Roofing in Yemen

Yemen's tower houses are among the tallest earth buildings in the world. In the Old City of Sana'a, more than 6,000 houses rise several storeys on stone ground floors, built of rammed earth and fired brick with flat roofs; in Shibam, in the Hadhramaut, about 500 mud-brick towers reach up to eleven storeys. Their roofs and wall heads survive only through constant maintenance.

Climate and hazards

Sana'a sits in the highlands, while Shibam lies in the hot, dry Hadhramaut valley. Rain is infrequent but damaging: wind, rain and heat erode mud brick, and flooding is the most serious threat to Shibam. A tropical storm in October 2008 flooded Shibam and weakened building foundations, and some buildings later collapsed. Armed conflict has also damaged both cities.

Roofing history

Ancient Sana'a. Sana'a has been inhabited for more than 2,500 years, became a trade-route centre by the 1st century AD and a major centre of Islam in the 7th and 8th centuries. Its ancient clay city walls stand 9-14 m (30-46 ft) high.

Shibam. The walled city dates from the 16th century, after a flood in 1532-33 destroyed an earlier settlement; Shibam had become the Hadhramaut capital after about AD 300. Many houses have been rebuilt several times.

Late 19th century. Traders returning from Asia revitalised Shibam.

Modern. Concrete has been replacing traditional materials, which UNESCO identifies as a threat to both cities' authenticity.

Traditional and vernacular roofs

• Sana'a tower houses: five to eight storeys (UNESCO's figures vary by language), with stone ground floors and upper floors of rammed earth (pisé) and burnt brick, decorated with fired-brick patterns and white gypsum; topped with flat roofs. In the Jewish Quarter, houses were lower and the main social room was on the top floor.
• Shibam mud-brick towers: 5-11 storeys, some over 30 m (98 ft), one or two rooms per floor; walls must be regularly renewed with fresh mud. See shibam-tower-houses.

Roofing today

Concrete construction has spread in and around historic cities.

Codes, standards and regulation

The General Organization for the Preservation of Historic Cities in Yemen (GOPHCY) was established in 1990. Historic cities are protected under the Antiquities Law of 1997 and the Building Law of 2002. In Shibam, GOPHCY's rehabilitation programme, supported by GIZ since 2000, has documented 98% of traditional houses and rehabilitated more than 60% of private houses.

Notable roofs

• Old City of Sana'a (UNESCO): over 6,000 tower houses.
• Old Walled City of Shibam (UNESCO): about 500 mud-brick towers; on the List of World Heritage in Danger since 2015.

Sources and gaps

National data on roofing materials, roof-specific local terms, details of traditional roof build-ups (timber, earth and lime layers) on Yemeni towers, and information on modern materials, codes beyond heritage law and industry were not found in published sources.