koana 小穴
KEY WORD : architecture / general terms
A shallow, narrow groove cut into a pillar, flooring board or other structural element to allow for a secure junction with other members. This operation utilizes a type of angle called *shiguchi 仕口. The board to be inserted has a right angle piece cut out of it, similar to a shiplap joint *aijakuri 合决 except in this case the extending part is set into a groove in an upright position rather than broadside down as flooring boards would be. Several expressions are used to refer to the actual boring of the narrow groove: koana-ni-shiguchi 小穴に仕口, which means to join the member by placing it at right angles into the narrow groove; koana-ni-ire 小穴に入れ has the same meaning; and koana-ni-tsuki 小穴に突き, means to bore a narrow groove. When a koana is used for a plastered wall, it is called chirijakuri 散决.

a) koana 小穴 b) habaki 幅木 c) yuka-ita 床板


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