The correct moisture content for wood

I want to start out by making sure we understand what moisture content really is. When talking about moisture content, what we are looking at is the weight of the water in the wood with the actual weight of the wood itself. It is also known as the EMC ( wood Equilibrium Moisture Content) That ratio is viewed as a percentage. When we refer to EMC, we are looking the to see if the moisture in the wood is equal to the evironment. For instance, if you were to cut down a tree and measure the moisture, you will find that the moisture content would be between 30%-40% and even as high as 200% depending on the species of wood. The moisture content is high because the tree was living, therefore taking in water to stay alive. Now, if you were to walk through the forest and measure the moisture content of a tree that has fallen a year ago, you will find that tree to have considerably less moisture and find the EMC is similar to the environment because the water has been evaporating during that year.

Now, to answer the question that you are searching for. The correct moisture content for wood to start that project is no more than 2% of the moisture in the location where it will be used. You may be wondering how you would measure that. Well, you could go out and buy a moisture meter to tell you. That option is great if you are planning to make a lot of wood products, but some meters can be expensive. Another option is to store the wood in a room for a month or so, also called acclimating. When storing it in a room, what will happen is the wood being stored will eventually match the average moisture content in the room. That is what you want to happen.

When there is moisture in wood, the wood expands. Bringing the moisture down to match the humidity in the area, you are allowing the wood to shrink and bend to its natural state. Therefore, ensuring that the wood will not shrink at the joints, giving you a gap that wasn’t there when you first built it or bend, cup, and twist after you cut and milled it.

I personally like to shoot for 7% moisture in the wood I use for my projects. Depending on seasons, 7% may be impossible to make. If it is summer with high humidity, there are times when the moisture content in the area is above 7. As long as the wood is acclimated to the room you will be fine.

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