A barrel vault, also known as a tunnel vault or a wagon vault, is an architectural element formed by the extrusion of a single curve (or pair of curves, in the case of a pointed barrel vault) along a given distance. The curves are typically circular in shape, lending a semi-cylindrical appearance to the total design. The barrel vault is the simplest form of a vault: effectively a series of arches placed side by side, i.e., one after another. See Wikipedia
The construction of barrel vaults is common in the vernacular architecture of the pioneer colonists of South Africa, particularly for the construction of Powder Houses, Bread Baking Ovens and Whip Haft Kilns.
The construction technique was again popularised by the MOMA exhibition and publication ‘Architecture without architects’ (19??) following the example of the Egyptian architect, Hassan Fathy (especially in his publication, ‘Housing for the poor’, 19??), especially as used for brick vaulting in experimental housing by Dave [?] Birrer in Cullinan, and Keith MURRAY’s own house in Zimbabwe and the domestic works of the time of Frederik [Freddie] SNYMAN in Pretoria.