We finally finished building our new and improved earth oven a couple of months ago. We tore down the old one and recycled it to make this one. To improve it, we added a brick arch and made the diameter 4 inches bigger. I'm glad we did since we are using it so much on our Farm Days. The arch is much stronger than the clay and protects the oven from accidental bangs with the pizza paddles or pokes from sticks of wood while adding fuel to the fire. I really like the larger size because of the amount of people we're cooking for. Sometimes I need to cook 45 small personal pizzas in it for our guests so I'm thankful for the extra space. We can easily cook 15-20 pizzas at a time or more if we work fast enough. We have to get those pizzas out quick because they're done in 3 minutes! The oven is well over 700*F!
Let me just say...I LOVE THIS OVEN!!! Not only does it work great, but we don't have to heat up the house on hot days. If we plan it right, we can use the oven for all of our meals on one firing. We usually build a fire in it early in the morning and keep it burning for 2-3 hours. The tremendous heat given off by the fire soaks into the oven walls and is stored there. I'm not quite sure how hot it actually gets with the fire going, but after we shovel out all the coals, sweep and mop the oven floor, stick an oven thermometer inside and close the door for 5-10 minutes, the measuring hand in the thermometer is WAY past highest reading of 600*F. I've heard some say it can get up to 750*F. Whatever it is doesn't really matter to me. All I know is that we can cook pitas or pizzas in there in about 3 minutes! And it's perfectly baked pizza too...nice crispy crust on the outside, soft and tender bread on the inside. Mmm Mmm! It also bakes THE BEST bread. What makes it so wonderful to cook in is the fact that it uses all 3 types of heat energy: conductive heat, convection heat, and radiant heat. This causes everything in the oven to cook evenly, which is fantastic! So I can cook several things at a time in my big and roomy oven and I don't have to worry about hot or cool spots. Fancy, expensive high tech kitchen ovens just can't beat that because they only use the first 2 types of heat energy. Not only does the oven cook evenly, but it retains its heat for a long time. If sealed properly, the oven can stay hot all day, all night, and can even be used the next morning (it can easily be over 250* F). It can do this because of the thick layer of insulation surrounding the oven walls and floor.
You might be wondering why or how we decided to build one of these. Well, ever since we first moved out to the country in 2004, I had wanted to build some sort of outdoor oven contraption to use during the summer months so we wouldn't heat up the house cooking meals. I didn't quite know what I wanted it to look like or how to build it even, but I thought we could use our leftover bricks (from building our house) to construct it. We even poured a concrete slab in the back yard for it to sit on. I had lots of ideas and plans drawn out on paper. And I was about ready to begin the project when I thought that maybe I should look on the internet to see if there were any better ideas out there. And that's when I found what I was looking for... beautiful pictures of dome shaped earthen ovens. I read about them and decided that was what I wanted. Something made from our land, from our own soil. Something simple yet beautiful. Something useful as well as inexpensive to make. That's my kind of project!
***The concrete slab we poured for the oven and the leftover bricks from our house are now being used to make a brick grill/smoker directly across from the earth oven. We're in the middle of that project now. I'm really excited about that too!
Here are some pictures of the building process from start to finish.
The foundation has glass bottles imbedded in sawdust and clay for insulation. This keeps the heat from escaping through the floor.
We put a brick form around the outside so we could pack the oven mix on top of the bottles.
Here is Sierra shoveling the oven clay mix. It is 4 parts sand to 1 part clay with some water added to make it stick together.
The oven mix is about 3" thick.
Here I am sifting sand onto the now dry clay mix. It needs to be about a 1/2" thick and level.
Here's the layout I drew of the firebrick floor. It's kind of tricky to get it just right.
The bricks need to slide down slowly and rub the brick next to it to get a tight fit.
Once the bricks are in place, don't wiggle them. If they aren't level tap them down gently with a rubber mallet. They need to be completely smooth and level. Rub your fingers on them to make sure there are no high or low spots.
Next I found the middle and marked it with a pencil. Then I traced the diameter of the oven with the pencil and then later with a permanent marker so I could see it well.
Now I'm deciding on the shape and size I want the brick arch to be and tracing it on cardboard. You don't want the door to be too big because it will let out too much heat. But if it's too small you can't fit cookie sheets and large pots. I measured all of my biggest pans before I drew this out. The kitties enjoyed helping me with this part of the project.
Next, Creg made a wooden form for the brick arch. You need to make it an 1/8" too short so you can fit wooden shims under it. You pull those out after the arch is finished so the form can come out.
I found some rocks to wedge between the bricks. They stay in there even after the clay/sand mortar is filled in. Be careful not to dislodge the rocks.
Now I'm stuffing in the mortar and packing it tightly with the back of an old spoon.
Now it's time to make the sand form. This determines the shape of the oven walls. You want the first 4" to be built straight up, then you can start curving the sand to make an egg shape. This is where you follow the marker drawing on the brick floor. Pack it hard and tight. The sand needs to be damp, but not too wet. The shape needs to look right. Back away from it and look at it from all sides to see that it has a nice shape.
After its packed tight with your hands, use a 2x4 or 2x6 to smooth it out. Rock it back and forth checking the shape often. Be careful not to hit the brick arch. I did and it messed up my arch. Grrr!!! It needs to be repaired now because the middle bricks are loose and sagging.
After its all nice and smooth and beautiful, cover it with a couple of layers of wet newspaper. Tear the paper into strips so there are no wrinkles. ***We forgot this step on the first oven we built and that's why we are redoing it. If you forget this step, you can't tell where to stop when you dig out the sand after the oven walls are built. I dug into some of the oven walls and it caused it to crumble onto our food. When the big chunks started falling we had to tear it down and start over.
Now the kids are mixing the clay and water. This is the fun part....getting DIRTY!!!
The sand is already measured out on the tarp and Sterling is shoveling the clay soup onto it. (See baby Skye helping!) This is the mixture for the oven walls. 4 parts sand/ 1 part clay/ enough water to make a stiff mixture.
The best way to mix this stuff is to dance on top of it for a while, roll it over by pulling the tarp, and then jumping on it some more. Keep on doing this until it is well mixed. **Tip...the more the merrier! And the easier it is to pull the tarp.
You don't want this mixture to be too wet. If it is, it won't pack well. The bottom part will ooze out because it's not stiff enough to withstand the weight of the top part.
Creg and I are building the oven walls. You have to be careful not to push on the sand form. We put the oven wall mixture on about 4" thick and packed it firmly against itself, not against the sand. Because of the wind, we had to put an old sheet on top of the newspaper to keep it in place.
Here we have finished the oven walls by hand. Now it needs to be packed firm with the 2x4 and smoothed by rocking it back and forth. Stop when the shape looks right. In hard to reach places like the bottom and around the brick arch use the back of a spoon to smooth. When finished it should look as smooth as the sand form did.
If the walls are quite stiff and firm, its time to dig out the sand form. Do a little at a time making sure the walls won't collapse. And be careful when you get to the ends. Don't poke the oven walls or dig too deeply. After all the sand is out you can remove the newspaper or just let it burn out later. I wanted to smooth the inside of the walls with the back of a spoon, so we pulled out the newspaper. Our oven is quite a bit bigger than last time and I didn't have to crawl inside that one. But here I am squirming like a worm to get inside. That was a weird feeling! If you are scared of tight spaces, don't try this!!! The entrance was so small I had to wiggle just a certain way to make it inside. It was quite awkward. I put a lamp inside with me so I could see what I was doing.
Now we are slowly drying out the oven walls by building a series of small fires. See how pretty the brick arch looks. It doesn't have any black soot on it yet.
Wait until that layer dries some before adding the next layer which is the insulation layer. It is made of clay soup (clay and water) and sawdust. This layer is 4-6" thick and it allows the oven to hold its heat much longer than if it wasn't there. It works so well, that you can touch the top of the oven when it's well over 800*F and it barely feels warm to the touch. My oven will be over 250*F 24 hours after a firing if I keep the door sealed shut. Here we are packing the insulation on. This layer doesn't need to be packed tight. You want it to be a little loose since its insulation. Supposedly the sawdust eventually burns out and leaves little air pockets where the sawdust once was.
After this layer is finished you can add a third layer which is like the oven mix layer. This is the layer you can decorate to make your oven look pretty. I don't have any pictures of us working on this layer.
If you want complete directions on how to build an earth oven, read Kiko Denzer's book BUILD YOUR OWN EARTH OVEN. That is where I got all of my information. He gives step by step directions.