Voussoirs

Voussoirs are wedge-shaped stones, bricks, or blocks that form the components of an arch or vault. Each voussoir is cut so that its inner edge follows the arch curve while its outer faces reflect the intended profile, creating a ring-like segment. When arranged from the spring line toward the crown and bound by the keystone, the voussoirs distribute weight through compression and transfer loads to the supports.

Structural function and arrangement: the individual elements are shaped so that the forces are directed along their faces toward the abutments, reducing bending moments. The keystone at the arch’s apex locks the assembly in place, completing the ring. The first stones at the base are known as springers, and the stones near the crown can be referred to as crown voussoirs. Arches can be semicircular, segmental, or pointed, each requiring corresponding voussoir geometry to maintain a stable thrust distribution.

Overview and history: The term voussoir derives from French, related to voûte meaning vault, and denotes the wedge-shaped units used to form arches and vaults. Voussoirs have been a fundamental element of masonry since antiquity, prominent in Roman arches and later in medieval Romanesque and Gothic architecture. In modern practice, they may be cut from stone, brick, or concrete and used as either traditional hand-cut components or prefabricated units for rapid construction and restoration projects.