Cornerstone - Soseki

These stones are placed at the foundations of buildings to transfer the weight of the building to the ground, preventing the pillars and foundations from directly touching the ground and corroding. It is said to be a technique that was introduced along with Buddhist architecture during the Asuka period. The use of cornerstones dramatically extends the lifespan of a building, but unlike post-hole buildings, the pillars do not stand on their own, so cornerstone construction requires the development of architectural structures and construction techniques such as frame construction. In the Nara period, cornerstones were used in temple construction such as the Golden Hall of Horyuji Temple and government buildings in Heijo-kyo. In the Heian period, cornerstone construction began to be used in residential construction such as shinden-zukuri, and in buildings for castles in the provinces. In the Kamakura period, cornerstones were used in the sobashira buildings used for high-ranking samurai houses and in the homes of local lords during the Muromachi period, such as the boxwood millennium houses, but it was during the Edo period that commoner homes and other buildings switched to cornerstone construction. When natural stones are used as foundation stones, a technique called "hikari-tsuke" is used to cut the base of the pillar to match the curved surface of the stone to prevent misalignment between the pillar and the foundation stone. There are also foundation stones with flattened tops, foundation stones with tenons or tenon holes, and foundation stones with drainage grooves. The core stone of a tower is a type of foundation stone placed underground.

[Nanae Nakao]

"Detailed Designs of Ancient Architecture by Yutaka Kondo (1972, Taiga Publishing)" ▽ "Buried Medieval and Early Modern Residences edited by Shigeo Asakawa and Kazuhisa Hakozaki (2001, Doseisha)" ▽ "Kyoto City Archaeological Research Institute Excavation Report 2008-22 Heian-kyo Ukyo Rokujo 1-bo Jyunchō Site" (2009, Kyoto City Archaeological Research Institute)

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

建造物の基礎に据えられ、建物の重量を地面に伝える石材で、柱や土台が直接地面に触れて腐食劣化するのを防ぐ。飛鳥時代に仏教建築とともに移入された技術とされる。礎石を用いることで建物の耐用年限は飛躍的に延びるが、掘立柱建物と異なり、柱が自立しないため、礎石建ては軸組構造(じくぐみこうぞう)など建築構造や施工技術の発達が不可欠である。奈良時代には礎石は法隆寺金堂などの寺院建築や、平城京の官衙建物に用いられた。平安時代には寝殿造などの住宅建築や、地方の城柵の建物にも礎石建てが行われるようになった。鎌倉時代の鎌倉では上級武士住宅に用いられた総柱建物(そうばしらたてもの)や箱木千年(はこぎせんねん)家など室町時代の土豪住居で礎石が使われたが、民家などの庶民住居が礎石建てに転換したのは江戸時代である。礎石は自然石をそのまま用いる場合、柱底を石の曲面に合わせて削る「ひかりつけ」という技法を用いて柱と礎石のズレを防ぐ。また上面の柱当りを平らに加工した礎石や、ホゾ（枘）を造り出したり逆にホゾ（枘）穴を穿った礎石、水抜き溝を切った礎石などがある。塔の心礎(しんそ)は地下に据えられた礎石の一種である。

［中尾七重］

『近藤豊著『古建築の細部意匠』（1972・大河出版）』▽『浅川滋男・箱崎和久編『埋もれた中近世の住まい』（2001・同成社）』▽『『京都市埋蔵文化財研究所発掘調査報告　2008―22平安京右京六条一坊十四町跡』（2009・財団法人京都市埋蔵文化財研究所）』

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