Forms of vaults
There are a great many forms of vault. The simplest are barrel vaults which in fact consist of a succession of identical arches. Barrel vaults can have steeper or nether profiles: semicircular, segmental, ogival. etc. The catenary vault is very common as its form gives maximum stability for a minimum use of material.
Combining two barrel vaults with the same profile allows two other types to be defined: the "groined vault" and the "Dominica! vault". By prolonging one of the two barrel vaults, the "Dominica! vault" becomes a "trough vault". Combining barrel vaults with different profiles forms a "lunette vault".
A "Dominica! vault", the ribs of which are rounded in the form of cones starting from the corners, becomes a "squinch vault". Similarly the "trough vault" can evolve into a "boat vault".