This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
A very interesting form of gable roof is that in which there is a double gable with a valley between, which forms the roof of an ell when the main roof is a simple pitch roof. This form of roof is shown in Fig. 183. Fig. 184 shows how such a roof may be framed. The piece A is placed in the wall and supported by the studding so as to serve as a plate to receive the ends of the valley rafters B. These, together with the piece C, form the framing for the shallow valley between the two gables. The valley rafters on the outside, marked D in the figure, are similar to those used in the case of a single gable. The pieces E E are jack rafters and are very short. This form of roof is not common, but in some places it gives a good effect.