The age of this proven earthbuilding technique isn’t exactly known. Pliny’s report about Hannibal’s rammed earth watch towers shows it in evidence a couple of hundred years before Christ. The idea of stuffing or tamping mud into a form had to have occurred long before that, as adobe making began thousands of years B.C. and certainly the two methods suggest each other.
And just where rammed soils began in another mystery- for it is found almost everywhere, in all the old cultures- from African cities to the Great Wall of China. Most likely it had multiple origins, born out of many builders’ desires to find an easier way. For that is the great advantage of rammed earth – the soil is moved only a few times, compared to adobes’ many. Add to that the fact that the curing takes place in situ – in the wall itself, and you have eliminated the need for a dry season. In any case, the Romans used the technique as they moved through Europe. The cultures already in place had earthbuilding traditions also- such as the French-Celtic people, who since the beginning of the Iron Age (750 B.C.) had been building out of wood and mud. This was the old balco, a clay and straw mix, built on stone foundations.
No doubt alterations took place as methods were traded, but rammed earth was pushed as far as England, and today, almost every European country has a history of rammed earth construction. One may drive through the Phone Valley of France and on into Northern Italy and see hundreds of farmsteads and walls of rammed earth or pise de terre, as the French call it. Germany had documented the craft with typical efficiency and today, there are lots of examples of rammed earth homes and buildings, some five or six stories high. Indeed, the French and Germans were the main exporters of the technique to the American colonies.
By the late 1700’s and early 1800’s German immigrants had established rammed earth in New York and Pennsylvania. Some of these old homes are still in use, although it is difficult to document them because the dwellers themselves have no idea of wall constructions. It is hard to say who the enthusiasts were along the mid-eastern seaboard, but a least one was Thomas Jefferson. The essence of “owner-coordinator”, Jefferson built his home, Monticello, of rammed earth and he was vociferous about urging other colonists to do likewise. In the same area, another documented structure, the “Hilltop House”, was built in 1773.
Today we find it at 100 Rhode Island Ave., in Washington, D.C. The story is that after WWI, an attempt was made to raze it, but the wrecking contractor gave up after his demolition ball had little effect on the 27″ thick walls. The building was renovated and served as an embassy for a time. Perhaps a reader will drive by the address and write us about its current use.
In New Jersey, an owner-builder by the name of S.W. Johnson raised a rammed earth home in 1806. The site was in New Brunswick and Johnson wrote about the experience in his book, titled Rural Economy.
In the South, the French are thought to have been the main influence for rammed earth, but English planters also used the method. It is believed that a number of the antebellum southern mansions are of rammed earth, but one has done a case by case study to determine this. Between 1820 and 1852, a number of rammed earth homes were built in South Carolina. Most of them, along with a good sized church, are still in use. The only example of a really old rammed earth structure by the Spanish in what is now the U.S., is a house at Saint Augustine, Florida. Built in 1556, the construction may actually be coquina, a sort of ground seashell mortar. The Saint Augustine house is still in use.
Documentation of early rammed earth structures in the United States would no doubt show that they were all built in climates we ordinarily do not associate with earth construction, and yet the proof is there – as it is in Europe, that rammed earth is suitable for both wet and dry climates.
In the 1920’s the U.S. Government and a number of State supported colleges/universities became interested in rammed earth. Research and project commenced at the Agricultural Experiment Station, University of California, Davis, in 1926. That same year, Architect M.C. Betts and Engineer T.A.H. Miller published Rammed Earth Walls for Buildings for the U.S.D.A., also known as Farmers Bulletin No. 1500. By the 30’s, a number of other schools were involved, perhaps the foremost being the South Dakota Agricultural & Mechanical College (now called South Dakota State). There, a number of treatises were published by Ralph Patty and associate L.W. Minium, as a result of field constructions.
This is by no means a complete list, but the point is that during this period, a great deal of research about the nature of rammed earth soils and strengths was carried out, and the results for the most part, are viable today. This research intensified into the early days of WWII. Much of it was a result of the federal government’s interest in building projects for the CCC and WPA. Most of these reports and treatises are long out of print, but can be obtained through Southwest Solaradobe School, certain specialty bookstores, and government reprint services.
By the mid-30’s, the Farm Security Administration hired an engineer by the name of Thomas Hibben to study and design rammed earth residences for rural use. The result was a number of attractive residences built in a 936 at Mt. Olivet, near Gardendale, Alabama. These homes were visited by the Millers in 1976 and by historic preservationist Michael Moquin in 1987. There are occupied and in excellent condition. As the Millers point out, the U.S. government has failed to recognize the truths of its own research, and has done little to promote earthen construction since pre WWII days. Some of this may have to do with lobby pressure by the Lumbermens’ Association, but most of the situation is due to ignorance on the part of bureaucrats who have little interest in digging back to find out what their own government documented in earlier generations.
As the Millers, again, point out, the U.S. Agency for International Development has successfully built rammed earth houses in many parts of the world, but its parent agency, Housing and Urban Development (HUD) has a record of anti-earth construction sentiments within the U.S. This record of anti-earthbuilding attitudes is a 180 degree change over the pre-WWII attitude of our federal officials. Perhaps as we continue to cut timer at the current rate of four times faster than we are growing it, and the process of desertification continues, we will see a change in federal attitudes.
Taken From The Earthbuilders’ Encyclopedia by Joseph M. Tibbets 1989. Now available on CD from www.earthbuilder.com