What’s a Good Moisture Meter Reading Based on Your Project?
So you want your next wood project to be successful. And you know how important measuring and monitoring wood moisture content is.
Your moisture meter, of course, will tell you the moisture content (MC) of your wood. But how do you know that the MC measurement you’re getting is good for the kind of project you want to work on?
If that sounds like a question you have, then you’ve come to the right place. In this article, you’re going to learn all about acceptable moisture readings for your project. Whether you’re working on indoor projects or outdoor projects, we’ve got you covered.
We’ll talk about
- Acceptable moisture readings
- Factors that affect the MC reading you want
- The impact that species has on your moisture readings
Let’s start with the reason you came here: to figure out an acceptable moisture reading for your project.
What is an acceptable moisture reading for your project?
Without a doubt, it’s important to know how wood will respond to a given environment. The acceptable moisture reading for your project is going to depend less on what your project is and more on where your project is.
Acceptable moisture readings for outdoor projects
If you’re working on outdoor projects or projects that will be exposed to the elements for a considerable amount of time—like decks, sheds, fences, arbors, or gazebos—then you simply need to make sure that the MC of your outdoor project is under 19%.
The reason you want to keep the MC of your outdoor projects under 19% is that at 19% and above, you run the risk of mold growth, and that’s bad news for your project and your clients.
As long as you have an MC below 19%, your outdoor projects should be fine.
Acceptable wood moisture content for construction projects
When it comes to construction projects, many framers would rather work with wet wood and then deal with the consequences later, if there are any.
So, for construction projects with exterior wood or building envelope components made of wood, an MC between 9% and 14% is best!
Acceptable wood moisture content for indoor projects
On the other hand, if you are working on indoor projects where the wood is 1) visible and 2) needs to remain unwarped and in pristine aesthetic condition (furniture, flooring, musical instruments, cabinetry, etc.), then the MC of your project’s wood should be more carefully determined.
Specifically, the MC of your indoor projects must be within 2% of the equilibrium moisture content (EMC) of the location or, even better, equal to the EMC of the location. Anything over 2% difference from the EMC of the location is an unacceptable measurement. At that point, you either need to acclimate the wood, dry the wood, or purchase new wood altogether.
Let’s learn a bit more about EMC and how it might impact the moisture reading you want from your meter.
Factors that can impact the appropriate wood moisture content reading
The first factor that can impact what kind of moisture reading you want from your meter is EMC—one of the most important pieces of data that you can know for your projects.
EMC varies depending on the geographic location. For example, the EMC in Florida is going to be very different from the EMC in Arizona. Because wood is hygroscopic, it will absorb or release moisture until it reaches the EMC where it is placed or installed.
However, if the wood at the time of purchase is already at the correct MC to match the EMC of its end destination, then you can be confident that the wood will be stable. This also means that you won’t have to worry about extreme swelling, shrinking, warping, or cracking. This is ideal!
At the end of the day, the EMC is going to be the most important factor that will affect the kind of reading you want from your meter. But, there are two factors that help to determine the EMC of a location:
Different geographic locations have different temperature and humidity levels.
However, humidity is the most impactful of the two. Again, our example of Arizona and Florida is helpful. Both locations are very hot, but both have totally different humidity levels.
If a location is very warm but has low relative humidity, the wood will release moisture until it matches the amount of moisture in the air. On the other hand, if a location is the same temperature but has a very high relative humidity, then the wood will absorb moisture until it matches the amount of moisture in the air.
Now we know some factors that influence what moisture reading you might want, but there is also one more thing you might want to consider: species.
Does species affect acceptable moisture meter readings?
The species of the wood you are working with will impact what moisture meter reading you get from your meter because different species are just that—different.
Each wood species has a specific density and chemical composition. These factors influence your moisture readings. It’s important to know the wood species you are working with so that you can add the correction for that particular species.
If you’re working with a Bessemeter moisture meter, this is as easy as simply selecting the correct species or specific gravity setting on your meter using the chart that comes with the manual for your meter.
In other cases, you might need to use a sheet or table for your meter that allows you to apply a correction factor for each reading.
However, no matter what species of wood you’re working with, always make sure the wood’s MC matches the EMC of the region. Species might impact your moisture meter’s readings, but it doesn’t impact EMC. So if the EMC is 8%, you want your wood’s MC to be 8% too.
Take on your woodworking projects with confidence!
Now that you’re equipped with the knowledge you need about MC measurements and how best to use them, you can tackle all your projects with confidence that you’ll avoid moisture-related failures.
Having a high-quality, easy-to-use, affordable moisture meter will help you get accurate measurements and make simple adjustments for species. Check out Bessemeter’s moisture meter buying guide for more information.