corbeling

Corbeling is a traditional masonry and timber construction technique in which successive courses project beyond the one below, creating a cantilever. When these projections are paired and spaced properly, they can form features such as a corbel arch, a corbel vault, a corbel table, or a projecting parapet.

In general, each new course is set slightly farther inward, transferring weight to the supporting wall and enabling the upper structure to be supported by a stepped stack of blocks rather than by a true arch. A corbel arch is built by cantilevering stone or brick until the courses meet at the center, creating an arch without voussoirs.

Common applications include corbel tables (a series of projecting blocks that support a cornice or parapet), machicolations (spaces between corbels that allow objects to be dropped on attackers), and corbel vaults, where intersecting corbel systems generate a vault. Corbels can be made of stone, brick, or timber, and may be purely decorative or functionally load-bearing.

Corbeling appears in many ancient and medieval architectures around the world. It is prominent in Mycenaean and early medieval European buildings, where it was used to fashion ceilings, vaults, and external cornices. In fortifications, corbels often supported parapets and defensive machicolations.

Compared with true arches, corbeling is generally less material-efficient and relies on gravity and design to transfer loads. It remains an important historical technique and continues to be used today in restoration work and in architectural styles that seek rustic or fortress-like expressions.