Hiyodorisen

Hiyodorisen, known in English as trapezoidal through-tenons, is an advanced wooden joining method found in traditional Japanese architecture. With this technique, tapered trapezoidal tenons are cut through the full thickness of each beam end on the diagonal. Correspondingly shaped mortises are then chiseled through the complete depth of each vertical post. When fitted together, the diagonal grain of each tenon reinforces the perpendicular grain of the surrounding wood at the joint interface. Called hiyodorisen due to the distinctive "trapezoidal" shape of the tenons, this cross-grained connection provides maximum strength collectively across the joint. The layered reinforcement allowed structures like ceremonial halls and castle keeps to be built entirely from wood into sturdy, gravity-defying frameworks. Even now, remnants showcase hiyodorisen's role in engineering enduring architectural works through innovative grain-contravening joinery.