The process of kiln drying reduces the amount of moisture in the wood products used to build a log home. In order to minimize shrinkage and twisting, the wood must be conditioned to the moisture content it will assume in the months and years after construction. Kiln-dried components with an average of less than 19% moisture (less for Strata logs) per kiln charge are standard with every CLC home package. As part of the CLC Quality Assurance Program, all wood products are also graded by certified inspectors in accordance with the Log Homes Council grading standards and backed by our 25 year warranty. The Kiln-Drying Process Cants (a stack of large dimensional lumber) are placed in a sealed building and the temperature is slowly raised to 170º F. A consistent drying rate is carefully monitored and maintained throughout the kiln, while the moisture-laden air is removed by dehumidifiers. CLC uses the "oven dry" method, which has a greater accuracy in determining moisture content in large timbers. When the logs average less than 19% moisture content, they are ready for milling to the final log profile. It costs more to kiln-dry logs, but CLC believes this is the best investment a log home owner can make in their log home for the following reasons: 1. Kiln-dried logs are "pre-shrunk" before milling to a final profile, making them stable and uniform compared to unseasoned logs. As a result, no severe shrinking or warping occurs. 2. In-service checking, warping and twisting is minimized since it occurs in the kilns prior to milling and final construction. Defective logs are graded out by trained inspectors and graded logs are stamped with the Log Homes Council Certification for Stress Grades. 3. Using high heat, the logs are sanitized, killing mold, fungi (which causes wood decay), plus insects, their larvae and eggs. 4. Pitch in the wood is crystallized, reducing the possibility of this sticky substance seeping to the surface of the log wall. 5. Interior and exterior finishes can be applied immediately following construction, which is more convenient and provides immediate protection. Also, applications absorb deeper and last longer. 6. More than 10,000 pounds of water are removed from the typical home, significantly reducing the weight of the logs. As a result, even the longest logs are easily handled by two people. 7. Properly dried logs provide higher insulation values, reducing energy costs and increasing the comfort of the log home. Expert Recommendations on the Importance of Properly Dried Wood.
Logs used for house logs should be dried prior to being placed in service, and a reasonable target moisture content is 19%. That way, most of the shrinkage has already taken place. Building with "green" logs, which are harvested from living trees, will result in considerable shrinkage in walls of log homes and requires specialized construction techniques. Tom Gorman, Professional Engineer, University of Idaho. Proper kiln-drying procedures... control the drying environment and reduce the amount and severity of drying induced defects. Any piece of wood that has excessive warp or checking may be removed from the inventory prior to shipment to the customer.
Drying wood prior to installation provides an opportunity for the wood to maintain relatively stable dimensions during service. The advantages of kiln-drying include: 1. reduced drying time, 2. better control over the final moisture content, 3. reduce unwanted defects, 4. the ability to control drying in the center portion of the wood increases protection against fungal degradation, 5. temperatures above 160ºF or above solidifies the resins in softwoods, reducing the problem of resin bleeding. Paul Blankenhorn, Ph.D., Professor of Wood Technology, Penn State University. There are two important differences between air drying and kiln-drying. In a kiln, the wood is usually heated above 130ºF, which kills all insects, eggs, and fungi. Second, with resinous softwoods, the heat drives off the resin that would be liquid and runny at room temperature. Dr. Gene Wengert, Professor Emeritus in Wood Processing, Department of Forestry, University of Wisconsin, Madison.
