Building with Natural Materials | The Cob Oven
How did you start building with Cob?
Here’s what Bryce had to say:
I first started building with cob 10 years ago on Mayne Island, B.C. in a 3-week long workshop with Pat Hennebery. I then spent the next 3 years working with Pat on different cob projects all over B.C .and went on to spend time with many other natural builders in different places to see how others were doing things.
What is Cob?
Cob is a name for a particular style of earth building. It typically consists of three parts sand, one part clay, and one part fibre—usually straw—which you add water to, in order to make a sculptable material that can be piled on a foundation to make a wall or an oven. Once it's layered up and dry, is incredibly strong and durable.
What are the benefits of building with cob?
The main benefit is that it can usually be made with very local materials, often the ground beneath your feet, with very few tools. It’s also a very creative, and flexible building material, and can be made into curves and arches, can be carved and sculpted, and is endlessly reusable (won't ever end up in a toxic landfill). It is also breathable, fireproof, bug proof, load bearing, and regulates humidity.
How long did it take to build your cob oven?
I usually build cob ovens in a workshop setting as a teaching tool to introduce people to building with the earth, and to form relationships with fire. The workshops are usually two days long, and I will usually put in another three to four days of work prepping the foundation, and finishing the oven.
Do you design it before you start or does it take form as you build?
I sometimes have a general idea of what I might want it to look like, but it usually will take form as it's built regardless.
Can you tell us a little about cooking in a cob oven?
The beauty of cooking in a cob oven is that it's a commitment, especially if you want to use it efficiently. Which you should, since it requires a fair amount of firewood and produces a fair amount of emissions to heat a wood-fired oven, which shouldn't be taken for granted.
It usually requires an oven full of wood and 1-4 hours to heat the mass of the oven. I always build ovens with chimneys at the front that act as a burner. So, I can cook on it, usually in a cast iron pan, while the oven is firing.
Once the oven gets up to temperature (800-900°f) you can start with high temp foods such as pizza, and pastries, coming quickly out of the oven. Then as the temperature drops, you can then plan loaves of breads, roasts, stews, and other slow-cooked foods as the hours pass. Often at the end of baking, I’ll put in apples, or something else to slow cook overnight because the oven will hold heat for many hours.
Cob is an ancient technique, is there any way for technology to help it become more popular?
It's mainly socio-cultural misconceptions and conditioning that keep things like cob from being widespread. It is fairly simple to incorporate modern technology—plumbing, electrical, etc. into a cob structure, but the standardized building industry makes it difficult to build things that aren't standardized, and that isn't easily engineered. Even though cob structures have a history of durability and ease of construction, that goes back thousands of years, and even though there are many modern examples of high-quality earthen structures, there’s still resistance to anything that falls outside the "norm" because the system isn't set up to allow for it. The construction industry is currently set up, and training people, to build an inferior building system, which contains tons of expensive, toxic materials, that’ll likely end up in the landfill in 20-100 years.
Is there anything else we should know about cob or natural building?
An important thing to know about cob is that it’s considered "thermal mass"—meaning it will retain heat and cold. This means, if you have a big cob house, you have a lot of mass to heat to keep it warm. This is ultimately less efficient than having insulation which will allow you to heat or cool the air or the mass of a floor, and retain that heat or cold by insulating it from the outside. Unless you are building a small structure, or are in a mild or desert climate, natural insulators, like straw bales or something called "light clay" (straw or wood chips mixed with clay slip) are a more appropriate building material.
The main aim of natural building is the appropriate use of resources. Instead of excavating and hauling tons of clay away from a building site, use it to build homes, other structures, or as natural wall finishes. Instead of importing insulation, and other materials from far away—who knows where—get straw from a local farmer, or timbers from a local mill. Build things to last, build small, or build something for many people to share in together.
What Does Keep Food Alive mean to you?
To me, Keep Food Alive, means creating and preserving food culture, supporting farmers and indigenous people to produce, develop, and provide a local terroir, and making sure it doesn't go to waste.
Where can we learn more?
We have resources on our website— dreamweaverscollective.org —I always encourage people to do some research, take a workshop, and seek out ways to connect with others to help rethink how we structure our structures. We will also be launching a Natural Building Basics online course soon!
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