 |
 |
||
Cheap, Sustainable Building Materials? You’re Standing On It!by
|
 |
 |
A housing crisis exists. As the population continues to grow exponentially, housing will become an even greater issue than it is already. Where will all the people live? Or more appropriately, in what will they live? How can we house people in structures that are safe, long lasting, and beautiful? The answer is right under your feet: earth. The durability, availability, and possibilities of earth make it the materials choice for long-term housing solutions.
It is quite humorous when someone refers to earth architecture as “alternative.” Historically speaking, stick frame housing is definitely the “alternative.” Archaeology provides us with countless structures exemplifying the qualities of earth that make it desirable to build with. The old walls and palaces of the Middle East, the mosques and homes of Western Africa, and the kivas and dwellings of the Native Americans all illustrate the importance earth has played in housing humanity throughout history. Even Europeans, ancestors to American stick-framers, used mud for construction. England, France, and Germany all have thousands of earthen buildings. Between the end of World War II and 1970, it is estimated that 40,000 German homes were built of earth. The Missions of California and homes of the Spanish colonial period are a testament to our own golden California soil. How many years, how many disasters, and how much change have these buildings endured, right here in our own backyard? Earth is fireproof, infestation proof, and performs better thermally than conventional buildings. Obviously, earth works and works well. And, as the price of lumber increases and the quality decreases, and the true environmental impact of deforestation is painfully realized, earth will be the outstanding choice to build our homes and communities.
Another goal of sustainable housing is to use resources locally available. What is more ever-present than our beloved earth? To take it even one step further, what is most available on any planet other than native soil? In 1984, renowned architect, Nader Khalili, presented a technical paper to NASA offering his solutions for shelter on the Moon and Mars. He proposed generating double-curvature shell structures fired in situ. Huh? For the non-rocket scientist, he proposed building domes out of lunar or martian soil. Not only does building with earth satisfy bioregionality, it connects us to universality. Back here on the planet earth, local soils, suitable for building with, are readily available. Quality building materials are being excavated and dumped by quarries, commercial and industrial building sites, and infrastructure improvements. Maybe the “dirt” in your backyard is suitable to build with. These materials are cheaper, longer lasting , less toxic, and contain less embodied energy than just about any commercially available building product. True, some processed products are required by building codes for soil stabilization, but these account for 10-15% of the final soil mixture used in construction. The knowledge and testing needed to satisfy the building department’s standards for earth as a building material are not beyond the scope of any dedicated architect, engineer, or owner-builder.
Earth is a material that craves human input, an element desperately missing from conventional building. It is plastic, moldable, and sculptable. Therefore, a variety of building applications exist. Some of these techniques include adobe, cob, and sandbag, or Superadobe.
Adobe is perhaps the most familiar. It is a word that clearly conjures up images of pueblos, missions, and southwest architecture. Adobe is our earth-building heritage here in California. Technologically, it is basic. Wet mud is poured into rectilinear forms, allowed to dry to firmness, and stacked together for a longer curing period. Traditionally, straw has been added to adobes as complementary tensile members, to reduce the block’s weight, and when soaked with the mud prior to forming, a natural waterproofing. Presently, adobes are stabilized either with pozzolanic materials (cement, lime, etc.) or, more commonly, asphalt emulsion. New Mexico and other southwestern states have an ongoing tradition of adobe building which supplies us with vast amounts of technical data and construction procedures. Good sources of information include books by Paul Graham McHenry, journals published by the Southwest Solar Adobe School in Bosque, NM, and the many, many historical examples of adobe located right here in California. Santa Barbara, San Luis Obispo, and Ventura counties all have fantastic adobes.
Presently, adobe building in this area continues. Event hough we are located in the highest recognized seismic zone, engineers have developed reinforcing strategies unique to adobe. Currently, adobe is being widely used at the eighty-thousand-square-foot Sanford Winery construction site located west of Buelton. Also, permitted adobe structures are being built by historical and earthen enthusiasts. The Ojai Foundation has constructed two small multi-purpose buildings using pressed adobe, a high-tech, mechanized production process.
Cob, or coursed adobe, is an even simpler process. Mud and straw are mixed together, commonly by foot. Wet gobs of material are placed on the walls and built up course by course, “cobbing” the newer layer to the preceding. The wet-on-wet additive construction makes cob walls monolithic and stronger than adobe block walls. No formwork is used and the result is a truly handmade house. The leading source for information about cob is the Cob Cottage Company out of Cottage Grove, Oregon. Michael G. Smith, a co-founder of the Cob Cottage Co., is also the author of The Cobber’s Companion: How to Build Your Own Earthen Home. Anyone who is interested in cob will find it an excellent resource.
Cob is not as acceptable to building officials as other more formalized techniques. Its low-tech, low-cost approach lends itself to the do-it-yourselfer. However, there is a contingency out there working towards obtaining permits for cob structures. A beautiful cob building was built last year at the Ojai Foundation (see photo on p.50).
The California Institute of Earth Art and Architecture, Cal-Earth for short, is building with earth, using cutting-edge technology and timeless principles. Nader Khalili’s designs are putting the arch back in architecture. Along with other dedicated individuals, Khalili has developed a technique coined “Superadobe.” Continuous sandbags are filled with stabilized soil, rammed in place, and coursed together to form arches, domes, and vaults. Using arches, domes, and vaults greatly diminishes the need to use wood, especially for roofing. And the strength of Cal-Earth’s arched structures is impressive. In the September/October 1998 issue of the ICBO’s “Building Standards” magazine, City of Hesperia Planning Director Tom Harp recalls, “Testing (of the earthen structures) continued beyond agreed limits until testing apparatus began to fail. No deflection or failure was noted, however, on any of the tested buildings.”
Projects at Cal-Earth include a 2,000-square foot permitted sandbag home, a 5,000-square-foot permitted Natural History Museum for the city of Hesperia, and numerous other experimental structures. The Hesperia City Council recently approved the resolution to build a Lunar/Planetary Colony Prototype at Cal-Earth Institute. Locally, the Ojai foundation has used Superadobe in structures and for a plaza with benches and a fountain. Local or on-site soils were used in all these projects.
Martin Hartmann