I have been making earthen ovens for over twenty years now. I made my first one in 1991 when I was working with architect Nader Khalili at CalEarth in the Mojave Desert. We were making a lot of adobe bricks at the time (friendly Persian-sized ones – 8”x8”x2”) and also building domes of regular fired bricks. I’m not sure what got it into my brain to make an oven, probably an old picture of the ovens at Taos Pueblo. One day I made a round foundation of adobe bricks in a mud mortar bed right on the ground, then hammered a string in the middle and used that as a guide to lay up a dome of the half-sized bricks. I then covered that with a mud plaster. I don’t remember if I made a chimney hole or not. I made it big enough to fit a big roasting pan I found at the thrift store. I learned that this is good way to size your oven (and especially your door!). I also made a cob door reinforced with a piece of metal from an old patio chair. For my first thing I decided to make a turkey (!) I made a big fire of construction scraps, and when it burned down to coals I put the turkey in there. I put the adobe door against the opening and sealed it all up with mud. Ooooo. Now the wait… Four hours later, yum! Best turkey I ever had. Used it lots for a year, and learned to make bread in it. Bread is the true test of an earth oven baker, in my opinion. I burned my eyebrows a lot, and it was a pain to bend over, so I swore to make my next oven higher off the ground. I don’t have a photo, but I did do a self-portrait of myself with the oven. I’ll have to find that and scan and post it later.
I made my next oven when I was in South Africa in 1994. Why I was in South Africa is another (much longer) story, but the gist is that I was there designing and building at the Tlholego Development Project, a teacher training center for permaculture and natural building. I had designed a round outdoor sitting area of earthbags, and an earth oven just wanted to be there. The local ladies were already using the center of the sitting area to do open fire cooking with the cool three-legged cast iron pots they have down there. So, I taught some of the local guys how to make an oven based on my previous experience. A few years later I taught I course at Thlolego, and the course coincided with Thanksgiving. You know what comes next – in the effort to spread goodly American culture, we had Thanksgiving with all the trimmings, including… Turkey! We made six of them… a solar turkey, an earth oven one, and a couple in the regular oven in the farmhouse. They all turned out good. The photo shows my daughter Taya in the cooking area when we visited in 2004.
It was not until 1995 that I had the chance to meet another earth oven aficionado, and that was none other than the famous Kiko Denzer. We met at the 1995 Natural Building Colloquium at the Black Range Lodge in Kingston, and I learned from watching him make a beautiful oven with spread-wing bench. I had the chance to cook in that one a few times, when later I moved to the Lodge. I think I helped replaster it too. Another lesson: it is good to make a shelter over your oven.
1n 1996 I was invited to Nova Scotia to teach a series of natural building courses with Bill and Athena Steen at the home of Kim Thompson, a local straw-bale and natural building advocate. My work there was to build the earth oven shelter of gravel bags, straw bales, earth plasters, and a roof of local timber for the “Quebec-style” earth oven built by Bill and Athena. This type of earth oven is unique because of its shape, and was different than others I had made. It had no chimney, was oval shaped, and had a relatively low roof. I real “aha” moment came when I saw that they used a sand form to create the support for the cob. This was dug out later. Brilliant. When I learned later about how well this oven fired, and even more, how it baked, I was sold on this shape. The basic lesson is that if an oven is too big, it does not bake efficiently, and that the interior shape of an oven (and the relationship to the shape/height of the door) is crucial to how well it works.
I first was exposed to a barrel oven when I spent several months at Gaia Ecovillage in Argentina in 1998. This was an intriguing device: a 55 gallon barrel held in place by brick ends with a brick vault built over it. It featured a firing chamber beneath and a small gap of a few inches between barrel and brick vault leading to a chimney on top. L brackets were welded inside to take specially constructed baking pans. I really liked the detail of adding several inches of sand at the bottom of the barrel to hold some thermal mass. We created a nice earthen plaster to cover the oven. We had some really nice food out of this oven, and I was impressed by its efficiency and ease of use. I remembered this design later, when faced with creating an oven for a fuel-starved project in South Africa (more on that later). Editor’s note: find out more about barrel ovens….
In 2002 I was living in Sonoma County on an organic fruit orchard. I held a series of workshops there, and decided on building an outdoor kitchen. I realized that I wanted a real kitchen, with a sink, counters, stove and a place to sit. So, I designed it with all of these. We an oven base and seat base of gravel bags, which we then covered with cob. We built up the backs of the seats with cob. In the workshop was an amateur blacksmith, who offered to make an oven door for us. We cobbed in a sink, and the kettle part of a Weber grill, and made a counter by spanning cob columns with bamboo and cobbing over that. I used the amazing sand form method, and creating a cob layer, as well as an external layer of straw-clay (I thought insulation would be good). I had heard different schools of thought about when you should take out the sand form: 1. Right away and 2. After a long time. Being the impatient sort, I went with #1. Oops. Wrong choice. The inner layer collapsed. Wahhh! But the external straw-clay layer stayed, and luckily was more clay than straw. So… we used it anyway. I ended up plastering the inside, and lived with having a bigger oven. I assume most of the straw has now burnt out, but it ended up working fine. A key thing I started to do with this oven was to eliminate the ash/coal removal process. I did this by loosely piling fired bricks inside the oven. The hot coals and ash would sift down between the bricks, and I would cook in cast iron pans right over the coals. I refuse to mess around with hot coals again. This ended up working really well, as it also raised the cooking vessels into the hotter part of the oven, while providing cooking heat from below and good radiant heat from the cob roof of the oven. While it looked great, and was convenient, I don’t think I will do a metal door again: it lets out too much heat.
A couple of years later, I made another edition of the outdoor kitchen based with students from New College. Used all my lessons: counter height, sand form, insulating outer layer, Quebec-shape, nearby counters and seating and added a new twist: a pot boiler designed at the chimney hole.
I also held a workshop at my home, where we made an entire cob oven in a weekend. Phew!
South Africa called again in 2004, and I went over for a series of workshops and design sessions designing a children’s village in a rural town outside of Pretoria. I was asked to design an outdoor kitchen, and remembered the high efficiency oven I saw in Argentina. I created a design based on my memory, made some sketches, and when a colleague of mine went over, he built the oven as part of an outdoor kitchen and eating complex. From all reports it works great. I also designed a ground rocket stove for use with the cast iron cooking pots, but I never heard how that worked out.
In 2007 and had the opportunity to design and build an outdoor pavilion and kitchen for a client in Healdsburg. I had a chance to do all sorts of cool natural building stuff on this project: super refined cob walls, roman style pebble floors, an outdoor sitting area, and… a cob oven. We decided to add a chimney, since this was a high fire danger area, and we didn’t want to have any sparks. I used all my tricks up to this point, adding an idea of using vermiculite instead of straw to make an insulating layer. And I had learned my lesson, and let this oven dry slooowwwwly. It turned out beautifully, and bakes well, too.
By this point, however, I had become somewhat disenchanted by earth ovens as I had built them, no matter how much I love building and cooking in them. In fact I cringe now whenever I see another wood oven workshop being advertised. The main reason for my change of heart is that most earthen ovens are incredibly wasteful of wood and heat energy. I have so often seen an oven fired for hours just to cook a few pizzas, wasting wood, and sending carbon dioxide and particulate matter into the air. As someone who is trying to save resources, this seemed untenable. Then I heard about this mad scientist down in Los Angeles, Ray Cirino, who was coming up with a super-efficient cob oven concept. I knew I was onboard. After some back and forth on the coblist, I got enough ideas for my next effort, which is currently under construction at a high school in Sonoma County.
For this project I am putting together all my features into my ultimate oven. Counter height? Check. Vermiculite cob insulation? Check. Quebec shape? Check. Pot boiler chimney? Check. But, now, with the addition of a firing chamber beneath the oven, and a metal baking shelf, I hope to create an oven that can be used to cook with right away, is easier to regulate, and is much more efficient with wood use. Stay tuned. I will be sure to send more information as we complete the oven.
So that is my story to date. I hope you have enjoyed it.
Note from the Editor: It has been gratifying to see the attention that this guest article has received…. If you have a story about making ovens, heating your home, working with natural materials or even something else you want to share, let us know about your story so we can work together to get it published.