Nubian Vault

The Nubian vault is a method of roofing a room with a barrel vault of sun-dried earth bricks, built without any centring or formwork. The technique originated in Nubia, along the Nile in southern Egypt and northern Sudan, and is now used in the Sahel as an alternative to roofs that depend on imported sheet metal or scarce timber.

How it is built

The mason first builds the end (gable) walls. Bricks are then laid in inclined courses leaning against a gable wall, so each new course sticks to the one behind it while the mortar sets. Because the courses are tilted rather than vertical, no temporary support is needed. The curve of the vault follows the shape of a hanging chain, which keeps the structure in compression. The same principle can be used to build domes.

The whole roof is earth: walls, vault and finishing layers. Waterproofing is provided by a thick earth render on top, which needs maintenance after the rainy season.

Revival

The Egyptian architect Hassan Fathy saw the technique in the Nubian village of Abu al-Riche and revived it in the 1940s. He used it at New Gourna near Luxor, a planned village that was influential architecturally even though many intended residents did not settle there.

Sahel programme

Since 2000 the association La Voûte Nubienne (AVN) has simplified and codified the method and trained local masons. Early work focused on Burkina Faso, Mali and Senegal. The association reports more than 8,500 buildings completed, including homes, schools and health centres, more than 4,900 masons trained and certified, and activity in seven countries.

Why it is used

• No timber. Wood for roof beams is increasingly scarce and costly in the Sahel.
• No imported metal. Corrugated iron roofs are expensive and become very hot.
• Thermal comfort. Thick earth roofs and walls buffer daytime heat.
• Local skills. The technique creates employment for trained masons.

Limitations

Earth vaults are heavy, require skilled bricklaying and need a good protective render; standing water or poor drainage can damage them. Spans are modest, typically single rooms.