Minecraft wiki entry for Roof_decorations, associated text: To keep an inhabited building 'in scale', its roof should be in proportion with the building's other stories. Large featureless roofs tend to cover barns and hangars, and are rarely found covering dwellings. In practice, a good rule of thumb for roof height is to make it more than one story but less than two stories high. Hence with 4-meter stories, the roof should be in the range of 5–7 meters.