they feel wet.
  3. Get your firewood moisture meter and use the little probe on top of the meter and insert into one end of each log.
  4. You’ll get a specific reading of the moisture content.
  5. Make sure you know the readings of each type of wood so that you can see if they do indeed have the proper level of moisture before burning it.
  6. Check the supplier’s description of what the acceptable moisture content of the wood you have is.
  7. If it’s too wet, leave it in a dry place for several weeks to reduce the moisture content before you try lighting it.

The ultimate goal is for your wood to have less than 25% moisture content which will ensure that it cooks properly, stays burning long enough to be efficient, and eliminates polluting smoke.

How to test wood for moisture – Other Options

When using firewood you should always make sure you choose dry firewood because it is much easier to light and it gives off the most heat out your logs.

It is not only more efficient but much higher when you light a fire using dry firewood as opposed to using moist firewood.

When using moist firewood, the amount of smoke you generate can be harmful to your health and inconvenient for your neighbours.

There are several different methods of checking how wet or dry your firewood as shown below –

  • Using washing up liquid
  • Checking the logs for mould and wet dirt
  • Sound test (hitting the logs against each other)
  • Using a moisture meter (as described above)

Using washing up liquid (Method 1)

  • To check if your logs are dry, simply take some water and mix it with a small amount of washing up liquid
  • Wet the surface of your firewood logs completely and leave them for around three minutes before wiping off with a cloth or towel.
  • Blow air into one end of your log and check for bubbles. If there are any, is shows that the channels in your log is dry eneough for air to pass through it. Moist logs will have moisture in the channels in the log and this will result in no bubbles when you try to blow air through it.

Visual checks of the logs (Method 2)

  • To check if your logs are dry, you can also check for mould or wet dirt on the body. If the surface of your log is wet then there is likely to be moisture in the centre.
  • Simply take a handful of soil or sand and rub it onto the surface of the log. If any sticks to your firewood log, then there is moisture inside your logs.

Dry firewood should

  • have cracks on either end
  • be clean of dirt
  • have a light colour from the drying process.
  • be free of a resin smell
  • not have any visible mould or fungi growth

Using the sound meter (Method 3)

  • To check if your firewood is moist you can hit one log against another to see if they create a hollow noise.
  • Dry firewood should sound drum-like and holllow. This will be easy to discern because the noise will be more of a thud.
  • Moist firewood should sound like knocking two boards together, this will have a duller sound to it.
  • Moist logs will often produce a thud or a hollow sound and then a “crick” as if they have split.

It is important to remember that using the sound test is not definite. It will only give you an educated guess of the condition of the wood. It won’t tell you for sure if the wood is dry or not at the core.

Wood Smoke Health Effects

A common misconception is that regular exposure to wood smoke will not harm a person’s health.

The biggest risk from constant inhalation of wood smoke is from Fine particulate matter, i.e. particles with aerodynamic diameter ≤2.5 μm (PM2.5).

These particles can find their way into your eyes and respiratory system, where they may cause watery eyes, runny nose, and other illnesses, like bronchitis.

In fact, regular exposure to wood smoke can cause a variety of adverse respiratory and cardiovascular effects in humans, including eye irritation, asthma attacks, chronic obstructive pulmonary disease (COPD), and lung disease. 

The most common health effect is an increased risk of cardiovascular disease.

How long does it take to dry out firewood?

Drying firewood is an important process that needs to be done before it can be used. How long does it take for wood to dry out? The time needed depends on the size of the pieces, how often they are split and if they are stored indoors or outdoors.

The drying time for firewood can also vary greatly depending on the type of wood and how you cut it. The best way to determine the dryness of your wood is to use a moisture meter or by using your sense of touch.

How long does it take to dry out firewood

Drying wood is a task that can take anywhere from 3 months to 18 months. You should ideally cut wood in January to store for August/ September the following year.

This allows your wood to properly dry out over the hot summer months to be ready for the oncoming winter season.

As a good rule of thumb, if it takes you longer than 5 minutes to light your fire – then it’s too green/ wet and needs further drying.

How to dry firewood faster?

Firewood does need to be dried properly before it can be burned.

If you want to get your firewood ready for the winter, then here are a few tips on how to dry it quickly and efficiently.

  1. Cut up logs into smaller pieces that will reduce drying time by a factor of 10-12 times faster than whole logs.
  2. Place wood in an open area with good airflow for quicker drying times.
  3. Allow all sides of the log to be exposed to air by turning them every day or two so they dry from all angles equally and don’t warp when they shrink as much as possible during the drying process.
  4. Stacking the wood in a pile with lots of space between each piece is also another good trick to speed up the drying time for firewood.
  5. If you are stacking your wood inside, make sure it is at least 4 inches off of the ground and keep an eye on it in case it starts to warp or split.
  6. Keep your wood covered with a tarp during the drying process to protect it from the rain.
  7. Using firewood that is green or wet will end up costing you a lot of money because your fire will not burn well and you will have to keep buying lots of firewood .

Can you burn freshly cut wood?

Freshly cut wood has a very high moisture content. This will make it harder to light and maintain a fire using this wood. The sap and resin will also burn, making it emit more smoke that can be hazardous to your health.

These factors make freshly cut wood awkward to burn and not recommended.

When fresh cut wood has dried out, typically within 6 months after cutting, the moisture content will be reduced by 50%. It is then safe to burn the logs after they have been dried out properly.