Vault

A vault is a curved covering created by continuing the logic of an arch along an axis. In section it behaves like an arch, carrying its load in compression, which allows wide spaces to be roofed in stone or brick without beams. Vaults are common in cellars, cisterns, under bridges, in bathhouses and over the naves of churches.

Types of vault

The simplest form is the barrel vault: a half-cylinder resting continuously on two parallel walls. Where two barrel vaults cross at right angles, a groin vault is formed; the load gathers at four corner points and the walls between can be opened up. Gothic builders emphasised those intersecting lines with stone ribs, giving the rib vault. Like a dome, a vault pushes outwards at its base, and that thrust is resisted by thick walls, buttresses, neighbouring vaults or iron tie rods. If it is not resisted, a vault can spread and collapse. In contemporary architecture, vaulted forms reappear as thin concrete shells, glulam timber arches and brick shells.

Modelling a vault

In vaulted spaces, light spreads in a soft gradient across the curved surface. To capture that in a render, the curve needs to be modelled smoothly enough, and brick or stone textures must follow the surface in the right direction without breaks. In groin vaults, keeping the intersection lines crisp is what makes the space readable.