Paragraph 77. A quarter-pitch roof is one in which the elevation of the rafters is one-fourth the width of the building. To illustrate: if the width of the building is 24 ft., the elevation of a quarter-pitch roof will be one-fourth of 24, which is 6 ft. This cut for a rafter would be laid out as indicated in Chapter 2, Paragraph 26.

Of course in roof construction there are a great many other rafter problems which arise, such as the cutting of valley, hip and jack rafters.

As this information belongs purely to the carpenter's trade, it is not worth while taking it up here. The matter of getting the length of rafters is a simple problem which can be easily figured out in the arithmetic class by figuring the hypotenuse of a right triangle, in which the elevation is the altitude and one-half the width of the building is the base. Of course the carpenter has rules by which he is able to get the length of a rafter by the use of the steel square.

Figure 62.