Buttress

BUTTRESS. - Generic designation of a wall structure whose purpose is to counterbalance the thrusts in architectural organisms with vaults. Probably originating in Persian architecture (the oldest example being the palace of Fauruz Abid, perhaps of the 4th century B.C.), contreforts were also known to the Romans, who adopted them in bath buildings (the so-called temple of Minerva Medica, the Baths of Diocletian, where they take the form of towers).

In the centrally planned churches of Ravenna (S. Vitale) the contreforts appear as corner spurs. But the first basilical building in which they are adopted is presumably S. Babila in Milan (late 10th century), supporting the double arches that form the framework of the barrel vault. It should be noted, however, that attempts in this direction had already been made in the 9th century in some churches near Oviedo in Asturias.

Another important example from the 10th century is, in France, the church of St-Remi in Reims, in which they support the coverings both of the central nave and of the side aisles, thus constituting a double order of resisting structures.

But only when barrel vaults were definitively replaced by groin vaults for the covering of the naves did the contrefort come into common use in northern Italy, and in all of central and western Europe; it is often shaped in steps, or else terminates with columns that join onto the cornice, or finally is conceived in architectural form, as a pier or half-column for its entire height (late 12th century).

In this latter period they are also frequent in facades, to support the thrust of the dividing arches of the naves, especially in the Lombard churches, but also in those of Emilia and of Normandy.

In Gothic architecture the contreforts sometimes take the form of massive semi-cylindrical towers for the entire height of the building (S. Francesco in Assisi), or else resume the stepped form, but with a more varied profile; a subsequent refinement consists in separating the function of support in the lower zone from that of simple load-bearing in the upper part (cathedral of Séez), thus limiting the towers to the height of the springing of the vaults (cathedral of Orvieto).

The 14th century extends sculptural decoration to the contreforts as well, terminating them vertically with pinnacles and with statues, a practice that continues into the following century as well (cathedral of Milan, Certosa of Pavia). Generally, in Gothic churches with three naves, the contreforts are associated with the flying buttresses that carry back onto them the thrusts of the groin vaults of the central nave. Nevertheless, still in the full 15th century and up to the beginning of the following century, there are found in Rome (S. Agostino, S. ma Trinità dei Monti) contreforts consisting of solid walls, resolved in the latter century and in the 17th century much more rationally into large volutes, especially in churches with an elliptical plan (S. Giacomo in Augusta, S. Andrea al Quirinale, S. ma Annunziata of Parma, S. Maria della Salute in Venice), while the 18th century adopts robust towers for the same purpose (SS. Celso e Giuliano in Rome, sanctuary of Vicoforte).

Mario Zocca