Sustainable for a Future

Cob Oven: Part II: The Actual Oven


This entry is part 2 of 3 in the series Cob Oven

Building the Oven was a lot of fun. We used a 3:1 ratio of sand to clay in our mix. The first layer was only sand and clay and as you can see below we kept our boots on when mixing these batches. That is because the clay was from near our spring and it is extremely rocky. Plus it was March so cold clay on feet is not so fun.





After waiting a day or two for the first layer to firm up we added our second layer which was clay sand and straw. The same ratio of clay to sand and several handfuls of straw for insulation. It has only been about 8 months but I do not recall if we decided to go for a third layer. We might have or might not have. This is a good time to bring up what I think is largely ignored on a lot of these tutorials. It’s leeway. The fact is, in my experience it seems like no matter how you do something, it’ll probably turn out alright. Of course this might seem like the worst advice ever but, the fact is as long as you stick to the basics there is a lot of play room. And, there is the submit-to- stupid-error factor too. But don’t be scared, just do what you can and it will usually work!

Whether we did three layers or 2, the oven cooks things, it get’s hot and retains heat and cooks things…the end!



This is what the oven looked like after just the first layer. What we did was we piled up sand in a mound and covered it with wet newspaper to create a form. Essentially, you want to create the cavity where the fire and food go in. So it is important to have a good idea of how big you want your interior. This is dictated by the amount of room you have on your foundation and how tall you want your oven to be. We kept it relatively small so that it wouldn’t take a tree’s worth of wood to cook one pizza.



Above you can see Daniel cutting the hole for the door. We decided to build the door first and cut the hole to match it. You can also see that the second (or third) layer of cob is in place, it is much thicker and smooth too.

In fact, now that i remember more, we did use three layers. The third layer is made from sand, clay and a sawdust-like substance called kenaf. We used kenaf because it was graciously donated to us by Grace Klinger friend and benefactor. Kenaf, like sawdust, absorbs a lot of water, so this final layer ended up like a smooth peanutbuttery consistency. We also used the same mix for our art layer. We added in probably 5 or 6 handfulls of the kenaf. It is both insulatory and less pokey as straw. It worked really well for us.

The door itself is made from a sturdy slab of wood, procured by Jayden Steinke. It’s shape was made by the process of cutting out small notches in the wood and then chipping them away. We had to do it this way since we do not use power tools.

In the next article the finished product is revealed! (Dun Dun Dun)

Series Navigation<< Building a Cob Oven: Part I: The FoundationCob Oven Part III: Final Product >>

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