balaustra

Balaustra, in architecture commonly referred to as balustrade, is a railing formed by a series of small columns, or balusters, supporting an upper handrail and often a lower rail or base. The arrangement creates a barrier along stairs, landings, balconies, terraces, or rooftops, while allowing light and visibility. A typical balaustra consists of vertical balusters, a continuous top rail, and sometimes a bottom rail; the ends are anchored by newel posts.

Etymology and history: The term derives from Italian balaustra (or balaustrata) and from balaustro, related to the vase-like shape of many early balusters; the concept was developed in classical architecture and flourished in Renaissance and Baroque periods.

Materials and forms: Balustrades have been executed in stone, marble, wood, cast or wrought metal, and modern uses include concrete and glass. Balusters are frequently turned or moulded; in classical styles they are often bulbous or vase-shaped, while later neoclassical and modern designs favor simpler, straight forms or minimal metal.

Construction and safety: Balustrades function as safety barriers and as architectural decoration. Modern codes regulate baluster spacing to prevent large openings and ensure load-bearing performance; common limits specify a maximum gap of about 4 inches (10 cm) between balusters or around the barrier openings.

See also: railing, parapet, architectural ornament.