Ancient technique solves a modern housing economics problem

In sub-Saharan Africa, traditional building techniques are no longer feasible due to increased deforestation; adapting an ancient architectural technique used in Sudan and Asia to West Africa provides an affordable alternative. The Voute Nubienne (VN) or Nubian Vault technique uses local materials (mud bricks dried in the sun) and local labor to construct low cost vaulted roofs. Earth roofs in the Sahel, a program of the Association La Voûte Nubienne, has been providing communities with a practical option to building with imported metal sheet roofing materials and expensive timber since 2000. 

In sub-Saharan Africa, timber was used traditionally for roofing. Flat beams and rafters were made from rough timber and branches, supporting laths covered in earth; such roofs are supported by adobe/mud walls, incorporating load-bearing timber posts. But population growth, along with increasing desertification, means such traditional building techniques are no longer feasible.

People in rural areas now have to resort to buying sheet metal (corrugated iron) and sawn timber beams and rafters for roof-building, but finding the cash to pay for such imported building materials is often a problem for families living outside any formal economic system.

The ancient architectural technique,  “la Voute Nubienne” or VN,  makes it possible to build houses with vaulted roofs (on top of which a traditional flat roof terrace can be constructed) using basic, readily available local materials and simple, easily learnt, procedures. The only raw material used is earth, both for making mortar and for mud bricks dried in the sun. Timber shuttering is not needed to support the vault during construction. The traditional methods have been simplified, and adapted, to provide protection during the short but heavy rainy seasons in sub-Saharan Africa.

The major cost element in using the VN method is labour, thus keeping cash in the local economy; the raw materials are locally available and ecologically sound. The VN technique has been adapted to match the prevalent customs and traditional ways of imparting skills, especially in rural communities. The result is a streamlined technique, easy both to put into practice and to teach by example.

Since the first VN building was built in Burkina Faso 10 years ago, more than 340 vaults have been built, 60 VN builders have been trained and are setting themselves up as local entrepreneurs, and 100 apprentices are undergoing training on VN building sites. The method has spread from Burkina Faso to Mali, Senegal, Togo and Ivory Coast.

Buildings include a mosque and a Catholic church as well as village homes. Most VN buildings to date are in rural areas, but the VN technique can be used in denser urban and peri-urban zones. The additional expense of transport of bricks and water to urban sites, and higher labour costs, may be counter-balanced by lower material costs, especially for two-storey buildings, when a VN vault can replace a costly reinforced concrete structure. Three case studies are available on the project website.

The AVN hopes that by 2030, 80,000 builders will have been trained in the technique, that 2 million VN buildings will exist in sub-Saharan Africa, and that 12 million people will benefit from their construction.

This story was compiled from information on the Cooper-Hewitt Museum blog, an article in Wikipedia, and the AVN website. You can see a video of the technique being used here. Contact: Association « la voute nubienne », 9 rue des Arts, 34190 Ganges, France. Email. All 3 pictures come from the Voute nubienne website.

UPDATE:  AVN's Burkina Faso project a winner in 2009 global competition

The AVN is one of 26 winners of the 2009 Global Competition of the Development Marketplace, on the theme of Climate Adaptation. The Development Marketplace grant will allow the AVN and La Voute Nubinne to undertake a pilot project to train farmers in Boroma district, Burkina Faso, in how to build houses with vaulted roofs of earth bricks.

The Development Marketplace is a competitive grant program administered by the World Bank. The 2009 global competition, funded by the Global Environment Facility (GEF) and additional DM partners, aimed to identify 20 to 25 innovative, early-stage projects addressing climate adaptation. The 2009 competition was held Nov. 10-13, 2009.

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