Our Earth Oven

This is our earth oven. It was built according to the technique described in Kiko Denzer's book Build Your Own Earth Oven. Before we built this oven we did very little baking. We do have a small, propane camping oven, but the trouble of dragging it out and hooking it up was just too much. Now we bake at least once a week, making bread, desserts, pizza, etc. all in the same day. It is wood fired. The main building material - clay soil - came right from the ground the oven sits on. Below you will see step by step photos and explanation of the process. Did I mention that building it was just plain fun?!? Everyone should have one!

We started by digging a hole two feet deep by five feet in diameter. This was so that the oven's foundation would be below the frost line for our area. The foundation was built from used concrete blocks and filled with gravel.

The foundation was built up to approximately waist height for easy access.

Next came the subfloor and insulation to keep heat from going out the bottom of the oven. The insulation consisted of glass bottles set in a mortor of clay mud and sawdust. In the center we poured a thick layer of clay mud and sawdust as a heat sink to absorb and retain the heat from the floor. All of this was smoothed out by a bed of sand, tamped firm.

Then came the hearth floor. This was made of fire brick, carefully layed out on the smooth sand surface.

The doorway is an arch made of fire brick...which stands like magic! Actually, we have had some slippage after firing the oven multiple times. No bricks have fallen, but they are threatening too. Still, it has worked amazingly well. I was dubious that it would work at all.

The inside of the oven is, of course, hollow. But, before you can have hollow, you have to have solid. So, next you build a form out of sand, exactly the way you want the inside of your oven to look. You are supposed to spend a lot of time making this part especially neat because the more meticulous you are with the shape of the void, the better your fires will burn. Plus it's a lot of fun, like making sand castles.

The oven walls consist of four layers:

• Thermal Mass - This layer, the innermost one, is made from a mixture of clay-mud and sand, 4 inches thick. Very dense, acts as a heat sink to absorb the heat and slowly release it while baking.
• Insulation - The middle, insulative layer is a 4-inch thick shell of clay-mud and sawdust.
• Sculptural - This layer is a mixture of clay, sand and straw. The straw acts like rebar in concrete to provide structural support. This layer is as thick as you want it and mainly serves to flesh out the oven and give it shape. You can be an artist with this layer and make your oven into whatever you want.
• Finish Plaster - This layer is optional but makes gives the oven a finished look and can be colored with pigments if desired.

After the first layer is up and dry enough to hold its shape, the sand form can be removed, leaving the hollow oven interior. At this point you can bake in it, but it won't hold heat as long as it will when the other layers are on it. Drying can take a long time. Lighting fires in the oven helps dry the layers out. This photo shows the insulation layer going on.

We made the clay mixes by dumping all the ingredients on a tarp and stomping away! It makes for muddy feet and sore legs.

We sculpted our oven loosely into the shape of a snail or a cinna-bun. Neither one of us are sculptors, but we had fun playing with it. We have yet to put the finish plaster layer on. There are a few cracks to patch before we do. We have already put it to much use baking, though. The oven has become the centerpiece of a larger, outdoor kitchen.