Fig. 113. - Plan of Valley in a Roof of Two Pitches.
To miter planceers and roof boards in valleys of two pitches it is only necessary to take the figures on the square which cut the bevels across the top of the jacks on the two pitches and reverse the cut, as the roof boards and planceers run in an opposite direction to the jacks.
The bevels may be taken from any plan showing the two pitches and cuts of jacks. Fig. 113 represents the plan of a valley in a roof of two pitches.
The dotted lines D B and B F are the lines plumb under the ridge. A B shows the run of the valley, C D the length of common rafter on left gable, and E F the length of common rafter on front gable. Transfer the length of common rafter C D to C G and draw the ridge line G H, which extends to the center of front gable. Transfer the length of common rafter E F to E I and draw the ridge line I J, which extends to the center of left gable. Connect A H and A J, which shows the position of valley for finding the bevels of the jacks, roof boards and plan-ceers on both sides of the hip. The bevels at K and L are the jack rafter bevels. The bevels at M and N are the bevels for mitering the roof boards or plan-ceers. The bevels at H and J are also the same as M and N, and show very plainly that they are the reverse of the jack rafter bevels. It is only necessary to have the planceers of a different width in order to have them member exactly, as will be seen by the boards in the diagram. If this plan is followed there will be no twisting of planceers in cornicing when joining roofs of different pitches.