Lit. "a pole or rod." Aiso written 棹.
1 A lapped rod joint. The stacked tenon *jūhozo 重ほぞ is constructed with a long rod-shaped neck extending from a shallow lap or bench *koshikake 腰掛. This tenon is cut from the end of a beam. The stacked tenon is inserted into a mortise *hozoana ほぞ穴 on another beam shaped to receive it. Keys *shachi 車知 are often added to strengthen the joint. See *saobiki dokko 竿引独鈷, *shakuzue 尺杖, *saobuchi tenjō 竿縁天井, *saoshachitsugi 竿車知継.
2 A straight structural member, such as the ridge, saomune竿棟, used in a vernacular dwelling *minka 民家, especially in Saga Prefecture.
3 The shaft of a stone lantern ishidōrō 石灯籠. The sao is set on a base and supports all the upper parts of the lantern including the fire box. See *tōrō 灯籠.