The length of the valley rafters is based on the run of the common rafters that have their upper (ridge) ends at the same level as the valley rafter.

Question

Quizplus · Accepted Answer

The length of the valley rafters is indeed based on the run of the common rafters, as the valley rafter must span from the eave to the point where it intersects with the ridge, which is determined by the layout and length of the common rafters that reach the same ridge level.

The Length of the Valley Rafters Is Based on the Run