Which rafter forms the intersection of an internal roof angle?

The valley rafter is the correct choice because it specifically serves to form the intersection at internal roof angles, where two sloping roof sections meet. This type of rafter is critical in areas where the roof’s design creates a valley, allowing for proper drainage of rainwater and ensuring structural integrity.

In contrast, the hip rafter runs diagonally from the ridge to the eaves and supports the ends of the roof, contributing to the overall shape rather than creating an internal angle. The common rafter supports the roof between the ridge and the wall plate but does not participate in forming the internal angles of a roof structure. The ridge rafter, on the other hand, is the horizontal support that runs along the peak of the roof, providing a framework for the common rafters but is not involved in forming the internal angles of the roof. Thus, the valley rafter is essential for intersections where different sections of roofs come together, making it the right answer.