Throughout Portland, Oregon and the Pacific Northwest, cob (an ancient building technique of mixing clay, sand, and straw) has found new appeal. Associated closely with the Natural Building movement, cob benches, ovens, interiors, studios, sheds, and even entire homes now accent our community. Most recent cob structures carry strong ‘organic’ and capricious’ imagery; evocative of an expressive and whimsical way of building. Though cob has found acceptance among alternative builders and do-it-yourselfers who embrace these features, it remains almost wholly absent from the Architecture community as a whole. Even in one of the most progressive, sustainably minded cities in the country, cob and cob building remain fringe movements.
But as a material, cob need not be defined through a certain appearance. This 'alternative' approach to building embodies many redeeming characteristics that most people would embrace. In residential, commercial, and community work, cob’s potential remains largely untapped. Sculpted cob elements can become creative and functional centerpieces in an entertainment space, provide unique seating in a sunroom, or create the focal wall in a restaurant. If we can move past certain preconceptions of what cob has to be, we will find at its core a material fully compatible with contemporary design. This post aims to challenge those preconceptions, explain what value cob can bring to a space, and offer ways for the design profession to embrace this most elemental of materials.
The approach to unbaked earth most common in this region is known as ‘Oregon Cob’; the latest in a line of adaptations having evolved over centuries to suit a vast range of climates and cultures. In fact, handmade, unfired earthen mixtures comprise one of the oldest, most ubiquitous building materials employed by humans. Its endemic use spans across Northern Europe, the Middle East, sub-Saharan Africa, South and Central America, and throughout Asia as well. Through the 18th century, cob building became commonplace throughout much of England and Wales. With the onset of the Industrial Revolution, this and other forms of vernacular construction tended to give way to the new, prefabricated materials now readily available.
Still, earth building remains in widespread use throughout much the world. And over the last several decades, cob has made a resurgence within England and the United States. Here in the U.S., this revival began off the grid, as an alternative movement lending itself to use in eco-communities and small, unpermitted projects. As interest has grown, so has the push towards bringing cob into the spectrum of ‘accepted’ materials. But even with greater acceptance and understanding, cob’s use within conventional architecture and design remains limited.
Cob is ECOLOGICAL (in the very real sense of the word); composed of unadulterated, and, ideally, locally sourced materials, most cob buildings maintain a low embodied energy which don’t require large-scale mining or other destructive practices to obtain.
Cob is HEALTHY; in both its final and component forms, cob contains no synthetical chemicals, nor poses longterm concerns for indoor air quality due to off-gassing or VOC’s. This remains true throughout its lifecycle.
Cob is SAFE; with only your hands, feet, tarps, buckets, and a few hand tools, most phases of a cob project can be completed without the dangers of power tools or machinery. This means anyone, regardless of age or ability, can learn to safely work with cob - and often they will actually enjoy the process!
Cob is FLEXIBLE; and can be made to take on nearly any shape. Unlike concrete, cob is fashioned from its base up, not poured into formwork. This methodology lends itself to asymmetrical and undulating forms, varying wall thickness, custom built-ins, and creative openings all personalized to the specific contexts of a project.
Cob is SUBSTANTIAL; its mass has implications both in terms of passive solar heating as with the tectonics of building. Load-bearing cob is structured similar to bearing stone; it likes thick walls that taper as they increase in height, and are strongest at their curves. Openings, vaultings, and niches are all constructed with a similar respect to stereotomy.
Cob is FORGIVING; just as with building a sandcastle, until dry, cob can be continually edited and changed as you perfect your work. Even once set, cob does not cure in the way concrete does; there is no chemical alteration to the materials. If allowed to sufficiently soak, cob will turn back into exactly what it was at the time of installation.
Cob is IMPERFECT; as with anything handmade, the print of the maker is always left in the final product. Contrast your favorite hand-thrown coffee mug to a factory-made ceramic one. The imperfections vitalize it with character and feeling. Just as with people, our idiosyncrasies define us, make us unique, and ultimately special. Picture your mug again; now imagine living in it!
Cob is TACTILE; compare the pleasant physical connection of wood to that of steel. That is analogous to the difference between a cob wall and most fashioned from concrete or gypsum board. Formed earth is warm, inviting, and somehow soft even when it is hard.
Cob is INEXPENSIVE; all necessary materials can usually be obtained cheaply. It is however a labor intensive way of building. Under a conventional model, the human hours needed to complete a cob project may outweigh the initial savings. This is one reason many cob projects have been owner built.
Sustainability, safety, personalization, and warmth are all commonly sought characteristics by people wishing to build or renovate their home. So why is cob construction mostly missing from contemporary design? There are perhaps several contributing factors, but two stand out in particular.
The first is that cob has developed to cater towards a certain aesthetic. Since cob lends itself so well towards organic forms and sculpture, many cob buildings end up expressing these qualities. The effect has been to suggest this is the only way for the material to be used. Although not true, this mentality seems nevertheless to have framed cob’s use within a narrow context. Materials don’t necessitate style, and cob can be articulated as ornately or plainly as the maker desires. This can range from the sculpted animals, trees, or patterns presently common, but could also include a more minimal interpretation, one where the use of sleek lines and subtle textures carry their own power.
The second reason comes down to finances and logistics. Although the raw materials are inexpensive, cob itself requires a lot of manual labor. This of course translates into many hours and/or people to produce. As a result, practicing under the conventional building model, a house built from cob could be comparable or even more expensive than a stick-build one. Even someone who desires the intrinsic characteristics that make working with cob advantageous, the added financial burden may still make it difficult justify.
To succumb to these concerns would be to miss what could be the real potential for cob within our modern context. A material so positive at its core should not be neglected by the design profession, but embraced and pushed to into new arenas. Here are two scenarios where the use of cob, under the focused leadership of an experienced designer, may be financially viable.
Where cob is concerned, there is actually a potential group that might be employed to circumvent those high labor costs; ourselves. Here is how this might work. Your community has decided it wants to add a shade and picnic shelter in the local park. Typically, any funds need to be donated, raised or otherwise obtained to cover every stage of the project including the materials and labor. But what if instead a significant portion of those materials were excavated from the site itself, and the vast majority of labor was donated by the very families whom the shelter would later benefit?
Because cob is fun, safe and conducive to large, unskilled groups, the entire building process can become a community event! Families with children, local politicians, students interested in learning, or simply anyone otherwise curious could join in. The experience would be educational, productive, and most importantly social, as it fostered real interactions between people. With direction from an experienced designer/builder, the greatest challenge would become organizational, not financial. After a few weekends, the new shelter would be well on its way, and the beautiful walls, benches, and floors would have been hand-made by the very hands that would continue to use them. The completed structure would add identity and character to the community.
A second set of situations looks at using cob and natural building practices as a supplemental rather than driving force within design. For both new construction and renovations, if cob was viewed primarily as a great material to accentuate those special moments in a home and not necessarily as comprising the main envelope itself, associative costs would become less prohibitive.
Imagine folding the thermal mass of an elegant cob wall around the wood stove in your contemporary cabin. Your study could enjoy the warmth of a cob floor which sweeps up to form a cushioned window bed mimicking a chaise lounge. Maybe you renovate your standard dining room to flaunt chamfered corners and elliptical walls which bulge around a live-edged table. An accent wall with custom niches and openings could display your praised artwork or travel collections. Or perhaps your favorite room to meditate, which appears rectangular from outside, could actually flow and undulate in ways evocative of nature.
The potential here is limitless, restricted only by our creative ability to reflect personality and preference in built form. Accent walls, hearths, window seats, niches, floors, sculpted room transitions, daybeds, deeply set fenestration, room partitions, or even completely reworked larger spaces are all viable targets. So too would outbuildings, additions, or any other number of elements relating to the specifics of a space. Juxtaposing the handmade character of cob with our common repertoire of factory fabricated materials could truly vitalize a space and infuse it with identify. These would, almost by necessity, be truly customized and formed to compliment the lifestyle, habits, characters, and passions of the owner(s). By focusing on elements and not the whole, we could contain their expense without restricting their expressive nature and the aura of authenticity they bring.
The true spirit of cob lies in its flexibility, flexibility of form but also in how those forms are articulated. By using cob in combination with and as part of a greater sustainable whole, we open ourselves to its vast, overlooked potential. The use of earth in building is as ‘modern’ as we make it; and depends entirely on how it is conceived. Through challenging current assumptions of when and where cob is deemed appropriate, these possibilities for handmade community buildings and accent architecture become viable. Both scenarios embrace the nature of the material itself and the ways it ‘wants’ to be used. Through these practices and others, we can explore, and redefine the notion of ‘contemporary cob’.
Curious about contemporary cob building? Interested in seeing if this unique material might be a good fit for your new construction or renovation project? We are looking for opportunities to explore contemporary uses of Cob in Portland, Oregon and throughout the Pacific Northwest. Contact us for a free design consultation.
SOURCES - Weismann, Adam, and Katy Bryce. Building with Cob. - Evans, Ianto, Linda Smiley, and Michael Smith. The Hand-sculpted House. - Elizabeth, Lynne, and Cassandra Adams. Alternative Construction. - Lehm und Feuer | http://www.lehmundfeuer.de/