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Exterior Corners
© 2008, Kenton Shepard
Exterior corners are areas with a lot of opportunities for problems since many logs meet in this area, each log a different shape and each of which will change shape differently as it dries. Cutting notches so that they remain tight after logs have finished shrinking requres knowledge and skill.
Homes built from green logs especially can be tricky. Good builders using green logs typically use a process called "underscribing" in which notches are slightly undercut. As logs dry and shrink, corner notches will open, allowing for a tight fit once drying is complete.
LOG EXTENSIONS
The ends of logs which extend past corners are called "log extensions" or "flyaways". Inspectors will see them cut to different angles or shapes, but what matters is that they be cut and asembled in a manner in which they will not trap moisture. Inspectors will see many, many that do. Inspectors may want to describe the condition and the problems it can cause and let it go at that.
Extensions which are left long are more heavily exposed to damage from weather, sun and impact. Because the end-grain is the most moisture-absorbent part of the log, it should be protected as much as possible by the roof overhang and maintained by diligent application of a moisture-permeable sealant.
CORNER NOTCHES
NOMENCLATURE
Although we will use names here to roughly differentiate between corner notch types, you can be sure that someone somewhere will take exeption to the name used because they've always called that particular notch by a different name. Inspectors can see examples of the variety of names for the same corner notch by looking in the builder section of the Buyer's Guides any of the major log home magazines.
SADDLE NOTCH
Saddle notches typically have a flattened "saddle" cut into the inner and outer upper surfaces of wall logs log where they will receive the notch of the log in the next round above. The photo at the left below shows chainsaw work being done on a saddle.
 
Courtesy of Robert Chambers
ROUND NOTCHES
In round notches, the upper log is typically scribed and cut to fit over the lower log.
 
Round notches- photos of a home which has been chinked and one in which moderate gaps have appeared. These gaps may allow air leakage.
Round notches in the home in the photo to the right have opened excessively. The inspector might recommend that the buyer consider sealing gaps with an appropriate sealant.
Determining the extent to which this condition will allow air leakage would typically require blower door testing.
DOVETAIL NOTCHES
 
Source
The photo above left shows a typical dovetail corner. Noticxe that the top of each log is not only notched, but beveled to encourage draining. The photo at the right is similar to a dovetail but is not a standard notch.
PINK and PURPLE NOTCH
That's as good a name as any. There is no widely-accepted name for the one-of a kind notch shown in the photo to the right.
As long as it is self-draining, tight, structurally sound and preferably a design which interlocks to some degree, this notch type is perfectly acceptable.
Source
All photos not cited are by Kenton Shepard Peak to Prairie Inspection Service
Sources for More Information
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