How to check whether your firewood is dry

It's easy to assess how moist a piece of firewood is. In this article you'll learn four easy ways to determine the moisture content of your firewood.

Lighting a fire with dry firewood is best

It is important to use dry firewood when lighting a fire in order to get the most out of your firewood and your wood burning stove. With dry firewood, you’ll get the best combustion.

Firewood is dry when its moisture content is lower than 18 %.  The moisture content in firewood indicates the amount of water in the firewood expressed as a percentage of the firewood’s weight. A piece of firewood weighing 1 kilogram with a moisture content of 20 % contains 200 grams of water. (Source: Lars Mytting’s book Norwegian Wood)

When you buy dry firewood from a dealer, the moisture content must not exceed of 20 %.

Why should you light a fire with dry firewood?

You should use dry firewood because it ensures you the best combustion and that you’ll get the most heat out your logs. The efficiency is much higher when you light a fire using dry firewood as opposed to using moist firewood.

If you use moist firewood, it is both damaging for the environment and often it will be uncomfortable for your neighbours because of the smoke generation that it will cause.

How to check whether your firewood is dry

There are different methods for checking whether your firewood is dry enough to light a fire with.

• Test your firewood using washing-up liquid
• The sound test. Banging two logs together will give you an indication of your firewood’s dryness
• Look at the logs. Dirt, mould and fungi are signs of moisture
• Wood moisture meter. How to get the concrete figures detailing the moisture in your firewood

Soap test – blow on the firewood

It is easy to test your firewood to see if it is dry – you can use regular washing-up soap

How to do it:

1. Add a little soap on one end of the log
2. Put your mouth near the other end and blow through the log

Your firewood is dry if bubbles appear. This happens because there are some channels inside the log which transport water. When the wood has been cut and dried, the water disappears and air can pass through when you blow.

Use the sound test

You can also test the driness of your firewood by banging together two pieces of wood. Your firewood is dry when the sound is hard and ringing. Moist firewood has a dull sound.

Be aware of pitfalls when it comes to the sound test. In frosty weather and when the temperature is below 0° Celsius, fresh wood can give off a high and ringing sound even if the wood is not yet dry.

Remember that the sound test only provides you with a superficial impression of the condition of the wood. It won’t always disclose whether the wood is dry at the core.

Look at the firewood

Your intuition is also a useful tool when it comes to assessing the moisture content of the firewood. Below is a dry firewood check list:

Firewood must be…

• dry
• clean
• hard
• having dry cracks on the ends
• without mould and fungi
• the smell of resin and juice disappears as the wood dries
• having clearly visible growth rings
• light in colour. Sun exposure makes the wood yellow and old wood turns greyish. Often the bark will separate from the wood.

If your firewood matches the criteria, it’s a sign that your firewood is dry enough for firing with in your wood burning stove. (Source: Lars Mytting’s book Norwegian Wood).

Use a wood moisture meter

You can also use wood moisture meter for measuring the moisture content of your firewood. With a wood moisture meter, you’ll get the most precise information on the moisture content in your firewood.