Why Kiln-Dried Wood Is Better Than Air-Dried Wood

Trying to decide whether to use kiln-dried wood?

It might feel like a tough call.

Yes, air-dried wood has been around for centuries—and there’s something romantic about the idea of using a more “natural” material.

But for a woodworker wanting to meet deadlines and have a successful project, kiln-dried wood is your best choice.

Think—little or no drying time. No dealing with wood that has too much moisture and the potential for a disaster. And no pests making their home in your wood.

Those are just a few benefits. We’ll get into more as we cover:

First, a quick review.

What is kiln-dried wood?

Kiln-dried or seasoned wood is wood that has been dried in a special type of heated chamber, similar to a low-temperature oven. The consistent heat and relative humidity, plus sufficient airflow, speed up the drying process and get the wood to the right moisture content.

There are four main types of kilns—conventional, dehumidifier, vacuum, and solar kilns. Though they function a little differently, they all lead to the same final product: wood that has been dried to a certain moisture content.

To learn more about kilns and everything involved in the process, read our guide to the kiln-drying process .

For now, let’s talk about the wood used by woodworking professionals.

What type of wood do experts use?

A professional woodworker using an orbital sander on a piece of wood that was kiln dried

In most cases, woodworking professionals, especially those with large-scale businesses, opt for kiln-dried wood. This is particularly true when they’re building furniture, installing flooring, or crafting musical instruments.

Kiln-dried wood helps them ensure that their wood is at (or can easily acclimate to) the moisture content needed for the project.

Framing is one possible exception to this generality.

Lumber for framing doesn’t need as low of a moisture content as wood for indoor projects. So, some experts may use air-dried wood that has reached an appropriate outdoor moisture level (about 12–14%).

And there’s a reason for this—wetter wood tends to be easier to nail in. And as long as the wood is close to the needed amount of moisture, it won’t warp too much.

Nonetheless, some contractors prefer to avoid the risk of warping altogether and opt for kiln-dried wood too.

Here’s why.

5 reasons to choose kiln-dried wood over air-dried wood

A pile of freshly milled green woodIn short, kiln-dried wood typically makes project success more likely than air-dried wood. And involves a lot less hassle.

Sure, you could meticulously stack your green wood, protect it from the elements and insects, and make sure it gets plenty of air circulation. But with all that effort, you’re still going to have to do some waiting. And that may not be worth it to you.

On the other hand, kiln-dried wood:

  1. Ensures you get the right moisture content
  2. Decreases your chance of moisture disasters
  3. Increases stability and quality
  4. Destroys pests, mold, and fungi
  5. Saves money and time

Here are more details:

1. It ensures you get the right moisture content

A kiln, with its consistent heat and air circulation, is the most effective way to be sure that your wood ends up with the right moisture content. It can get wood to a lower moisture content than air drying.

Particularly if you live in a wet climate.

In a region with high humidity levels, you can air dry wood for many years and still never reach a low moisture content because the equilibrium moisture content (EMC) outdoors is much higher than what is needed indoors.

2. It decreases your chance of moisture disasters

Wood with too high of a moisture content can shrink, ruining a project. It can lead to issues like:

  • Warping and twisting in furniture or other wood items
  • Buckling, cupping, and crowning in flooring
  • Adhesives not holding together

Kiln-dried wood can help you start off at the right moisture content or at a point where only a little acclimation is needed.

3. It increases stability and quality

Stacks of wood that have cracked during the air-drying processWhen wood has been kiln dried, it’s more likely to reach a point of stability.

Chris Marshall, expert woodworker and editor for Woodworker’s Journal, says:

“Once wood is dried to 8 to 10 percent moisture content in a given shop environment, it is ‘stable’ for woodworking.”1

He says it “doesn’t matter whether that drying process happened in a giant oven or stickered and covered in someone’s barn for a few years.”

In other words, the wood could have been kiln dried or air dried, but what matters is that it reaches 8–10% MC.

The problem? Outdoor conditions often prevent wood from drying down that low.

Furthermore, as lifetime woodworker Tim Inman points out, wood tends to be more uniformly dried when it’s been in a kiln. Air-dried wood can have pockets of moisture, particularly near the center of a board.2

And on a final note about quality, woodworkers must consider that drying wood outdoors can lead to damage: damage from inconsistent drying conditions, weather damage, or insect damage. Avoid all of that with kiln-dried wood.3

4. It destroys pests, mold, and fungi

Leaving wood outdoors is like leaving an “open house” sign outside your home all the time—only worse. Pests see it as an invitation to come right in and stay!

Think powder post beetles, ash borers, and termites.

And fungus and mold—if the wood is wet and not drying quickly enough.

Heat sterilization of wood to prevent pests, mold, and fungi occurs at 133° F for 30 minutes, according to the USDA Forest Service. And kiln drying typically reaches that temperature without a problem.

Goodbye to any unwanted guests that could end up in your home or a customer’s home!

5. It saves money and time in the long run

As a woodworking professional, you no doubt have experienced the frustration and cost of a damaged project.

By using kiln-dried wood, you cut your risk of damage because you’re getting wood at the right moisture content and avoiding moisture disasters and pests.

That spells time and money saved in the long run—for both you and your customer.

After reading about all these benefits, you may be convinced that kiln-dried wood is for you. But even if you’ve chosen kiln-dried wood, it’s important not to relax too much.

There’s still one crucial step for woodworking, no matter what…

Check even kiln-dried wood for moisture

That’s right. Kiln-dried or not, checking your wood for the proper moisture content is essential.

You might have acquired kiln-dried lumber from a reputable manufacturer or lumber yard. But there’s still the possibility of variation in moisture content. Enough to destroy your project.

Perhaps the wood wasn’t stored well, or some moisture got in during transportation.

Whatever the case, checking your wood with a quality wood moisture meter and allowing it to acclimate properly before use can help ensure a project with no regrets. To learn more about acclimation,

  1. “Why Is Kiln-Dried Better Than Air-Dried?” Woodworker’s Journal, April 15, 2014. 27. ()
  2.  Ibid. ()
  3. Introduction to Kiln Drying, Nyle Systems. ()