Most people who deal in lumber and purchase it for their construction projects know the importance of kiln drying. Properly kiln drying lumber can prevent all sorts of problems, such as warping, cracking, and cupping in the future.
North American vs. European Moisture Content Standards
Did you realize, however, that there are different standards for kiln drying lumber in North America versus Europe? Where your lumber originates and the standards they use to dry lumber can make a big difference in the overall moisture content of the kiln-dried lumber in your order.
The North American lumber market’s accepted standard for moisture content of kiln-dried lumber is only 6-8%. Contrast those numbers with the European lumber market’s standard of 12-15%. Why the discrepancy, you may wonder? It’s due to the differences in the North American and European climates, with North America being drier and Europe being wetter.
Do the Varying Standards Make a Difference?
If you’re going to use the lumber you buy in an exterior application, your project may turn out okay even if you use lumber that is kiln dried just to the higher European standard moisture content levels. But if you’re using the lumber for interior jobs or in a particularly dry region of North America, you can encounter serious problems if you exceed the lower North American standards. These standards aren’t arbitrary. They’ve been set for a reason. Lumber with a higher moisture content simply doesn’t perform well in a dry climate.
Why Do the European Standards for Kiln Dried Lumber Matter if You’re in North America?
You may be wondering why we would even bother to bring up the different standards for moisture content of lumber in North America vs. Europe. After all, you’d probably assume that any lumber sold as kiln-dried lumber in North America would automatically go by North American standards. That assumption, however, would not always prove to be accurate.
Many Mills Around the World Kiln Dry Their Wood to European Standards
This may come as a surprise, but European kiln drying standards for Lumber are the norm in many places in the world. This is thanks in large part to European control of the mills. Because of past colonialism and imperialism, a significant number of mills across the globe are still under European company leadership. This is especially true for species such as African Mahogany, European Beech, French Oak, Utile, and Sapele. The lumber made from these African and European species all tends to come to North American markets kiln-dried to European rather than North American standards. Before that lumber can be used in much of North America, it needs to be re-dried to meet our standards.
In our next article in this series, we’ll look at what exactly is entailed in this re-drying process. This information is important to keep in mind if you order any exotic lumber from overseas. You should make sure that whatever lumber yard you’re dealing with has gone the extra mile to re-dry the lumber to the lower North American standards for moisture content.