saobuchi tenjō 竿縁天井

Also written 棹縁天井. A board and batten ceiling. A simple ceiling made of light weight boards laid in one direction over regularly spaced battens *saobuchi 竿縁, placed at a right angle to the boards. The battens are usually spaced 30 to 40 cm apart and made of cypress, cedar, bamboo or occasionally of small, unstripped red pine or cherry branches. Perhaps the earliest use was in monks' dwellings *sōbō 僧房, of the 7th-8th century. It was also used in ordinary dwellings, jūtaku 住宅, and sometimes even used in formal rooms *zashiki 座敷. In temple buildings the board and batten ceiling is usually found in the aisles *hisashi 廂, in sections of the core *moya 母屋, and in the worship area *raidō 礼堂. In *sukiya 数奇屋 style buildings that incorporated features of tea ceremony houses, the battens are often left in a natural, rough condition. In the formal shoin style *shoin-zukuri 書院造, the corner edges are carefully squared. Viewed in cross section, the ceiling reveals several distinctive details. Sarubōmen 猿頬面, a batten with six-sided chamfers, was used from the Kamakura period onward. A simple type of batten, hirabuchi 平縁, is typified by a flat rectangular cut. Other battens are chamfered at a 45 degree angle *kirimen 切面. To prevent sagging of the boards or the appearance of gaps, small slip fasteners *inago 稲子, were attached to the reverse sides. Slip fasteners were unnecessary if the boards were secured by scarf joints *sogitsugi 殺継.