The biggest problem with firewood, is getting it to season (i.e. dry out) properly. But, can you go too far with your seasoning?
In other words, can firewood be too dry?
Firewood does not become too dry under normal circumstances. However, if firewood is kiln dried or exposed to extremely dry and hot conditions, then it’s possible for the moisture content to fall below the ideal range of 15-20%, which causes the firewood to burn more quickly and less efficiently in wood stoves.
For most firewood burners, “overdrying” firewood is not really an issue. In fact, the University of Tennessee Extension goes so far as to say that:
“There is no danger in overseasoning wood – drier is better.”
With that said, there are two potential problems that you could run into if you have extremely dry firewood. We’ll cover those in a moment, but first, we need to establish the acceptable moisture level for firewood.
What Moisture Level is Acceptable for Firewood?
The ideal moisture content for firewood is 15-20% according to the EPA. And most other authorities (including the Cornell, University of Maryland, and University of Tennessee extension offices) agree that firewood should have a moisture level below 20% to be considered properly seasoned and ready to burn.
In addition, it’s common for these types of institutions to only provide a “maximum” moisture content recommendation, and to not even mention a “minimum” moisture range, because this is much less of an issue for most firewood burners.
With that said, let’s talk about the problems with extremely dry firewood.
Problems with Really Dry Firewood
Even though it is rare, and arguably a non-issue, it is possible for extremely dry firewood to cause some issues.
In particular, there are two main problems that you could encounter if you burn extremely dry firewood. They are as follows:
- The Firewood Burns Less Efficiently
- The Firewood Burns Too Quickly
Let’s cover both of these in a little more detail.
1. The Firewood Burns Less Efficiently
If you try burning extremely dry firewood in a modern woodstove, then it may actually burn less efficiently and produce more emissions than firewood that is in the ideal moisture range.
According to the EPA:
“Wood burns most efficiently when the moisture content is between 15-20%”
So, what happens when the wood falls below 15%?
According to the folks at woodheat.org, as wood gets drier it begins to produce smoke that is denser. And if a modern wood stove is full of extremely dry firewood, this can actually cause reduced efficiency because stoves are only designed to handle so much smoke at once.
To make this a little more clear, it’s helpful to understand that modern wood stoves are able to burn more efficiently by burning both the firewood you put inside AND the smoke / gases released by the wood. In fact, the gases that are released by wood can hold up to 60% of it’s potential heat.
So, to summarize: if a stove is filled with extremely dry firewood, this can produce more smoke / gas than the stove was designed to handle, which can cause some of the gases to be lost, increasing emissions and reducing efficiency.
2. The Firewood Burns Too Quickly
When firewood is burned, one of the first stages of the combustion process, is to evaporate all remaining moisture in the wood.
When there is less moisture in the wood to begin with, the wood will burn more quickly (and more hot).
You might think this is good, because you get a faster and hotter blaze. But, it can be a bit of an issue because you might need your fire to burn for a long time.
For example, you might need your fire to burn all night long, to keep your house warm overnight during winter. In this case, you’d rather have a slow and long burn, than a short burst of intense heat.
So, keep that in mind, especially if you are using a wood stove as the primary heat source in your home. The ideal moisture content in this situation is still 15-20%, and personally, I’ve found that well seasoned Black Locust or Hickory wood are ideal “overnighter” logs.
With that said, it’s also worth mentioning that this is probably less of a problem if you intend to use your firewood for outdoor campfires, because a fast burn is likely not an issue in that case.
Easy Fix When Burning Extremely Dry Firewood
So, what do you do if you have some firewood that is extremely dry?
If you intend to use the firewood for a wood stove, then a simple solution would be to mix your really dry wood with some regular seasoned wood. For example, if you have some wood that is 10% moisture content, you could mix it with some wood that is around 18-20% moisture content.
That way you can balance out the overall moisture content of your wood.
But don’t take this too far by mixing in wood that is not yet fully seasoned. For example, don’t mix your 10% moisture content wood with 30% moisture content wood. You should never burn wood that is not properly seasoned to below 20% moisture content.
How to Tell if Your Firewood is Too Dry?
Now, another question you might have, is how you can tell if your firewood is too dry or not.
Well, the most precise approach would be to use a moisture meter to determine if your firewood falls into that magical 15-20% moisture range.
If you don’t have a moisture meter, you can use our affiliate link to jump straight to this popular moisture meter on Amazon (*we get commissions on these at no cost to you).
And you can get a 2-minute crash course on how to use your moisture meter, with the video below:
If you don’t want to bother with using a moisture meter, then I’d recommend asking yourself the following questions:
- Was your firewood kiln dried?
- Has your firewood been stored in extremely hot and dry conditions for an extended period of time?
If you answered “no” to both of these questions, then it’s very unlikely that your firewood is “too” dry.
The reality of the situation, is that the natural moisture levels in the air will typically prevent your firewood from falling below 15% moisture content. The exceptions to this are when the wood is kiln dried or when the wood is stored in an extremely hot/dry place for a long time. When I say “extremely hot/dry place”, I’m thinking desert weather.
How Long Does it Take for Firewood to Dry?
Another topic that is very relevant to this conversation, is the amount of time required to properly season firewood.
The short answer, is that it takes 6-24 months to properly season firewood, depending on the species of wood, the way that it’s processed, the way that it’s stacked, etc.
I actually recorded a video on my YouTube channel, where I give an answer to this question that (I think) is a nice summary. I go into a few specific types of wood and compare their drying times as well, so if you know the species of firewood that you’re dealing with, you can probably get a ballpark figure for drying time using the below video:
