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Strawberry Fields Eco Lodge – Update: Cob Oven

Editor’s Note: As many of you will have noticed, Alex has been making some great practical updates on the work going on at the Strawberry Fields Eco-Lodge. Below is yet another little update on the practical application of permaculture in southern Ethiopia. In addition to the Steve Cran Training of Trainers course, the PRI’s Rhamis Kent will be making a May 30 – June 11, 2011 Permaculture Design Certificate course at Strawberry Fields in Ethiopia. Both of these courses are worth some serious consideration.

Another structure we built in the last couple of weeks was a small cob-oven. This is a great thing for our project to save on fuel wood consumption and allow us to make more kinds of food, like pizzas as well as baking loaf-bread rather than only flat bread which we currently make.

The oven was designed by Emily from the US who is our local Peace Corps volunteer and Asaf an Israeli volunteer who stayed with us for a couple of weeks.

Asaf did most of the construction work, helped be Mehdi from Morocco, but plenty of others mucked in on bits and pieces. During the construction we discovered that mixing gypsum with the local clay makes fine bricks that don’t crack at all, which is going to be a useful tool for further construction on the project which will save on using timber for construction.

The first part of the construction was the base which is a terrace, filled with sand/gravel/stable earth. This is then covered with a layer of clay mud into which glass bottles are embedded. These act as insulation to reduce heat loss into the base from the oven.

Over this layer clay bricks form the base of the oven. On top of this base a sand-dome is shaped. This is a sand castle which is formed to shape the cavity which will be the chamber of the oven. This is then covered with wet news paper to protect its form. A layer of nearly pure good-quality clay with a small amount of grass mixed in to bind it is then moulded over the paper layer. This is the heat-proof inner skin of the oven. Depending on the design of the oven a chimney can also be added at this stage, which Asaf did using a steel-sheet tube that was embedded in the clay-mud. Over this inner layer goes an insulating layer, which is a mix of mud and straw that contains a lot more straw. Finally an outer protective layer goes over this, which is again more clay-heavy, that protects the oven from the elements. A corrugated iron-sheet roof will protect the whole oven from the rain, and work-surfaces and shelves were artistically worked into the design. Nice work guys, thanks a million!

5 Comments

  1. Hi guys

    Does anyone who has built and used a cob oven still think that they are efficient with wood? I’ve helped build a couple and have cooked in both of them, but my experience has been that they take a fair chunk of fuel for the amount that you can actually cook in them. Maybe I haven’t spent enough time refining the art of cob oven cooking, or maybe they’re a form of sustainable living dogma. Not sure.

    However, I have to say that if you have some good tunes and good friends, it’s a lot of fun stomping in the mud and building the thing.

    Cheers, Cam

  2. Does anyone know how to incorporate a bio-char stove to heat such an oven? I would like to have such an oven made for a subsistence farmer that I know. I would like to create the soil amendment while using the heat to produce bread, or even pizza. At present, local farmers are simply burning field waste in open fires. The occasional pig roast is also over an open fire. I fear that the resulting smoke is a significant component in the low annual rainfall that this region has been experiencing.

  3. Do yu still need volunteers in you’re project? I’m very intersted.
    Can be available from May 2012.

    Thanks Hilde D

  4. About to embark on a pizza oven , and am thinking of using of using a rocket stove under it with the baking chamber as part of the combustion exhaust system. My theory being that i would end up with yummy smoked pizza …. or possibly charcoal…Was wondering if anyone has tried this?and can give me some pointers . :0)

  5. Great idea and information. With some minor modification this would work as a ceramic kiln too. Thanks for posting.

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