There are two ways of making window and door frames—in three pieces (two side jambs and one head jamb), or in four pieces (two side jambs, one head jamb, and a sill piece). When a three-piece frame is used, the bottom log of the opening is cut or shaped to make the window or doorsill and the jamb pieces are then fitted to the sill. If the jambs are framed from pieces of log slabbed on two opposite sides, a presentable frame in keeping with the log character of the structure is obtained. The window or door face of the jamb pieces may be rabbeted for the windows and doors, respectively, or they may have separate wooden pieces, known as stops, nailed on. The spline on the back of the jamb may be rabbeted out, or a 2 inch by 2 inch piece of straight-grained wood nailed on. The head jamb can be framed in the same way; it does not require a spline on the back. Each side jamb has a dowel framed on each end. The bottom dowel fits into a mortise in the sill and the top dowel into a similar mortise in the head jamb.
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Figure 15.—Window frames.