Kiln Drying Wood: Is it Worth It?

kiln drying log sidingAt Heartwood Mills, we believe kiln drying is absolutely worth the effort. So much so, that we consider this process to be an essential step in our production of milled wood building materials.

But why is it so important to remove the moisture from our Northern White Cedar and White Pine logs? And why don’t we let nature do the work by air drying the wood? Before we explain the unbeatable benefits of kiln drying wood, let’s explore the reasons why some mills choose to forgo this important process.


Reasons Against Kiln Drying Wood

There are generally two groups of mills: those in favor of kiln drying, and those that aren’t. Those that aren’t often site these reasons against it:

  1. It can be expensive. In order to operate a kiln, a mill must purchase, build and maintain the machinery. While this isn’t cheap by any means, at Heartwood Mills, we believe it’s worth the investment.
  2. It’s a complicated process. Kiln drying requires skill. This is especially true when working with round logs, when moisture removal and the subsequent shrinkage geometry makes it challenging to dry. Also, some wood species are more difficult to kiln dry than others. For example, sapwood has a much higher moisture content than heartwood. Those species with large sapwood rings, such as Pine, are even more difficult to dry.
  3. It can be time-consuming. Though kiln drying does take time — Heartwood Mills’ process can take from four days to three weeks, depending on the size of the lumber and its initial moisture content — but air drying takes time, too. Because we maintain a large timber supply for the convenience of our customers, it’s our practice to air dry logs first to reduce kiln drying time.

Reasons for Kiln Drying Wood

At Heartwood Mills, we believe the benefits of kiln drying wood outweigh the cons. The USDA states that favored drying procedures are those that bring the wood to “moisture content corresponding to the average atmospheric condition to which it will be exposed.” We believe that kiln drying is the best defense against:

  1. Checking and shrinking. This occurs when a log is dried and exposed to different environments. When this happens to load-bearing logs, it can lead to serious settling issues. While some splitting and checking will occur naturally in all logs, we make sure this happens in our kiln and not your house. Because our milled wood products are dried under controlled conditions, we can reduce the number of defects that occur. And after they’re dried, we inspect logs and remove defects that surface.
  2. Rot, fungus and mildew. Checking and splitting creates voids that become a breeding ground for moisture issues that can cause decay. Kiln drying logs in high heat also sanitizes the wood, killing off destructive pests and larva.
  3. Extra time and maintenance. To keep these issues at bay, homeowners have to be diligent about maintaining their homes, which requires time and expertise. You can stain and seal kiln dried logs right away to protect your log siding from the get-go.

Our Kiln-Drying Process

At Heartwood Mills, we use top-of-the-line equipment to ensure our customers get the best milled wood possible. We have two large equilibrium moisture content (EMC) kilns that operate on natural gas for maximum efficiency. EMC is defined as the point at which wood stops gaining or losing moisture. Using a system of heat and fans, our kilns add and withdraw moisture from our lumber until it reaches its EMC point — typically between 6% and 11%. Our custom-designed kilns are similar to those built to dry wood for fine furniture because we believe that our customers’ homes should be built with the same care and craftsmanship.

Quality homes start with strong foundations, so it’s important to select wood milled products that will stand the test of time. When planning your project, ask your builder about the moisture content of the logs selected and the drying method used. Our milled wood specialists also can answer questions you have about air drying vs kiln drying. Let us help you decide which option is right for you.