LIVING IN THE EARTH

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David and Lydia Miller have built five rammed earth homes since 1945, and they plan to spend the rest of their lives...

by David and Lydia Miller

In an era which tends to celebrate the new and shun the old, rammed earth construction stands out as a paradox: After all, the millennium—sold building method may well also be the technology of the future ... which we are just now returning to.

No one knows exactly when the first rammed earth edifice was built, though historians agree that the process was employed by the Romans—during the heyday of that nation's empire—to build structures in conquered lands. In fact, the Romans spread the use of earth construction throughout Europe ... and today, in France (where rammed earth is known as pise de terre), numerous 400-year-old rammed wall homes still shelter their occupants with a measure of comfort and security which no "modern" frame edifice can offer.

You see, because rammed earth has such a low rate of thermal conductivity (it's actually near zero), warmth takes almost 12 hours to work its way through a 14"-thick wall. The half-day rate of heat transfer makes the material a perfect substance for providing thermal mass in passive solar construction ... since the sun's warmth will actually be reaching the interior of the house during the cold hours of the night.

In addition, the compressional strength of rammed earth can be as high as 625 PSI, which—though it's only two-thirds the value of a similar thickness of concrete—still makes a rammed earth building nearly as durable as a bomb shelter.

Why then—if rammed earth construction is so strong and so time—honored hasn't this building method caught on in the United States? Well, the fact is that it did ... once, Ralph Paddy (of South Dakota State College) conducted extensive research into earth mixtures and building forms back in the thirties.

Then— in 1938— the U.S. Department of Agriculture actually erected an experimental community of rammed earth buildings. The results of that test were quite positive: The USDA's final report noted that rammed earth structures—which would last indefinitely— could be built for as little as two-thirds the cost of standard frame houses. The earthen abodes were also shown to be considerably less expensive to heat and cool, and—because the homes were labor (as opposed to material) intensive—it was clear that they would allow do-it-yourselfers plenty of opportunity to save money.

We can only speculate as to why postwar America snubbed the rammed earth concept: Perhaps the modest pise technique seemed too basic in the face of our newly formed technocracy. Or it may have been the construction industry—which depends so heavily on material intensive methods for its livelihood—that helped deprive rammed earth of its rightful position in building. Furthermore, the public's then increasing yen for miracle synthetics certainly had something to do with the lack of acceptance for so "earthy" a technique.