Roofs may be framed in several ways, depending upon the kind of material
available and the appearance desired. The framing for a shingle roof,
whether of sawed material or round poles, is done in the same way as that
of a frame building. The top log on the wall may be cut with a flat seat
for the rafters to rest upon, as at _Y_, in figure 18, _A_ or notched out
to receive them as at _Z_ in figure 18, _B_. The gable ends may be run
up with the logs, which is preferable for architectural appearance, or
framed like the gables of a frame structure, and then covered with wood
siding, shingles, or shakes (fig. 19).
The shingles may be laid over sheathing boards in the usual manner or on
shingle strips placed across the roof rafters, parallel with the ridge
and exactly spaced to receive them, commonly known as "barn-fashion."
The particular method to be followed in framing the eaves depends largely
upon their projection. Where the effect of a considerable overhang is
desired, an eave purlin log may be used to support the projecting shakes
as shown in figure 19, _A_. To support 30- to 36-inch long shakes having
a 6-inch lap, the log purlins should be spaced at approximately 24-inch
intervals, as in figure 19. In regions of heavy snows, the eave log may
be placed slightly forward to help support the overhang, or an additional
eave log may be placed in position, as shown in figure 19, _B_. The gable
logs should be run up at the same time as the roof logs, and both rigidly
framed together.
[Illustration: Figure 20.--Splitting shakes with the froe.]