RippleCraft builds using only kiln dried logs with the moisture content reduced to an average of 15%. Kiln dried logs are perhaps the most important component in building a stable, check reduced home. It is not unusual for a log wall that has not been kiln dried to settle 2″-3″ is a wall measuring 8′ in height. Our kiln dried logs will shrink less than 1/2″ in that same wall. This makes the house more stable, reduces checking, and makes for a tighter fitting home. The kiln drying of logs is more than simply baking the wood dry. The drying must occur in a controlled environment that allows the wood to remain in moisture equilibrium. In other words, the outside of the log cannot be allowed to dry too quickly before the inside also has an opportunity to dry. It is a moisture imbalance during the natural drying of wood that causes much of the twisting and creates a majority of the cracks or “checks” common in log homes. There is no way to entirely eliminate checking and twisting as this is the nature of wood. However, the naturally occurring negative effects of drying wood can be minimized using proper methods. In the picture below, the log cross section will shrink more radially (from A-B) than it will tangentially (X-Y.) This varying shrinkage rate is what causes checking. Each truckload of timbers we receive has several samples removed that are weighed and then baked completely dry in a small oven. The samples are re-weighed at that time. The variance in “green” and “dry” weight constitutes the moisture level of the sample. A sample that weighed 20 pounds before drying but only 10 pounds after drying would have had an original moisture content of 100%. RippleCraft’s kiln drying process includes the close monitoring of the timber’s moisture level as the wood dries. The findings are closely logged onto a ledger so that each processed charge is documented. When monitoring reveals a moisture imbalance, steam is introduced into the 130 degree kilns to slow the drying of the exterior portions of the logs. The interior continues to slowly dry despite the steam as moisture seeps toward the outside of the log from it’s center. Kiln drying is a time consuming process. Many 8″ white pine timbers must remain in the kiln for up to three months or even longer to reach the optimum moisture level. RippleCraft maintains two natural gas kilns with a combined capacity of 112,639 board feet. The average amount of water removed from a 16′ 8″ log is more than 13 gallons. That is more than 17,000 gallons of water removed from the kilns in an average charge of 8″ timbers! Other benefits of kiln drying that aren’t specifically addressed above;
- Eight inch dry timbers are typically installed without the use of heavy equipment while the usage of green timbers in that size can necessitate the use of a crane, sky lift or other equipment.
- Timbers that are not dried shortly after harvest will stain. Dark patches of blue stain will begin to develop (especially in high and humid temperatures) within several weeks of harvest. Unlike natural weathering, blue stain can permeate the wood inches deep and cannot be sanded off.
- The eggs and larva of wood destroying insects can be present in wood at harvest. Without kiln drying these pests can live generations in your home.
- Kiln drying crystallizes pitch in pine. Wood that is not kiln dried or improperly dried, can bleed pitch forever–especially in a southern exposure.