Clay, or “earthen” ovens are simple in design. Using wood to fire them and the insulating properties of bricks and clay to absorb and then radiate heat, you can cook anything in an earthen oven that you could cook in a conventional oven. One easy and common thing to cook in an earthen oven is pizza. If you’ve ever had wood-fired pizza, you know how delicious that is, so with those thoughts in mind, some simple tools and materials and then help of a few friends, you’ll be chowing down on delicious treats in no time.
How to build a clay oven in your garden?
An invaluable resource for this is Kiko Denzer’s book Build Your Own Earth Oven.
For a simple, one-layer oven, you will need:
- Clay (from subsoil. Do not use topsoil).
- Sharp sand to mix with clay
- About 28 firebricks (standard bricks do not retain heat as well and have a tendency to break).
- Material for foundation (this can include standard bricks, wood, or urbanite made from old concrete pieces)
Materials to build a basic roof to cover your oven
- Construct the base. It should be sturdy and at the height you want to work on. A solid wooden base will work, or anything that is load-bearing and is at least the dimensions of your oven.
- Make a square with one layer of bricks fit firmly together. Draw a circle around the inside of the bricks, blocking out the working area for your oven. You’re now going to create a sand form for your oven.
- Make a mound of moist sand to the diameter of the circle you laid out. You can use a flat piece of board to mold this sand until it’s the proper width and height (your dome height should be about 75% of the oven’s diameter).
- Make your clay mixture (this is called “cob”), combining about 75% sand with 25% clay on a tarp. Stomp the mixture together until it’s unfiform, getting clay clumps out. Roll the mixture over using the tarp and continue to mix it. This is where a few friends come in handy. Add some water and roll the mixture around, stomping it some more.
- To test consistency, we’ll check to see if the cob is crumbly and can maintain its shape. These are tactile tests. Add a small amount of water to a sample of your mixture. Squeeze it in your hand. It should make a grinding sound. If you don’t hear that, add more sand. Then form a snowball-sized ball with a sample of your mixture. Drop it on the ground. If it crumbles, add more clay. If it flattens, add more sand. It holds its shape, it’s ready.
- Apply the cob to the sand form carefully, using small handfuls and pressing down, but not enough to mess up your form. The oven should be at least three inches thick. Leave room for a door that is wide enough for food to pass through. The opening should be about 60% of the oven’s total height. Use the board you used on the sand form to whack the cob into shape, or tamp it. Smooth it with your hands.
- You may choose to add an insulating layer from here, or a finishing layer. Give your oven a couple days to dry, build a simple roof over it to protect it from rain and remove the sand.