Minecraft wiki entry for Roof_types, associated text: A dormer is a structural element of a building that protrudes from the sloping plane of the roof. (C.f. monitor, which straddles a roof ridge.) Dormers create extra space in the roof by adding headroom, and they allow the addition of dormer windows. Dormers have their own 'mini-roofs' above them, and these can have almost as wide a variety of roof types on them as the buildings themselves, theoretically even including curved roofs.