interarch

Interarch is a term used in architecture and structural engineering to denote the space and relationship between adjacent arches or arch openings in a structure. It encompasses the horizontal spacing, measured between spring lines or centers of arches, and the vertical alignment of elements such as impost blocks and voussoirs within a continuous arcade or series of openings. The interarch rhythm—the repetition and proportion of arches—contributes to both the aesthetic character and the structural logic of a design.

In masonry and arch construction, the interarch clearances influence how load is transferred from the arch ring to supporting piers and spandrel panels. Consistent interarch dimensions help maintain even mortar joints and a uniform keystone distribution, while variations in interarch width can alter thrust distribution and visual mass along a façade or arcade.

Interarch relationships are important in the planning of bridges, viaducts, cloisters, and facades. Architects use predictable interarch spacing to create rhythmic patterns that align with other architectural elements such as windows, doors, and column bays. In historic contexts, regular interarches are a common feature of Roman, Byzantine, and Gothic arcades, where the cadence of arches governs both functionality and ornament.

In contemporary practice, interarch considerations continue to influence modular and prefabricated designs, where standardized arch spans allow rapid construction while maintaining structural integrity and architectural harmony.