The Probert Encyclopaedia of Architecture

VAULT

In architecture, a vault is literally an arched roof. The term is also used for a chamber with such a roof and, as these are often underground, it has come to be used for cellars where wine is stored.
Architecturally, the earliest form was the barrel vault, shaped like the upper section of a railway tunnel. This was invented by the Persians, and employed later by the Romans, who discovered how to construct the groined vault by intersecting two barrel vaults at right angles to each other, the groin being the angle formed by the meeting of the two surfaces. The groined vault was used in Norman building until the introduction of the ribbed vault.

In the groined vault the solid construction required a great weight of masonry, which had to be carried by a proportionately heavy supporting wall. The ribbed vault was constructed by means of a series of narrow stone arches crossing each other diagonally, and so forming a framework for the arch, the intervening spaces being then filled up with comparatively light webbing, so as to complete the roof. During the 13th century the number of ribs was increased; in the 14th century important modifications were made in their curvature, and in the 15th the pitch of the vault, was reduced, and the ribs again grew more numerous, and the spaces between them narrower. This led to the introduction of cross ribs to divide their length, and to the formation of what is called lierne vaulting, whence sprang the fan-tracery vaulting, the climax of Gothic vaulting skill.
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