Which roof type has sloping planes of the same pitch on each side of the ridge?

The gable roof is characterized by its two sloping planes that meet at a central ridge, creating a triangular shape at each end. This design not only provides an aesthetically pleasing look but also facilitates effective water runoff, which is crucial in preventing water accumulation and potential leaks. The symmetry of a gable roof, where both sides have the same pitch, enhances its structural integrity and allows for easier ventilation in the attic space, contributing to better airflow and temperature regulation.

In contrast, a flat roof presents a horizontal surface rather than sloping planes, which can lead to drainage challenges. A hip roof, while also sloping, has planes that meet at the ridge but features a more complex geometry with slopes on all four sides, creating a different visual and functional profile. Lastly, a mansard roof consists of two slopes on each side, with the lower pitch being steeper than the upper, resulting in a more intricate design aimed at maximizing usable attic space.

Thus, the gable roof's distinct sloping planes of equal pitch reflect its defined characteristics, making it the correct identification in this context.