When round logs are laid up in a wall there is always an opening between
them unless they are grooved on the under side to saddle the one below,
as described later under chinkless log cabin construction. In exterior
walls, this opening, or crack, must be closed in order to make the
structure weathertight. There are several methods of doing this. If
the logs are reasonably straight and uniform in size and the corners
carefully made, the opening between them will be small, often barely
perceptible. When this is the case, the openings should be filled with
some sort of calking compound applied with either a pressure gun or a
trowel (fig. 24).
[Illustration: Figure 24.--Examples of tight joints well calked. _A_,
Interior calking; _B_, exterior calking.]
In recent years several kinds of calking material have been put on the
market. They are applied best with a gun having a pressure-release
trigger whereby the calking compound is forced through a nozzle made in
various shapes and sizes to meet different requirements. These calking
compounds are not adversely affected by heat or cold, retain their
natural flexibility, and have an adhesive property which causes them to
adhere to the surface to which they are applied.
A good plastic compound will adhere to the logs under all conditions
and can be patched easily by simply applying more material. A black
fiber seal is not objectionable and, at the same time, gives a practical
finish. The seal should be applied to both sides of the exterior and
interior log walls, producing an almost hermetically sealed building.
When applied with a pressure gun having a 3/8-inch nozzle, 1 gallon will
fill about 300 linear feet of opening. If applied in cold weather, the
material should be heated to a temperature of 60°F.