Q&A: Humidity in Wood

When you work with wood every day, understanding moisture content isn’t just helpful – it’s essential for delivering quality results. 

Whether you’re a seasoned cabinet maker or fairly new to the trade, these 5 questions about humidity in wood will help you avoid costly mistakes and create quality work that will stand the test of time.

Q: What is Humidity in Wood?

A: Humidity in wood refers to the overall moisture content (MC) that exists within the wood fibers.

Wood is like a natural sponge that absorbs and releases moisture from its environment. This happens because wood is hygroscopic, which means it naturally responds to changes in the relative humidity around it.

When the air is more humid, wood absorbs moisture. When it’s drier, wood will release moisture back into the air.

Q: What’s Acceptable Moisture Content for Cabinet Work?

A: For cabinet making and finer woodworking, moisture content should be below 16%. 

This is an acceptable percentage for indoor applications where cabinets will be in a climate-controlled environment. Some may recommend a lower target range for some hardwoods like oak, maple, and hickory.

Starting with properly dried lumber will set you up for success and minimize future movement issues.

Q: How Do I Measure Moisture Content in Wood?

A: There are 2 common options for checking moisture content. 

The most practical for day-to-day use is a digital moisture meter. They come in 2 types – pin meters that insert small probes into the wood, and pinless meters that scan the surface without leaving holes. For more expensive stock, pinless meters are sometimes preferred because they don’t penetrate the material.

Method #2 is the oven-dry test. This involves weighing a wood sample, heating it in a special oven at 221°F, and weighing it repeatedly until the weight stabilizes. While this method is highly accurate, it destroys the sample and takes considerable time, making it more suitable for quality control testing than everyday shop use.

Q: Why Does Wood Movement Matter For My Projects?

A: Wood movement is one of those facts of life that every craftsman needs to recognize. 

As humidity changes through the seasons, wood will expand and contract. Here’s why this is important – for every 4% change in moisture content, wood moves about 1% in width. That might not sound like a lot, but on a 24” cabinet door, a 4% moisture drop could cause it to shrink by nearly a 1/4-inch!

Understanding wood movement will help you plan for seasonal changes and design joints that accommodate natural wood behavior. It’s also why using wood that’s properly dried to match its final environment is so important.

Q: What Issues Can High Moisture Content Cause?

A: High moisture content in wood can lead to headaches that make installation difficult or impossible – like warping, bowing, cupping, and crooks. 

You might also see joints open up as the wood shrinks, or find decay if moisture levels stay high for long periods of time.

On the flip side, wood that’s too dry can become brittle and difficult to machine cleanly. It may also expand significantly when exposed to normal indoor humidity, which can potentially cause doors to bind or panels to buckle.

The key is to find the sweet spot where your wood is properly conditioned for its final home. By checking moisture content and allowing your wood to acclimate when needed, you’re investing in the long-term success of every project that leaves your shop.

Have Other Questions? Contact Meridian Products.

If you have more questions about wood selection or need expert advice for your next project, contact your Meridian Products sales or customer service representative. We’re here to help you succeed!