Rafters are the next problem. Choose smaller timbers, yet ones that are
well proportioned to the purlins. For the average cabin, logs with
four-inch butts are about right. They should be spaced not more than two
feet on the centers. Saw a square cut into the plate log—the top logs of
your walls—then square a place on your rafter to fit into this cut.
Drive it well home. (Fig. 9.)
[Illustration: Fig. 8]
FIRST LOG OF SIDE WALL, NOTCHED TO FIT OVER JOIST
JOIST FLATTENED VERY SLIGHTLY
SILL, HEWN FLAT ON TOP
FOUNDATION
GAIN
TENON
Each rafter should be cut in slightly to the purlins and spiked tightly
to each purlin and to the ridge log. When setting in any of these pieces
don’t forget to bed them well with oakum to make sure that they are
weather tight. Dressed siding is good material for the roof. On this
nail the roofing you have selected.
The type of roofing used depends on how much you want to spend.
Composition roofing is fire resistant and will last quite well, but it
is not particularly attractive on a log cabin. Shingles laid in the
customary way with the butt ends exposed for about one-third of the
length make a good roof. Shakes probably make the most interesting as
well as durable roofs for a cabin, although they are more expensive.
Shakes come in various sizes and add a final distinctive touch to a
house.
If you expect to use your cabin in very cold weather, a double roof
would be the wise provision. After laying your sheathing, cover it with
a layer of building paper or other insulating material. Then nail on a
series of 2×2 timber strips parallel to the rafters beneath. Across
these strips lay another layer of sheathing and then the shingles or
shakes. This forms a dead air space that is effective in insulating the
house against cold.