JULY 2006 »  book review

Breaking Old Ground

Building with Cob: A step-by-step guide
by Adam Weisman and Katy Bryce
Green Books Ltd., Devon, U.K.; 2006
256pp.; softcover; 360 color photographs; 65 diagrams; $45
ISBN 1-903-99872-7

Reviewed by Lynne Lavelle

Though resource depletion and climate change grab the headlines, the physical and emotional separation of man from the land is the Industrial Revolution’s most keenly felt legacy. Vernacular house building has all but disappeared in many areas; it’s a forgotten skill lost to mass-production, with devastating consequences for the environment. More than 100 years on, the housing industry contributes to more than 50 percent of all the pollution in the world. Cement processing alone is responsible for 8 percent of total greenhouse emissions.

Architects, builders and consumers are at a crossroads and, according to Building with Cob: A step-by-step guide, blind faith in an unsustainable future is not an option. Rather, the answer lies in a combination of clay, sand and straw known as "cob," and getting our hands dirty again. It is a reminder that "traditional" is more than just style or aesthetic imitation, it also pertains to techniques and materials used. In this sense, there can be none more deserving of the term than earth.

This step-by-step guide to one of the world’s oldest building materials takes the prospective builder from the site and design of his or her cob home, oven or fireplace, through the building process and restoration. Authors Adam Weissman and Katy Bryce specialize in cob building throughout the southeast of England, and formed their company, Cob in Cornwall, following apprenticeships with the Cob Cottage Company in Cottage Grove, OR. Theirs is a philosophical approach – earth building as a utopian lifestyle choice and a rejection of the concrete "graves" of mass-produced housing.

Unbaked earth remains the predominant building material in South and Central America, China and Africa, which account for a third of the world’s population. And in the U.S., straw bale and adobe building have become almost mainstream, particularly in the Southwest and California, where the thermal-mass properties of these buildings ideally moderate the temperature. Yet cob is considered a forgotten, or worse, "hippie" technique throughout much of the U.S. and Europe. Building with Cob does not fully explain why – that would be a very different book – but assesses the impact of this decline, citing community cohesion and an appreciation of nature’s limitations as its major casualties. A desire for "style and fashion over pragmatism and appearance over practicality" sums up the harsh indictment of mass-produced housing throughout.

Building with Cob promotes natural building as a cathartic alternative; a community experience in which grandmothers, children and "stressed-out executives" alike can participate. It is a highly labor-intensive process however, and only the most ambitious first-timers are likely to go it alone. The authors write from the perspective of self-builders, but hiring environmentally responsible builders and architects is the most common route, aided by the relatively low cost of materials. These can be almost free if sourced on-site, and the ease with which this can be done is a good indicator of the suitability of the land for cob building.

The authors are confident that even urbanites can determine good subsurface geology from bad, offering brief pointers on drainage, orientation and "discovering where you are intuitively drawn." Outside of Cornwall, this advice is most pertinent. The highest concentration of cob homes in the U.S. is found on the southern West Coast, with good reason. The authors could have ruled out tracts of the U.S. and Europe for cob-building on the grounds that their cold climates dramatically lower the chances of achieving stable builds. But the authors are not just craftspeople, they are fans, and even the most trying aspects of working with cob are given a positive spin, usually as an opportunity to bond with nature. The process itself is given nobility, and the text is interspersed with quotes and extracts about the health, happiness and balance that earth structures promote, plus asides about their "sensuous curves."

Happy people forming cob structures in limitless shapes, forms and hues will inspire even the most ardent indoor-types to reconsider the stuff beneath their feet. Cob is composed of 15-25 percent clay, mixed with 75-85 percent aggregate and straw, the most plentiful materials in the world. In determining the best combination, builders are encouraged to become very familiar with their cob. Touching, smelling and even tasting the earth are legitimate tests for texture. Since the rural farmers who first built with cob didn’t write down their methods, cob building has remained fluid, with few rigid ideas about correct or incorrect practice. Building with Cob offers instructions with no greater authority than "what works for us," and often gives alternatives learned from friends and other cob companies.

Ideally, cob building begins in the spring and is completed in the fall to afford adequate drying time between each application of cob, or "lift." A finished structure can take up to a year to dry completely, and technical skill is no substitute for patience or an ideal climate – moist but dry, warm but not hot. Natural, breathable paints and lime washes are recommended for the finishes, and many structural problems are attributed to the use of nonporous materials, such as cement, which are incompatible with earth and "suffocate" the wall.

Much of Building with Cob is devoted to insulation and passive solar- heating principles, which minimize dependence on fossil fuels and maximize cob’s excellent thermal-mass properties. Passive solar design, not to be confused with solar power, is a millennia-old principle that utilizes the position of the sun to store heat within the walls, for release when the temperature drops at night. Every aspect of the building, from its shape to the position of the north wall, is designed around this principle, which masks cob’s poor insulation properties and supports self-containment and sustainability.

Building with Cob links the renewed interest in natural building to the resurgence of local dialects, indigenous music and organic food. In short, it stresses greater awareness of what exists around us and how it can be harnessed, rather than destroyed. It asks that we consider cob building as more than a means to an end, but as the healing of a broken bond – or a great excuse to get muddy.  

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