It’s a blistering 90-degree day in the arid valley north of San Francisco, so entering Suzanne Brangham’s lavish hillside home is welcome relief. It is cool in the living room under the 19-foot Douglas-fir beamed ceiling, cool in the kitchen beside the antique pine wine cask from England, cool in the main bathroom behind the 100-year-old mesquite doors from Mexico.
Good air conditioning? No, good dirt: The walls of her $1 million-plus home are made not of plaster but of tightly-packed soil, 18 inches thick, that holds heat during the day and releases it in the cool of the night. The overall sensation is somewhat akin to being in a well-lit — and ever so tastefully decorated — cavern. “There is a peacefulness, an aura about these thick walls,” Brangham says. “I feel like I’m surrounded by earth.”
The peach-colored walls in the 4,200-square-foot home were made in a process known somewhat indelicately as “rammed earth” that is gaining a small but devoted following among high-end and environmentally conscious builders, architects and homeowners in the Southwest and West. Drawn to the solid feeling, energy-saving properties and distinctive look, buyers are willing to spend as much as 50 percent more than they would for conventional wood-frame walls.
“Ten years ago, people said it was off the wall — here’s another geodesic dome,” says Tom Wuelpern of Rammed Earth Development in Tucson, one of about 20 rammed-earth builders around the country. Now, he says, “the higher-dollar community . . . considers it a legitimate building material.” Adds Quentin Branch of Rammed Earth Solar Homes in Tucson, a veteran builder: “Each year I build progressively larger and more expensive homes.”
Rammed earth isn’t exactly new — or high technology. There is archeological evidence of rammed-earth construction 10,000 years ago in the Middle East. Sections of the Great Wall of China were built of rammed earth. The Roman historian Pliny the Elder wrote in the first century of houses in Spain and Africa made of earth stuffed and packed between two boards that “last for ages, undamaged by rain, wind and fire, and stronger than any quarry stone.”
Interest in rammed earth in the U.S. surfaced in the middle of the last century; farmers were common earthbuilders. The government published a how-to manual in the 1930s, and hundreds of rammed-earth homes were built during the Depression. But the flush post-World War II economy and improved building techniques made wood-frame homes easy and quick to build, and rammed earth faded away. It wasn’t until the 1970s that a handful of Western architects and builders, influenced by the nascent environmental movement, began building with rammed earth.
After two decades of slow but steady business, several top rammed-earth builders say business has more than doubled in recent years. Seminars on rammed-earth and adobe construction at the Southwest Solaradobe School in Bosque, N.M., attract more than 100 students a year. Environmental groups tout rammed earth as one of a handful of “alternative” building techniques. Lenders are becoming less wary about financing homes made of earth. And glossy design magazines feature rammed-earth homes, attracting ever-wealthier clients.
Just don’t call their showplaces “mud.” Devotees point out that topsoil from your average garden just won’t do; rammed earth walls actually consist of clayey, mineral-laden soils found deeper beneath the surface mixed with 3 percent to 10 percent cement, depending on the location, and water. (The extra cement, along with steel reinforcement inside the walls, provides stability in earthquake regions.)
The earth is then pounded by hand or mechanical tampers into plywood “forms” that are set in the foundation of the structure to define the length, width and height of the walls. Spaces are built into the forms for doors, windows and other flourishes, and striations of different-colored soils and gravels can be added for aesthetic effect.
Properly constructed rammed-earth homes don’t leak or crumble in the rain. But you may not want to try this one in, say, Seattle. Right now, rammed earth is concentrated in the deserts of Arizona and New Mexico, the valleys of Northern California and a few Colorado mountain hamlets. Experts say while rammed earth could work effectively in colder, rainy climates, it requires a lot of additional insulation.
That can raise the cost of what already is a more expensive home-construction method. David Easton of Napa, Calif., who has built more than 100 rammed-earth homes, including the Brangham’s house, says a wall system in a high-end rammed-earth home can cost 30 percent to 50 percent more than in a conventional wood-frame house, raising total construction costs by 5 percent to 15 percent. Much of the added expense results from the labor-intensive process and the extra few weeks required to build a set of rammed-earth walls.
But for high-end buyers, the look and feel make money no object. Easton has been contracted to build a planned $5 million, 12,000-square-foot rammed-earth house in Sonoma. The Fetzer winery is one of several in Northern California that include buildings of rammed earth. Brangham is on her third rammed-earth house, the first of which she sold for $1.3 million. Branch was recently contracted to build a $1.6 million rammed-earth house in Scottsdale, Ariz.
“It’s so unique that if it did cost a little more, it’s worth the investment,” says Roberta Isgreen, who with her husband, William, had Easton build their $1 million rammed-earth house in Glen Ellen, Calif., two years ago. The front walkway features rammed-earth columns covered in trumpet vines, while inside a concrete beam that runs across the top of the walls is given a faux-marble finish.
Other homeowners are taken with rammed earth’s efficiency. Stephen and Vicki Rutter’s new three-bedroom house sits on 68 acres of former ranchland in Patagonia, Ariz. Dr. Rutter, an ear, nose and throat doctor, and his wife, an accountant, installed a radiant floor heating system, which they haven’t turned on yet. As for their central air conditioning, “I think we used it all of about four hours this summer,” Dr. Rutter says.
Rick Heede, a research scholar at the Rocky Mountain Institute in Old Snowmass, Colo., says the annual energy bills for his 4,000-square-foot home with 24-inch-thick rammed-earth walls are about one-eighth of those of other local homeowners. Not that his house is chilly: The extra insulation and solar panels he installed make sure of that. “I’m not a Luddite,” he says.
There are other green aspects to rammed earth. “You’re using indigenous materials, native soil right there,” says Steve Loken, president of the Center for Resourceful Building Technology in Missoula, Mont. “You don’t have any transportation charges or manufacturing energy costs. It doesn’t get any more basic than that.”
But as more builders hear about rammed earth, more seem willing to try it — not always with good results. Branch recently was called to the mountain town of Buena Vista, Colo., to finish three rammed-earth jobs shut down by local building officials. The walls were out of plumb, shrank and developed large cracks. The reason: inaccurate soil mixtures, too much water and inexperienced builders.
Ignorance about so-called sustainable building techniques like rammed earth has hampered growth, builders say. Top builders in New Mexico are working with state officials to develop the first rammed-earth code for the construction industry to specify wall thickness, energy-conservation guidelines, soil mixes and ramming procedures. Environmental groups want revisions to standard building codes to encourage the use of alternative building techniques.
Rammed-earth builders hope to expand the market beyond the wealthy. Easton has cut costs by developing a process in which the soil mixture is shot into place using hoses similar to ones for building swimming pools, which results in a finish that is bumpy like stucco rather than smooth and striated like exposed rammed earth. But as the costs of conventional wood-frame construction rise, the added expense of a rammed-earth home seems less imposing. Anyway, says Heede, the rammed-earth homeowner in Colorado, “I wanted something unusual. Anyone can build a stick-frame house.”
