Rebuilding Yemen’s Mudbrick Treasures

This article is from Yemen Today Magazine, written by Will Raynolds.

From the ancient dam at Marib to the highland fortifications of stone hewn by Himyarite hands, Yemen has a rich tradition of ambitious construction. More recently, Yemeni architecture has received considerable recognition on the global stage, with three cities listed by UNESCO as World Heritage Sites: the mud brick city of Shibam, the Old City of Sana’a, and the historic town of Zabid. Additionally, restoration projects in Shibam, Anaf and Radah have received the prestigious Aga Khan Award for Architecture.

Now, one of Yemen’s most masterful architectural traditions, the earthen architecture of the Hadhramaut Valley, has suffered a tremendous blow. The flooding at the end of October resulted in the tragic loss of over 200 lives and the damage or destruction of over 3,500 homes, almost all of them made of mud brick. The Hadhramaut enjoys one of the highest concentrations of earthen architecture anywhere in the Middle East, or indeed the world. Unlike the buildings of the Yemeni highlands which are generally made from stone, the traditional architects, masons, and artisans of the Hadhramaut build out of mud from the earth. Indeed, the Hadhramis have taken the techniques of earthen construction to a new stature, and their mud brick buildings are unparalleled in both their scale (some as high as 9 stories) and decoration (styles ranging from Indian Mughal to Art Deco).

From the steppes of China to the fringe of the Sahel in Mali, people around the world have found that living in earthen buildings is one of the best ways to beat the heat. Such traditional building technology also performs well in the Hadhramaut, where thick mud-brick walls insulate against the daily and seasonal temperature extremes of the arid climate. The mud bricks themselves are made of a combination of clay-rich soil and water The water is added to the soil until it is plastic enough to be shaped into a brick but still dry enough to retain this form on its own.

Brickmakers pack the raw slurry into molds of uniform dimensions, laying rows of unfinished bricks on the ground to dry in the sun. Under optimal drying conditions, the bricks will be dry enough to tilt on their sides after a day, allowing the underside to dry out more thoroughly.

Within a week, the bricks will have cured completely and are ready to be incorporated into a building. Mud brick masons in the Hadhramaut typically build during the winter months, starting with a thick foundation course so that the building will be able to support multiple stories. They complete one story per year, forming the walls with mud-bricks joined with a more clay-rich mortar. After the completion of a story, they leave the roof open, allowing the walls a chance to thoroughly dry. Therefore, before they can start construction on the subsequent story, they must first fashion the roof of the floor below from a lattice of woven reeds and beams made from the termite resistant ‘ilb wood.

Generally, these Hadrami buildings perform exceptionally well, even under the rains of the Indian Ocean Monsoon. Yemeni builders have developed several different lime plaster coating systems, preventing water from infiltrating and compromising the structure of a mud brick building. Local artisans typically classify these lime-plasters according to three broad headings: nurah, neat lime plaster typically used for sealing a building’s exterior; malis, a polished lime plaster often used for floors and wainscoting in a building’s interior; and ramad, a pozzolanic lime plaster that can harden under water.

All of these materials are made from limestone, which is quarried locally from outcrops with the help of explosives. Raw limestone boulders are stacked in a honey-comb pattern inside of a kiln, where they are exposed to the intense heat of a fire fueled by old tires, palm wood, and other flammable materials. After stoking the fire continuously for two days, lime makers will remove the boulders from the kiln. While these rocks physically appear to be the same as they were going into the kiln, the heat has chemically transformed the limestone from calcium carbonate into calcium oxide, or quicklime. Workers bundle the quicklime into rice bags and transport it to a slaking facility, where the boulders are placed into a vat and water is poured over their tops. This step initiates another chemical transformation, turning calcium oxide into calcium hydroxide, or lime putty. Because this reaction is quite vigorous and emits a large amount of heat, this is the most dangerous part of the entire process. When water is first poured on the boulders of quicklime, they literally explode. As the mixing continues, the reaction dies down, but the vapors wafting off the mixing vat remain caustic. Putty-mixers must be cautious because long term exposure can result in lung-damage and blindness. However, putty-makers often stand over the lime all day, beating the product by hand with long wooden clubs to break up unreacted lumps and attain the right consistency.

After achieving an even mix, this lime putty is ready to be applied to a building in the form of nurah, malis, or ramad. Once it is applied to the surface of the mud bricks, the putty hardens as it is exposed to carbon dioxide in the atmosphere. Calcium hydroxide becomes calcium carbonate, which is another name for limestone. In this way, the artisans of the Hadhramaut are not just applying beautiful decoration to their buildings, they are literally protecting them with layers of stone. However, the unprecedented severity of the storm in October overwhelmed these defenses. Many buildings were only partially coated with lime plaster, allowing the strong and continuous rain to penetrate and undermine the foundations of buildings in places where the mud brick was still exposed.

Following the flood, Yemen has been fortunate to receive relief funding from its neighbors and other foreign governments, most notably Saudi Arabia, which has donated $100 million. Certainly, much of this money must be dedicated to providing food, medicine and temporary housing to the flood victims. However, Yemen must also allocate funding and strive to repair and rebuild the buildings damaged by the disaster. The elaborate construction process outlined above involves multiple industries, employing thousands of people throughout the Hadhramaut, all beneficiaries of efforts to rebuild the many buildings which have been lost. The knowledge and art required to accomplish such an ambitious project are very much alive and well, and remain among Yemen’s greatest archaeological assets. In past years, international organizations such as the Deutch Gesellschaft für Technische Zusammenarbeit (GTZ) have played a commendable role in incorporating the building arts into their broader scheme for sustainable development. Now Yemen must decide what role the traditional builders will play in the reconstruction following the flood. Let us hope that the brightest day of Hadhrami earthen architecture has yet to come; that the greatest mud-brick buildings in the Hadhramaut have yet to be built.