Mirror vault

A mirror vault, aynalı tonoz in Turkish, covers a square or rectangular room with curved surfaces rising inward from all four walls, closed at the top by a flat horizontal panel. That flat centre is called the mirror, and the vault takes its name from it. In section you see a quarter-vault at each side and a level plane in the middle.

Role in the building

A mirror vault covers a room and ties into all four walls without adding much height. The curved sides spread the load onto every wall, so the thrust is not concentrated on two walls as in a barrel vault. The flat mirror, though, needs careful bonding or intermediate ties in masonry, because a horizontal masonry surface cannot work as an arch. For that reason the mirror is usually kept small or built in lighter material.

• Side surfaces: curved sections rising from the four walls
• Corner junctions: edges where two side surfaces meet
• Mirror: the flat, horizontal panel at the top

Mirror vault and ceiling medallion

A similar form appears in timber ceilings of traditional houses: a curved or chamfered cove at the edges, a flat ceiling in the middle and often a carved central medallion. It recalls a mirror vault in shape, but it is usually a lining rather than a structure, and a survey must make that distinction.

Survey and 3D modeling

Record the height of the mirror, the profile of the curved sides and the corner edges. In 3D the sides can be built by sweeping a profile along the four walls; check the resulting corner intersections against the measured edges.