Most houses’ weight is supported vertically, but a log home’s structural support comes horizontally, with the load of the house and its components resting almost entirely on its perimeter log walls. It’s critical that they be built to precision. This is known as the joinery system.
The load-bearing surfaces that touch are known as the horizontal surfaces. These surfaces form the top and bottom of the log profile, or its shape as viewed from the end. The sides of logs are known as its visible surfaces and define the look of the logs when stacked.
There are many different horizontal interface designs to account for the natural tendency of logs to shrink, swell and twist as they dry (for examples, click here!). Wood species react differently during their seasoning process, so producers design a system that works best for them by taking into account the type of wood they’re using, its moisture content and the logs’ size and profile. One approach is not superior to another — much depends on your selections and personal preferences.
Besides providing structural stability, the horizontal interface must allow for a weathertight seal. Many manufacturers cut grooves and channels to accommodate sealing adhesives — usually foam or caulking — and create an impenetrable bond.
Other refinements in the horizontal interfaces are checking and drying grooves and drip edges. The checking-drying groove lets air reach the log’s inner core so it dries at the same rate as the log surface to minimize checking. Because upward-facing checks can collect moisture, these grooves tend to concentrate checks that do occur along the bottom surface of the logs, where they’re less likely to catch and retain moisture.