Which roof type is characterized by a V-shape with two sides sloping towards a valley?

The roof type characterized by a V-shape with two sides sloping towards a valley is called a butterfly roof. This design features two sloping roof sections that meet in the middle at a low point, creating a valley that is often used to collect rainwater. The butterfly roof is distinct for its unique convex or concave shape, resembling the wings of a butterfly. This form not only provides aesthetic appeal but can also be functional, facilitating water drainage and allowing for larger windows to let in more natural light.

In contrast, a gable roof has two sloping sides meeting at a ridge, forming a triangular shape at each end but does not feature a valley in the same manner. A flat roof is level or nearly level and does not have slopes directing water towards valleys. The gambrel roof, often seen in barns, has two slopes on each side but is more barn-like in style, not featuring the central valley typical of the butterfly design.