State of the Art Log Technologyby Hochstetler Log Homes on 2019-09-14 14:13:09
Although it may seem a stretch to unite the basic age-old log with today’s advanced technology, recent changes in the configuration of the log as well as log building systems themselves, have moved the industry to the forefront in “building green.” And, although the log home is hundreds of years old, there are ongoing innovations which still make the log a viable building material.
One of the first major innovations in making the log more energy-efficient was the design of the tongue-and-groove configuration, which not only sealed off the surface between the logs but helped the builder stack logs faster, easier and straighter. So, beginning with a groove on the bottom surface and a raised tongue on the top - a newer, more efficient system was created. Over the years, after much trial and error, many design changes were made until today when logs are extremely tight fitting and energy- efficient. The image in our main graphic shows our current profile. Unfortunately, since these features are hidden they don’t receive the attention they deserve, but are nevertheless essential to the overall performance of the log.
Critical to any building system is a strong and solid foundation and a log wall is no exception. Notice how the top log rests securely on the bottom one with wood-on-wood in three areas. So even as a log dries it will be “locked-in” and will seal off any air or moisture infiltration. Another key feature in the prevention of moisture infiltration is the placement of the outer tongue. By placing it close to the outside (the weather side) it will halt any moisture from working its way between the logs and eventually rotting them. A flexible 1/2”gasket is placed atop the tongue and, when the logs are stacked, is compressed to further seal off the area between the logs. The tongue is also tapered which makes it much easier for the builder to stack the logs and keep them aligned. The drip edge is another feature which diverts moisture from between the logs and down the wall. The most recent design change is the recessed notch which insures that logs will remain solidly in position even as the logs dry. Most of our recent log profiles incorporate a double tongue which gives you increased energy-efficiency. Regardless of the size of log you choose, each one has these important features so you can rest assured you are buying among the most technologically advanced logs in the industry.
As important as the consideration of the log itself is the drying method. Many manufacturers will only offer one method so your choice is limited, but the most common are air-dried, kiln-dried, and dead-standing. Air-drying means the cants (square timbers that are milled into logs) are stacked outside, preferably where they receive lots of sunshine and a prevailing wind, until they are relatively dry. This can take over a year, but even then they are not as thoroughly dried as kiln-dried and subject to some settling. The cost is less than kiln-drying, however. Kiln-drying means cants are stacked in a dry kiln and heated at temperatures up to 150 degrees for as long as it takes to get to the required 18-19% average moisture content level. This, in addition to having dryer logs, also has the benefit of assuring the logs are sanitized, killing any larvae or bugs that may have entered and also it “sets the pitch,” which eliminates most of the seepage of the sap. We use a combination of the two methods—air-drying for a minimum of 6 months and kiln-drying for 10-20 days, or as long as it takes to get them down to 18-19%, before processing. This is the best way of insuring there will be minimal settling in your logs. Our McKay model, which was built with kiln-dried logs, only settled about 1/2” for the entire wall. Some folks are hesitant to buy a log home because of the settling issue but if built by an experienced builder and in accordance to our construction manual you should have no problems. A third drying method, more common out west, is dead-standing. These trees are usually the victims of nature—storms, fires, insects or disease. Bad sections are removed and the resulting timbers are harvested and sent to sawmills where they are cut into cants. Like air-drying, this is an inexact science so the moisture content is unknown. Also with these you can potentially carry in unwanted visiting insects. We do not recommend these for a home without first kiln-drying them.
The selection of the log species is another energy-efficiency consideration. All logs are not created equal. R-value is the common index for measuring a log’s insulation value - the higher the number the better. Many manufacturers will only carry one species, and not surprisingly, tout that as being the best. Of the most commonly used species of logs the Northern White Cedar has the best R-value: 1.41 per inch. Eastern White Pine, the most common log in the Midwest, also has a very good R-value: 1.32 per inch. Western Red Cedar at 1.09 and Cypress at 1.04 are next. But the issue of R-value is only a small part of the equation. You must also consider other factors like workability, decay resistance, shrinkage, and of course, cost. It is best to talk to your salesperson or designer before finally deciding on a specific log or drying method. They can provide invaluable insight and suggestions in finding a solution that is best for you.
In conclusion, take your time and compare various manufacturers and their products, always keeping in mind the importance of the log’s profile, that hidden area that is so vital in saving energy and saving you money in the process.