Smaller Logs for Rafters
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].)
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.