Early American log structures were characterized by relatively dark
interiors because window openings, designed for protective purposes,
were small and far apart. Since protection is no longer a consideration,
window frames may be of standard size and located where they are most
suitable for adequate day lighting.
As soon as the first round of logs and the floor joists are laid in
place, mark the location of door and window openings on the inside face.
Next saw out the door openings and chop out the notch in the doorsill log
to within an inch of the true or finished line, as shown in figure 13.
Leave final cutting of the openings to the exact dimensions until the
window and door frames are to be placed in position, thus insuring a good
finished wood surface. Also, determine the height of the openings above
the floor line and mark them in figures on the bottom log for reference
from time to time. The necessary cuts should be made in the log directly
over each opening before placing it in position. When the log which
carries the window frame is reached, a notch must be made for it as for
the doors.
[Illustration: Figure 13.--Cutting window and door openings.]
To provide the necessary doors and windows, openings must be cut in the
walls after the logs have been placed in position. As soon as a log in
the wall is cut in two, the problem arises of how to hold the loose ends
in place. Also, the doors and windows require the proper kind of frames
to insure airtight closure between the latter and the ends of the wall
logs. The most practicable and satisfactory method is to frame a vertical
notch in the ends of the wall logs, into which can be fitted a spline
attached to the back of the jamb or side-pieces of the door and window
frames. This method of framing holds the wall logs in place, allows them
to shrink and settle without hindrance, and makes a weathertight joint
between them and the door and window frames. The vertical notch in the
end of the wall logs may be framed by boring a 2-inch auger hole in each
log as it is laid in place. The hole should be located so that, when the
wall logs are sawed out for the opening, the saw cut passes down through
the edge of the hole nearest the opening. It is then a simple matter to
frame the notch to take the spline. The inside face of the notch can be
left rounded and the spline chamfered to fit. To keep the holes in line
from log to log, use the plumb board illustrated in figure 14.
[Illustration: Figure 14.--Method of marking openings.]