About Settling and Shrinking

The words "settling" and "shrinking" invoke fear in the hearts of many future log home buyers. This shouldn't be the case, however, because the business and practice of building log homes has been around long enough such that the "problem" is well understood and is really not a problem any more. However, it's a topic that needs some understanding and consideration.

The Facts

Let's start with some facts. Logs are "wet" or "green" (contain a lot of water) when cut from the forest (exception: standing-dead trees used primarily in handcrafted homes). After being cut, logs will slowly start to lose water to try to match the ambient air moisture content. As logs dry, they shrink, which can cause checking, warping, and twisting. The degree to which these effects occur depends on the wood specie and drying environment. The purpose of managed drying is to pre-shrink logs and make them more stable before they are used in construction. When logs are stacked in log walls, even after drying, they can settle. Settling can be significant enough to require special construction techniques to compensate — or not.

About Settling

Settling is made up of two factors – shrinkage and compression. Both contribute to a possible reduction in height of stacked log walls. In a 10-course log wall, 1/8 inch shrinkage in each log means a total 1.25 inches for the wall. Significant settling can cause problems that range from serious (separation of walls from roof), to relatively minor (windows and doors that stick).

Shrinkage is a reduction in log dimensions. Some wood types shrink more than others. Some wood types shrink in different ways than other types. Individual logs of the same wood type can have different shrinkage characteristics. All woods shrink less when dry.

Compression is caused by the weight of logs stacked on top of each other. Fibers in the wood are forced closer together, which reduces the size of each log in a vertical direction. Compression between logs is good in that it helps create tight joints. Proper drying minimizes or eliminates the effects of compression.

Log home companies fall into one of two categories regarding how they handle the possibility of settling.

Some companies simply ignore settling or declare it to be insignificant, which may be perfectly justified given the wood species they use, their drying method, construction techniques, and their experience. These companies make no special provisions for settling.

Other companies believe that settling deserves some attention, even if the possibility is slight. These companies may use a combination of springs on bolts, slip-mounted cabinets and trim, floating interior walls, jack screws, and settling space above doors and windows.

Which philosophy is correct? To be honest, it's not clear. To a large extent, we have to trust our chosen log home company to know their business and understand which philosophy works for them. However, it is our opinion that adding slip joints, floating walls, and settling spaces above doors and windows is very inexpensive insurance against the possibilty of problems in the future.

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