Earthwall Backgrounder

Down to Earth:

The ancient rammed earth construction method has been reinvigorated by today’s green lifestyles.

Raw earth as a building material is as common as, well, dirt. Archeological evidence dates entire cities constructed of earth back over 10,000 years. All the great civilizations in the Middle East were constructed with mud brick and rammed earth. Walls built of raw earth continue to stand in China, Africa, and even the cold wet climates of Northern Europe.

earthwall-diagram

Post Tensioned Rammed Earth Cut-Away Diagram

The technique of compressing or tamping earth into forms to create structure was first used in arid climates with little wood or other resources. In the third century BC when Hannibal crossed the Alps with his army and elephants to wage war on Rome, he used rammed earth construction for watchtowers. The Romans, in turn, spread the technique in Europe around the first century AD. As a paean to its longevity, some very old structures including portions of the Great Wall of China, several buildings in France, Germany, and England from the 1500s, and an assortment of U.S. homes built in the 1930s are still in use.

The basics of rammed earth construction remained essentially unchanged until the 18th century, when a French builder, Francois Cointeraux, discovered what was called Pisé construction around Lyon. Drawn to its simplicity and uniqueness, he began a series of experiments and documented the basic construction methods. He saw rammed earth as a means by which the common man could vastly improve the quality of his life. The ideals of free earth and honorable labor neatly fit those of the French revolution. Cointeraux went on to found a Parisian Construction school in 1788, and to write four textbooks that became the accepted resource over the next century.

Even though Cointeraux’s work began to gain wide acceptance, the development of more efficient timber construction techniques and the creation of cheaper, more quickly assembled mass-produced materials in the wake of the industrial revolution drastically reduced interest in rammed earth building. In truth, the civilized world viewed earth housing as only for the poor.

Rammed earth saw a brief resurgence of interest in the 1920s, when the U.S. Department of Agriculture studied rammed earth structures built more than 70 years earlier. Surprised by its strength and longevity—and spurred by the Depression’s shortage of building materials and availability of cheap labor—the department published complete technical papers detailing rammed earth construction techniques, which allowed novice homeowners to construct their own houses affordably. But with World War II, and a construction industry moving toward more manufactured component-based building, earth building, now denigrated as old fashioned, again fell out of favor.

The ancient technique began another revival in the 1960s with the back-to-the-earth movement. Interest was further spurred by the late 1970s oil crisis because of earthen housing’s thermal efficiency. In the recent past, rammed earth has gained increasing popularity as a growing group of consumers desiring more environmentally sensitive lifestyles have made being green mainstream, inspiring more architects and builders to use and improve on age-old methods.