Vault (architecture)

In architecture, a vault is a self-supporting arched form. It is usually constructed from stone or brick. Its primary purpose is to cover a space with a ceiling or a roof.

To build a vault, architects must manage gravity and weight. During construction, a temporary support is required. This support holds the individual pieces in place. These pieces are called voussoirs. Builders often use a framed truss known as centering. Centering typically has a semicircular or segmental head. The vault remains unstable until the very last piece is placed. This topmost stone is called the keystone. Once the keystone is in position, the structure becomes self-supporting.

There are several distinct ways to construct these curved ceilings. The simplest form is the barrel vault. A barrel vault has a semicircular cross-section. It resembles a long tunnel or a barrel cut in half.

Another method is the pitched-brick vault. In this technique, bricks are installed vertically rather than radially. The bricks lean, or are pitched, against an existing wall. This method allows builders to complete the vault without using centering.

A more complex form is the groin vault. This is created when two barrel vaults intersect at a right angle. The intersection creates lines called groins. These groins mark the transition between the different surfaces of the vault.

Advanced builders also developed the rib vault. This type of vault uses diagonal ribs in the form of segmental arches. In a rib vault, the builders set up the diagonal ribs first. These ribs act as permanent centers for the rest of the structure. The rest of the vault, or the web, is then built upon these ribs. This method revolutionized construction. It was a major change from earlier systems. Previously, builders had to manage difficult elliptical curves. The rib vault allowed for more efficient and stable designs.

History shows that vaulting has been used for thousands of years. The Mycenaeans used conical vaults for tholos tombs between 1800 and 1050 BC.

These are often called beehive tombs. In the Neolithic village of Khirokitia on Cyprus, builders used mud-brick corbel vaults. These structures even provided evidence for settlements with upper floors. In Egypt, brick vaults were used by the end of the 8th century BC. The Pharaoh Ramesses II used barrel vaults for granaries during the 19th dynasty.

The Romans significantly advanced the science of vaulting. They developed barrel, cross, and dome vaults. They used a special volcanic deposit called pozzolana in their mortar. This ingredient made their concrete as solid as rock.

This strength helped neutralize the outward thrust of the vaults. The Romans built massive structures like the Pantheon. They also constructed the Baths of Caracalla. The tepidarium in those baths had a span of 35 meters. This span was more than twice the size of an English cathedral.

Understanding the difference between a vault and a dome is important. A vault is essentially an arch that is extruded into the third dimension. A dome is an arch that has been revolved around its vertical axis.

While they look similar, their geometric origins are different. Both shapes serve to create large, open interior spaces. They allow for grand halls without the need for many internal supports. This ability to span large distances changed how humans designed public buildings.

Vaulting connects the fields of mathematics, physics, and art. Builders must calculate how weight and thrust move through the structure. For example, in a groin vault, the thrust is carried to the cross walls or piers. If the vaults are not the same size, the groins can become twisted and difficult to build. This requires careful decoration with stucco to mask the complexity. From the small mud-brick homes of Cyprus to the massive stone cathedrals of Europe, vaults demonstrate human ingenuity. They show how we use geometry to master the physical world.