Kiln Dried Wood vs Air Dried Wood: Knowing the Difference

When embarking on a woodworking or construction project, one of the crucial decisions you’ll face is selecting the appropriate type of lumber.

Two primary options you’ll encounter are kiln dried wood and air dried wood, each with its unique set of characteristics and advantages.

In this article, we delve into the differences between kiln dried wood and air dried wood, examining aspects such as moisture content, drying times, stability, and availability.

By understanding these factors, you can make an informed choice when selecting the ideal lumber for your specific project needs.

Kiln Dried Wood vs Air Dried Wood

Before knowing their characteristics and advantages, you should understand what is kiln dried wood and air dried wood.

Kiln dried wood undergoes a controlled drying process, employing artificial heat sources and carefully regulated conditions.

The process involves placing the wood in a chamber where temperature, humidity, and airflow are carefully regulated to accelerate the drying process while minimizing the risk of warping, cracking, or other forms of damage.

On the other hand, air dried wood relies on the natural drying process, taking advantage of outdoor airflow to slowly reduce moisture levels.

According to popular woodworking, the wood is often stacked with spacers in between boards. Because it’s a completely natural process, air drying can take anywhere from 8 to 16 months or more, depending on the wood species and thickness.

Although air drying requires more time, it can be a cost-effective alternative and is often favored for its traditional appeal.

So, kiln dried wood and air dried wood are two different methods of drying lumber, and they have certain advantages and disadvantages. Here’s a comparison between kiln dried wood and air dried wood:

Comparison between kiln dried wood vs air dried wood:

1. Drying process:

Kiln Dried Wood: Kiln drying involves placing the wood in a large chamber or kiln where temperature, humidity, and airflow are controlled. The wood is dried using artificial heat sources, such as gas or electric heaters.

Air Dried Wood: Air drying involves stacking and exposing the wood to natural airflow in an outdoor setting. The wood is typically stacked with spacers to allow for proper air circulation and left to dry over an extended period, usually several months to a year.

2. Moisture content:

Kiln Dried Wood: Kiln drying allows for more precise control over the drying process, resulting in lower moisture content. The wood is typically dried to a moisture content of 6-8%, which makes it suitable for indoor use and minimizes the risk of warping, shrinking, or cracking.

Air Dried Wood: Air drying is a slower process, and the moisture content of air dried is generally higher compared to kiln dried wood. Depending on the drying conditions and climate, air dried can have a moisture content ranging from 12-20% or even higher. It may require additional time for acclimation before use in certain applications.

3. Time:

Kiln Dried Wood: Kiln drying is a faster process compared to air drying. It typically takes a few weeks to a couple of months to dry wood in a kiln, depending on the species and thickness of the lumber.

Air Dried Wood: Air drying is a slower process that can take several months to a year, depending on the climate, species, and thickness of the wood. It requires more time and space but can be a more cost-effective method, as it doesn’t require the energy consumption associated with kiln drying.

4. Stability and shrinkage:

Kiln Dried Wood: Kiln drying helps to stabilize the wood and reduce its moisture content more evenly, minimizing the risk of warping, twisting, or shrinking after it is used in construction or woodworking projects.

Air Dried Wood: Air drying may result in slightly higher moisture variations throughout the wood, which can lead to more movement, such as warping or twisting, once the wood is used. However, properly air dried wood can still be stable and suitable for many applications.

5. Availability and cost:

Kiln Dried Wood: Kiln dried wood is readily available at lumberyards and suppliers, as it can be produced on demand. However, the cost of kiln dried wood is generally higher due to the energy and equipment required for the drying process.

Air Dried Wood: It may be more readily available in certain regions where the climate is suitable for the drying process. It can be a cost-effective option as it doesn’t require the use of specialized drying equipment, but availability may vary.