A gable roof features two sloping sides that come together at a ridge, resembling a triangle from the front and back. It is common in many architectural styles due to its simplicity and efficiency in shedding water and snow. A dormer roof is a structural element that protrudes from a sloping roof surface. A dormer roof can be used on gable, hip, flat, or shed roofs to increase the usable space in the loft area and add a window.