A rib vault, also called a ribbed vault, is an architectural feature for covering a wide space, such as a church nave, composed of a framework of crossed or diagonal arched ribs. Thin stone panels (called severies or webbing) fill the space between the ribs. This greatly reduced the weight and thus the outward thrust of the vault compared to earlier vaulting systems. The ribs transmit the load downward and outward to specific points, usually rows of columns or piers. This feature allowed architects of Gothic cathedrals to make higher and thinner walls and much larger windows.
Structure and Function
A rib vault is a type of arcuated (arched) vault in which the severies (panels in the bays of the vault's underside) are separated from one another by ribs that conceal the groins (the intersections of the panels). Rib vaults are, like groin vaults, formed from two or three intersecting barrel vaults; the ribs conceal the junction of the vaults. The ribs form the main structural lines, while the thinner masonry webbing fills the spaces between them. Instead of one heavy continuous shell doing all the work, the vault is organized into a skeleton-and-infill system. The load path moves from the webbing to the ribs, then down through the springing points into piers or columns below.
Early History
The first known rib vaults were built by the ancient Romans in the 2nd century AD. An early example is documented in the Villa of the Sette Bassi in Rome, dating from the mid-second century AD. In these Roman vaults, brick ribs were embedded into the concrete of the vault, unlike later Gothic vaults where the ribs were separate from the infilling panels.
In the medieval period, the earliest surviving example in Islamic architecture is at the Mosque–Cathedral of Córdoba in al-Andalus (begun in the 9th century and extended between 922 and 965), which predates the earliest Romanesque examples by about a century. The crossed-arch vaults of Córdoba served as models for later mosque buildings in the Islamic West, including al-Andalus and the Maghreb.
Rib vaults were not common in Byzantine masonry buildings, though four ribbed vaults were built at the Hosios Loukas monastery in Byzantine Greece after 1000 AD.
Romanesque Architecture
The rib vault was developed further in northern Europe in the 11th century as builders sought to construct larger stone vaults to replace the wooden roofs of Romanesque churches, which were frequently destroyed by fire. Romanesque cathedrals and churches usually used the barrel vault (with rounded arches) and the groin vault (used when two vaults met at a right angle). The weight of these vaults pressed down directly onto the walls, requiring thicker walls and smaller windows.
The Kingdom of England and the Duchy of Normandy became centers of architectural innovation in the late 11th century. Construction of Durham Cathedral began in 1093, and its nave vaults, with pointed arches, were begun around 1130. The space between the ribs was filled with severies made of small pieces of stone. At its corners, the weight was supported by colonettes that transferred it downward to alternating columns and piers below rather than to the walls.
Gothic Architecture and the Pointed Arch
An alternative to barrel vaults in the naves of churches, rib vaults in 12th-century early Gothic architecture began to be used with pointed arches, already known in the Romanesque style. Thanks to the pointed arch, builders could raise or lower the arches so they would have the same height for a short span or a long span, something not possible with round arches. Pointed arches also made two intersecting vaults of the same height but different widths easier to construct.
Sexpartite Vaulting
In sexpartite vaulting, each bay was divided by thin stone ribs into six compartments. The intermediate ribs diagonally crossing the vault formed a pointed arch, with an additional intermediate pointed arch crossing from side to side. The first cathedral to use sexpartite vaults was Durham Cathedral (begun 1093). The system appeared in Noyon Cathedral (begun 1131), Sens Cathedral (begun 1135), the choir of the Abbey of Saint-Denis (begun 1140), and Notre-Dame de Paris (begun 1163).
Quadripartite Vaulting
A new variation appeared during the High Gothic period: the four-part (quadripartite) rib vault, used in Chartres Cathedral, Amiens Cathedral, and Reims Cathedral. The ribs of this vault distributed the weight more equally to the four supporting piers below, allowing for greater height and thinner walls. Amiens Cathedral (built 1220–1266), with four-part rib vaults, has a nave 138.8 feet (42.3 meters) high.
Complex Rib Vaults
Beginning in England with the Decorated Gothic style of the late 13th century, a variety of complex vaults emerged incorporating purely decorative ribs in addition to structural ones. These include:
- Tierceron vaults: Use tertiary ribs (tiercerons) in addition to the main structural ribs.
- Lierne vaults: Feature short decorative ribs (liernes) that connect one rib to another, creating intricate star, web, or net patterns.
- Fan vaults: A unique type particular to England, where all ribs are of the same curve and spaced equidistantly, resembling a fan. The earliest example is in the cloisters of Gloucester Cathedral. King's College Chapel, Cambridge, has the world's largest fan-vaulted ceiling.
Construction
The first step in constructing a vault was a wooden scaffold up to the level of the top of the supporting columns. A precise wooden frame was constructed on top of the scaffold in the exact shape of the ribs. The stone segments of the ribs were carefully laid into the frame and joined with mortar. When the ribs were all in place, the keystone was placed at the apex where they converged. Once the keystone was in place, the ribs could stand alone, supported by their weight pressing downwards and outwards. Workers then filled in the compartments between the ribs with small fitted pieces of brick or stone. The masonry of the compartments was about 15 cm thick. Once finished, the interior surface was plastered and painted.
