Shihouari

Shihouari, commonly referred to in English as four-sided mortise and tenon joints, involves complex interlocking joinery utilized in pre-modern Japanese architecture. In shihouari construction, the end of each beam is fitted with a long tenon extending out from all four faces of the squared off end. Corresponding mortises are then precisely chiseled into the four faces of each upright post the beam will connect to. When fitted together, the four tenons on the beam are inserted simultaneously into the post's four mortises, joining the horizontal and vertical members so their wood grains intersect at right angles. This created an extremely robust bond, as the opposing grain directions reinforced one another. The multi-planar cross-grained shihouari joint permitted sturdy construction of architectural frameworks like temples and castles, enabling resilient load-bearing without need for mechanical fasteners.