How to Build an Earthen Oven for Free

Hinako and Tsugu share how they built an earthen oven with natural and secondhand materials for free. They built this oven to be more self-sufficient and source their own energy. This video not only shares their example, but teaches you how you can do it as well.

Hinako and Tsugu in Japan are a wonderful example of people striving to live a more sustainable life. They are repairing an old Japanese style house with natural and scrap materials. They have a composting toilet, grow and forage some of their own food, preserve and ferment the abundance and have installed solar panels to create electricity.

Transcript: The following is a transcription of How to Build an Earthen Oven for Free.

Today I am going to introduce you to a really inspirational and lovely couple. Their names are Hinako and Tsugu and they are located in Japan. They are going to introduce you to how to build an earthen oven out of natural materials and second-hand materials for free. This is a way to cook sustainably using resources that are growing locally and to get out of the technological system and live sustainably off of the land. I’m really excited to introduce you to them. Here they are.

Hi, my name is Hinako and I’m currently living on a tiny island in the southwest part of Japan, together with my partner Tsugu. We have been gradually transitioning to a more sustainable lifestyle since last summer. One of the big changes that we have made so far is this earthen oven. We used it to bake homemade breads in a little oven before, but we felt like moving one step forward to be more self-sufficient, especially on energy use by making use of nearby firewood.

Today, we are going to share with you how we created this wonderful earthen oven for free, without buying anything, with all of the materials found from the island to be as environmentally friendly as possible. What we used was basically soils, rocks, and water which everyone can easily find just around you. We also used repurposed materials such as broken roof tiles, which we got when we repaired our old Japanese style house, and any kind of bottles that were once used and about to be thrown away.

The most essential component is the soil. It’s said that a mixture of 60% of clay and 40% of sand is ideal for a strong and heat-resistant oven. To find our good soil, we did two kinds of tests, soil inspection and fireproof inspection. In the first experiment, we put collected soil and water in a bottle, shook it, and left it for a day. On the next day, the soil was separated into layers of clay, silt, and sand from the bottom. We knew how much clay and sand were in there, and luckily we had an almost ideal mixture.

In the next experiment, we made a little dirt ball with the soil and water, dried it, and fired it for about half an hour to see if it is durable to high heat and did not make any cracks. We ended up finding our ideal soil at a nearby mountain where a tree had fallen from its roots.

Let’s move on to how we built it part by part. For the foundation, first we made a 1 square meter of square wall with rocks collected from a beach just behind our house and filled any spaces with a mixture of the soil and water. Then, we filled the center space with the broken roof tiles to make a stable and heat-insulating foundation. You could use anything for this filling such as stone, sand, or even scrap materials as long as you fill the space. Last, we covered the surface with the mud. This will be the floor of the oven. Make sure the mud is smooth enough, without stones or whatsoever, to prevent it from cracking.

In order to build the 1st layer, we made a wet sand castle with our garden’s sandy soil first. We decided on a size that was large enough to bake a pizza in. As far as the inner height, the height of the door should be 63% compared to the inner dome height so that the heat can effectively circulate inside and rapidly warm up the oven. We also placed a wall at the door and covered the surface with wet newspaper so that the castle would stay in the same shape and it would be much easier to take the sand out later since it will not stick to the 1st layer.

Now was the fun part, stepping on and mixing the soil with water until it became a nice and firm consistency which held together well, but was still moldable. Once the mud making was finished, we shaped it into bricks about 8cm wide, and built them up. It’s important to make no air spaces for less future cracking. Also, making little holes on the surface with fingers helped the next layer to stick to it much better.

On the next day, we continued to building the 2nd layer. This time, we needed to add some binding materials, such as straw or dried grass, to give this cob layer a lot more strength than the inner layer. However, we decided to use just the root soil since it already had straw in it. Again, same as the inner layer, we mixed it with some water, shaped it, and built it up. By the way, it’s not something you have to do, but we created an air-layer between the 1st and 2nd layer with the bottles to create a better heat insulation. We also placed a chimney here which someone gave us, not only for letting smoke out but also for boiling water with a kettle on. We decorated the surface with beach glass and did some drawings, as well.

After letting the oven dry for about 2 weeks, avoiding direct sunlight and rainwater, it is time to take the wall and sand out. We added some more cob at the door to make a rounded opening for a stronger oven. Once we checked that the oven had firmed up enough, we started warming up the oven gradually from low heat to medium heat. I think we fired it for about 6 hours on the 1st day, and 5 hours on the second day, and it was a day when we had a pizza party with our community friends! The first pizza baked in this oven was just so amazing.

One of the great things about this earthen oven is that we can easily repair it. It’s normal that a cob oven gets cracked after several uses. We just need to apply a bit of mud, let it dry, and it’s ready to be used again. Also, even though this oven becomes super hard and durable, like a rock, in the end it’s still water-soluble, and needs to be protected from the weather with a roof over it.

So how do we use and cook in the oven? Well, we start with a small warming fire with leaves and sticks right inside the door. Then, add some more thin wood and push that to the back inside. And gradually add thicker wood, just like building a tower. We usually use 8-10 thick pieces of wood for a one time bake. When the oven gets hot enough, we see less smoke coming out and the walls will change from black to white as the soot becomes ash. Then we close the chimney. From then, it takes about 1 hour or so depending on the wood and weather. The drier the wood is, the easier to get ready.

For pizza, once the oven is heated up, we push the coals to the sides, clean the floor with a wrung-out towel, and start baking. A peel makes it easier to put the dough into the oven. Turn the dough around about every 30 seconds or so. A crispy pizza is ready to go. As for bread baking, once the oven is heated, take some coals out, clean the floor, close the door, and wait for about 5 minutes to let the oven cool down a little bit. For smaller bread, we put them on a small metal plate, though usually we just bake our bread directly on the floor, and there will be no sand on the bread. For better bread, we spray some water on the dough right after putting it in the oven. Depending on the size, the bread is done after 10 or 20 minutes of baking. During the time, turn the dough once for an even cook.

One tip for using the oven efficiently is to start baking with something that needs high temperature, such as pies and pizza, then shift to bread or cookies, and you can also dry herbs and fruits last.

We hope you enjoy creating your own earthen oven and happy bread baking!

I find Hinako and Tsugu to be a really lovely and inspirational couple, and it’s so inspiring to see all they are doing to live a more sustainable life. I really hope that you found them to be inspiring and that you learned from this video. If you did, make sure to subscribe to their channel. The links to follow them are in the description. Make sure to subscribe to this channel, as well if you haven’t yet. I have a lot more educational and inspirational videos already filmed and many more to come. If you want to spread this message, make sure to share it, to like it, and to comment to help get this out to more people. I love you all, very much. I’m looking forward to seeing you again, real soon.