Minecraft wiki entry for Roof_types, associated text: A gambrel roof has two or three distinct roof pitches – steep lower down, and shallow or flat higher up. The result is that the usable volume under the roof is greatly increased. Some gambrel roofs may have one or more curved sections. If such a roof is partly curved and partly straight, it's usually the lower portions that are given curves first. These roofs would be hard to model well at normal Minecraft scales.