Roofs and Gables 屋根と破風

Roofs (屋根)

There are 2 main roof types: Irimoya and Kirizuma. There are other types too but they are rarely if ever used for the main structures in castles.

Irimoya Roof (入母屋屋根)

In the Irimoya style roof there is a side of roofing that extends out and up from each side of the rectangular structure. Partway up two of the shorter opposite sides are stopped and the remaining two continue to the top where they are joined. The Irimoya style roof was also considered to be the most elegant and was used by the more upper class people for their homes. The top level of all extant and reconstructed castles has an irimoya style roof.

Kirizuma Roof (切妻屋根)

This is the simplest kind of roof. It is basically two sides joined at the top to cover the building. These are only rarely seen in castles except as the small roof that covers walls or the support pillars of koraimon gates. This construction is obviously simpler and cheaper to build so it was considered a lower class type of roof for homes. The kirizuma roof in the picture below is from the connected yagura of the main keep at Inuyama Castle.
Irimoya roofKirizuma roof
Matsumoto Castle Inuyama Castle

Gables (破風)

Gables (hafu) are the triangular decorations you see on castles and yagura. Besides the irimoyahafu of borogata tenshu, they are mostly decorative and often not necessary. Some later castles have done away with them completely.

Irimoyahafu (入母屋破風)

The sides of the gable are part of and indistinguishable from the roof. From the apex of the triangle down to the edge of the roof is one smooth side.
Kishiwada Castle Osaka Castle Himeji Castle Himeji Castle

Chidorihafu (千鳥破風)

This is the most common type of gable. The sides of the gable are joined at an angle to the roof. The edge of the gable is separated from the edge of the roof. It looks like it was attached to the outside of the structure as an after thought.
Matsumoto Castle Nagoya Castle Himeji Castle Kochi Castle

Kirizumahafu (切妻破風)

A kirizumahafu is similar to a chidorihafu, but the triangle only includes the two sides with no base. The bottom edge of the two sides of the gable is not connected to any roof.
Hikone Castle Hirosaki Castle Wakamatsu Castle

Hiyoku Chidorihafu / Hiyoku Irimoyahafu (比翼入母屋破風/比翼千鳥破風)

These two are just variations on the usual chidorihafu or irimoyahafu. It is where you have two chidorihafu/irimoyahafu on the same level. In the case of two irimoyahafu, only the outside edge is connected straight through with the roof of that level. Three chidorihafu in a triangular formation is also called kumi chidori hafu (組千鳥破風).
hiyoku irimoyahafuhiyoku chidorihafu
Himeji Castle Nagoya Castle Nagoya Castle Hiroshima Castle

Karahafu (唐破風)

A karahafu is similar to the kirizumahafu but the apex of the triangle is rounded and the sides are curved making it more decorative. It looks a bit like a recurve bow shape.
Inuyama Castle Matsumoto Castle Himeji Castle Nagoya Castle