VAULT. - A roof wall structure, shaped in view according to a curved surface, and exerting a thrusting action on its supports (piers); within it one distinguishes the lower surface, visible from inside the room, called the intrados, and the upper one, mostly hidden by the roof or by the floor of the room above, called the extrados.
On the basis of the shape of the intrados, vaults are classified into various types, of which the main ones are: barrel, mostly adopted in rectangular rooms, consisting of a cylindrical surface whose generatrices are normally parallel to the longer side, and whose directrix (that is, the normal section) may be semicircular, or a segmental arch, or a basket-handle or polycentric arch; groin, adopted instead for rooms close to square, consisting of the intersection of two cylindrical barrel vaults, so that the walls are met along the directrices; cloister, formed by the intersection of two vaults as above, but with the walls meeting along the generatrices, so as to be complementary to the preceding one; a schifo, that is, a cloister vault truncated at the top by a horizontal plane; sail; a catino, consisting of a spherical calotte.
The vault originates from the need to cover large spaces by means of small elements easy to obtain or to make on site; this explains how it arose in the countries of the Middle East, poor in timber and in cut stone. The Romans learned its construction from the Etruscans and then made it the typical structure of their architecture, from which it was inherited in Christian places of worship. As materials were employed: brick, sometimes in special shapes, better suited for execution; cut stone in blocks suitably shaped in order to take account of the obliquity of the joints; finally, light materials (e.g., in Byzantine architecture [v. BIZANTINA. ARTE] special vessels to reduce the weight; plaster and similar materials in the eighteenth century, when the vault had a more decorative than structural function).
In religious architecture the vault has represented one of the determining elements of stylistic forms in all epochs, both because it influenced the iconography through the conformation and the spacing of the pier structures, and because it contributed to giving a special appearance to the interior of churches, especially as vertical development.
Early Christian architecture generally did not make use of the vault, preferring in basilicas the covering with an exposed roof; there are nevertheless examples of annular vaults, that is, barrel vaults with circular rather than straight generatrices, adopted
VOLPICELLI, CATERINA, venerable. Portrait.
in the space surrounding the central part — mostly covered by a dome — of baptisteries and other similar buildings (St. Constance in Rome).
Later, toward the 11th century, the use of the barrel vault begins to be taken up again, generally limited to some chapel (of St. Silvester in the SS. Quattro in Rome, of the Assumption in St. Mary infra portas at Foligno), but sometimes adopted for the covering of the entire building, especially in Umbria (St. Peter of Bovara, S.
Silvester of Bevagna, St. Juvenal of Orvieto; in these last two churches the side aisles are covered with half-barrel vaults) and more rarely in southern Italy (St. Margaret of Bisceglie), probably through Eastern influences. Less frequently than in some countries beyond the Alps are there reinforcing arches (arcs doubleaux) placed at more or less regular intervals with the aim of concentrating the thrusts at suitable points, when the supporting structures are discontinuous.
It is precisely these latter considerations that determine the invention of the groin vault, at first employed only in crypts (St. Eusebius of Pavia, St. Peter of Tuscania, St. Vincent al Prato of Milan), then in the nave, but associated with other systems (with the dome in St. Babila of Milan, with the barrel vault in SS. Maria and Sigismondo of Rivolta d'Adda) and finally alone (among the earliest examples, St. Ambrose of Milan), this latter form becoming frequent already in the second half of the 11th century. The main nave is then divided into regular intervals (bays) in the longitudinal direction in order to obtain square or nearly square spaces; and for the same purpose the number of bays in the side aisles is doubled, making two correspond to each one of the main nave; with the groin vault the type of the Lombard church thus takes shape, which would spread beyond the Alps as well.
A further refinement was introduced, again for the same purpose, in the last years of the same century with the introduction of ribs (v.); the need to connect them with the supporting structures led to replacing columns with the pier consisting of a pillar to which clusters of small columns are applied; finally the raising of the vault was adopted, so that the diagonal arches, originally elliptical, became circular and in some cases even pointed. These arrangements, which appear sporadically in Italy already during the 12th century (cathedrals of Modena and Parma), then became fully widespread in the following century, especially with Cistercian architecture (v.). In the Renaissance the groin vault still finds some limited application (St. Mary of the People in Rome), but with the suppression of the ribs, thus simplifying also the conformation of the supports; but the prevailing form — when a flat ceiling is not adopted — is the barrel vault, more in keeping with the new classical feeling (abbey of Fiesole, St. Andrew of Mantua, St. Sixtus of Piacenza). In the 16th century it would become the usual form of covering, transformed into the lunetted barrel vault (by means of the intersection of cylindrical vaults of lesser rise), which allows windows to be opened above the side chapels to light the nave, and at the same time to accentuate the rhythm of the bays (St. Mary of the Mount and the Gesù in Rome, the Redentore in Venice, etc.).
In the 17th century, however, and even more so in the 18th, Baroque conceptions, especially those of Borromini, aimed at replacing the simple Latin cross with more complex iconographies, are also reflected in the conformation of the type of covering, which no longer arises from the intersection of elementary geometric forms, but from the interpenetration of spheroid and ellipsoid solids, which finds expression in the complicated interweaving of ribs in different directions. Such arrangements would be adopted especially in churches of Piedmont by Juvara, Guarini and Vittone, then spreading abroad and particularly in Germany and Austria, where in a certain sense they would link up with the tradition of the stellar vaults of the late Gothic period, which however found no applications in Italy at that time.
During the Neoclassical period, alongside the frequent use of the flat ceiling, the simple barrel vault would be taken up again and then continued throughout the 19th century.
Contemporary architecture, availing itself of the vast possibilities offered by reinforced concrete, has produced new forms based on concepts different from the traditional ones, that is, the so-called thin vaults of various types, of which there are examples in the new churches of Pisa, Recoaro, Francavilla al Mare, and Milan, arising from the competitions announced by the Pontifical Commission for Sacred Art, which have promoted the study of new solutions interesting from the constructive and the aesthetic standpoint.
The decoration of vaults follows the vicissitudes of taste and of artistic conditions in the various epochs. During the Early Christian period it is entrusted predominantly to mosaic, in the Romanesque and especially in the Gothic period to fresco, particularly through great pictorial cycles. In the Renaissance it is generally decorated with coffers of classical inspiration (St. Andrew of Mantua) or with paneled ceilings that follow the same motifs as the flat ceiling (sacristy of St. Spirit in Florence). In the second half of the 16th century, however, the use of fresco is taken up again, but in the form of great pictorial compositions (mostly glories of saints), to which the continuity of surface of the barrel vault lends itself well; later stucco and gilding are associated with the painting. The 18th century, on the other hand, prefers greater simplicity and reduces decorative richness, giving predominance to white stucco.