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Kiln Drying
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The Science of Kiln Drying
In order to minimize shrinkage and twisting, wood must be conditioned to the moisture content it will assume in the months and years after construction.
Our kiln-dried components average less than 19% moisture (less for Strata logs) per kiln charge.
Cants (large stock dimensional lumber) are stacked and placed in a sealed building, and the temperature is slowly raised to 170 degrees F. A consistent drying rate is carefully monitored and maintained throughout the kiln, while the moisture-laden air is removed by dehumidifiers. To determine the moisture content of the cants, Kuhns Bros. uses the "oven dry" process, which is considered the most accurate by industry experts. When the logs average less than 19% moisture content, they are ready for milling to the final log profile.
Our process of kiln drying produces logs with these superior attributes:
- Pre-shrunk - minimizing in-service checking, warping and twisting.
- Sanitized - high heat kills mold, fungi (which cause wood decay), as well as insects, their larvae and eggs.
- Crystallized Pitch - reducing the possibility of pitch seeping to the surface of the log wall.
- Dryer Log Surface - allowing for instant applications of finishes, which absorb deeper and last longer.
- Reduced Weight - lowering shipping costs while making logs easier to handle.
- Higher Insulation Values - providing better in-home comfort and reduced energy costs.
Our Kiln Drying vs. Their Kiln Drying
1. What temperature levels are achieved?
The temperature in our kilns is slowly raised to 170 degrees F. The advanced technology in our kiln controllers keeps the environment inside our kilns regulated throughout the entire process. This consistent drying rate throughout the kiln produces logs and other wood products that are properly dried and therefore much more stable and uniform.
2. What process is used in determining the moisture content of the logs-the "moisture probe," the "oven-dry ratio" or other?
Kuhns Bros. utilizes the "oven dry" process, which industry experts consider the most accurate. This method uses samples of the actual logs being dried in the kiln. The samples are weighed, dried completely in a laboratory oven, and then weighed again. The ratio between the two readings represents the average moisture content of the logs, inside and out. The "moisture probe," used by many log home manufacturers, measures only the outside portion of the log, which tends to be the driest, but does not accurately represent the average moisture of the entire log.
3. What moisture content are the logs dried to, and is the moisture content guaranteed in writing?
Kuhns Bros. log and timber components are dried to an average of less than 19% moisture content per kiln charge, which is guaranteed in writing.
The Hard Facts About "Air Drying"
Most log home manufacturers provide "air-dried" logs, which are seasoned in open-air storage yards where there is little or no control over the environmental conditions. The moisture content of these logs is not controlled, specified, or guaranteed. Local climate and weather conditions impact the seasoning of these logs, so the results are unpre-dictable. Air-dried logs are not heated or sanitized, therefore mold, fungi, insects, and sap are not killed Most dramatically, when building with unseasoned logs, you must make allowances for the "settling" or shrinking of the logs after they are placed in service. This increases the opportunity for costly issues to develop months after completion.
or eliminated.