The wooden-shingle roof is of such old and traditional origin in this country that it seems useless to describe the essential features of its construction, yet for the sake of completeness we shall call attention to the important points to be observed. Cypress, cedar, and redwood are considered to be the best woods from which to saw shingles. The grain of the wood should be vertical and show the edge. It is generally conceded that creosote-dipped shingles which are treated at the factory are easier to apply than those dipped on the job, and, as all wood shingles should be treated with some preservative, it is well to consider them. However, much criticism has been aimed at factory-dipped shingles, in that they are generally too brittle from overdrying in the kilns, but this is not true of all makes. The sizes and the weathering of some of the standard creosoted shingles are as follows:
16 inches lengths, random widths, laid 4 1/2 inches to the weather, and either 5 or 6 shingles at the butt ends to 2 inches. 18 inches lengths, random widths, laid 5 1/2 inches to the weather, and 5 butt ends to 2 1/2 inches. 24 inches lengths, random widths, laid 7 1/2 inches to the weather, and 1/2 inch thick at the butt ends.
There are about thirty varieties of colored stains to select from, and special shapes are cut for constructing the so-called thatched roof, the shingles being bent to a curve of about 20 inches radius. The pitch of wooden-shingle roofs should not be less than 8 inches rise per foot for the ordinary weathering shown in the above statements. The tops of rafters are covered with shingle lath, with a spacing suitable to the weathering arrangement of the shingles. There are some who advocate the use of sheathing to cover the rafters in a tight manner and also the use of building paper underneath the shingles, but, although this gives a tighter and warmer roof, dry rot attacks the shingle much quicker because of the accumulation of dampness on the under side of the shingle courses.
The first course of shingles at the eaves should be a double course with the upper layer breaking joints with the lower, and the shingles should project about 2 inches beyond the mouldings of the eaves and about 1 1/2 inches beyond the edge of the gable ends of the roof.
Hips may be finished either with the saddle-board or with a row of shingles running parallel to the line of the ridge. Hips are best finished with a row of shingles running parallel with their edges, which treatment is called the Boston hip. If the courses are carried to the hip line and mitred, then the joint must be waterproofed by using tin shingles underneath the wooden ones, these tin shingles being folded over the hip. The method of flashing around chimneys, at the base of dormers, and in open valleys will be more fully discussed in connection with slate roofs, and, since the principles are the same, what is said for slate roofs in this connection is true for wooden-shingle roofs.