Yosemune-zukuri (寄棟造)
Yosemune-zukuri is a form of roof which has four sloping faces. In a broad sense, it also refers to buildings which have this type of roof. When referring to the style of roof itself it is often abbreviated to "yosemune". It is also called "shichu." In Japan it is the second most widely-used form after "kirizuma-zukuri" which has two sloping faces.
Summary
Yosemune-zukuri is a general form of roof for houses and other buildings throughout the world.
In Japan the form of roof which has an "omune" (horizontal section) at the highest point and has a rectangular flat form is generally called "yosemune-zukuri." Historically, it was more common in eastern Japan and was called "azumaya" in ancient times. Sometime during the Meiji Period, "hogyo-zukuri" (four-triangles-roof form) was confusingly also called by the same name.
Roof structure
The typical structure of a yosemune-zukuri roof has four sloping faces which consist of two triangle-shape roofs at "tsumagawa" (the side vertical to the omune) and two trapezoid-shape roofs at "hiragawa" (the side parallel to the omune). As yosemune-zukuri have four-way sloping roofs, the flow of rainwater drains well compared to the kirizuma-zukuri. However, as it has no vertical plane, it is likely to be badly ventilated compared to kirizuma-zukuri or irimoya-zukuri. Also, sometimes several yosemune are combined to form roofs of a complex shape.
Hogyo-zukuri
It is not possible to form an omune if you attempt to create a yosemune using square-shaped flat sections, as the four sections would need to be triangular. This particular kind of structure is called hogyo-zukuri (方形造, 宝形造). If this is a hexagonal shape, it is called rokuchu and if an octagon shape, hacchu.
Typical examples of this form of architecture
Toshodai-ji Temple Kondo (main building with a principal image of the temple)
Todai-ji Temple Daibutsu-den Hall (the Great Buddha hall)
Gango-ji Temple Gokuraku-bo Hondo