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Build Your Own Earth Oven

Quick! before summer is over and there is a chill in the air, you MUST make an earth oven. Also known as a cob oven, ours is made entirely from the rock, soil and sand on the cottage property. The only items purchased were the fire bricks, woodstove pipe, and a bale of straw. Our design is based on the methods outlined in Kiko Denzer’s book, “How to Build an Earth Oven”. Invite some friends over and make it in a weekend.

Flames seen shooting up into the back of the rocket earth oven via the stove pipe.

The beauty of this oven, is that Hubby brilliantly merged a rocket mass heater into the design. Instead of the traditional way of building a wood fire on the oven floor, the fire is located below in a burn chamber. The rocket mass heater burns fuel more efficiently, using very little wood. A whole day of cooking used only four, medium-sized hardwood logs. Once the fire catches, it burns really clean, there is no smoke or creosote. You are left with white ash. Nothing is wasted. The black soot you see is from earlier trials of getting our fire going. After a couple of days of getting used to our oven, we’ve finally learned to cook by feel.

Hickory chips soaking, you can see the steam leaving the oven as the earth is drying.

I purchased Kiko Denzer’s book, a few years ago, where it sadly remained at the bottom of our cottage “To Do” list. My one regret is, what took us so long? It’s the greatest thing ever and has become the heart & soul for gatherings large & small. It turned a space that wasn’t well used, into a popular place to linger: stoking the fire, chopping wood, sipping wine, picking basil, playing guitar, and of course stuffing our faces. It makes the simplest pizza taste like the best pizza you’ll ever have in your whole entire life. Okay…so it also happens to be topped with fresh San Marzano tomatoes and basil growing just a few feet away. At 700•F, it takes 2-3 minutes to bake a pizza. From field to table in less than 5 minutes. How great is that? I’ve added a few more garden beds to grow a larger selection of pizza toppings.

Italian spicy sausage (from my favourite butcher), potato, tomato and cheese pizza.

You can have cinnamon rolls on demand by making up a few batches and
freezing them individually and storing in x-large Ziplocks.
I even freeze the icing, portioned out in smaller Ziplock sandwich bags.

Besides pizza, bread, cinnamon rolls and cookies, we’ve also been experimenting with roasting and smoking meats. Verdict: pork tenderloin – melt in your mouth deliciousness! Rack of lamb – succulent! Chicken – crispy like Peking Duck! All with a subtle hints of wood-smokey flavour. Baked potatoes, roasted potatoes and beets were also very good. It’s a continuous process: stoke fire, put something in oven, put something in mouth. Help! One can’t have an empty oven when it’s burning really well.

The first thing to do is test your dirt for strength and shrinkage.
We are lucky to have perfect dirt, the ratio of sand and clay holds together without shrinkage.

To do the shrinkage test, mix the dirt with water to form bricks at least an inch thick. I used a 9 x 13-inch cake pan.

One-inch increments were marked to measure against. Lucky for us, the bricks dried without any shrinkage.
No shrinking means a strong soil mix.

Start with a solid foundation that will not move and keep your oven off the ground and dry.
You don’t want any moisture wicking up from the ground causing your oven to crack.

Hubby tests the draw of the fire before continuing. What you see is the burn chamber for the rocket heater.
There is also a cleanout exit at the back which you can’t see. The pipe makes a sort of a “T” join.

Heat will rise and exit from the top right into the oven. It is mostly steam and very little smoke that exhausts out.

Continue to build your foundation; the inside is filled with old bricks from a neighbour, surrounded by flagstone from our hillside.

Level with a layer of sand in preparation for the fire bricks used to line the oven floor.

Kids making mud.

The light coloured bricks is the oven floor. Wet sand is mounded on top to make the form for the domed walls.

Making clay potatoes for the next step.

Wet newspaper is applied to the finished sand form.
The first layer of mud (thermal layer), will hold most of the heat from the oven.

Thermal layer complete! The mud was a bit on the wet side and started to sag at the bottom from all the weight.

The first layer is roughed up for the second layer (cob layer) to stick to.
The door opening has been cut out, exposing the sand form inside.

Cob is a mixture of mud and straw. It provides both strength and insulation.

The girls help with the mixing of the cob. The cob does a fine job insulating, and is remarkably fireproof.
Inside temperatures can reaching 1200•F, but the outside is barely warm to the touch.

Cob logs are rolled with the help of heavy plastic.

Press down, rather than pound against the sides.

There is nothing more satisfying than creating something with your hands.

A final finishing layer of mud is troweled on.

Scrape out the sand once the cob has had a chance to stiffen up.
Remember the newspaper layer? Keep scraping till you reach that layer.

The door was cut out of a really thick piece of old-growth pine and lined on the inside with a sheet of galvanized metal.
It’s attached all around with screws and washers in between to create an airspace.
This helps to keep the metal from heating up the door. I love the driftwood cedar door handle, rescued from the lake.

There are buildings made out of cob that are still standing after hundreds of years. Maybe this earth oven will too.

 

Nikolai - Wonderful!

Thanks for sharing :)

Deirdre Pickford - this looks so amazing jill and kevin – i bet the food tastes wonderful!!! i bet you’re going to test out a turkey in there in a couple of months…the smells must be heavenly!!

Jill - You read my mind Deirdre, I made sure the turkey pan would fit through the door!

Janet Eastwood - Fantastic!! Can you bake bread too Jill?

Jill - Absolutely! I’ve baked a cheese loaf, and garlic loaf. The first try were a little smokey, but practice makes perfect…and unfortunately bigger hips!

france Simard - wow! this is truly fantastic! congrats to you all for this outstanding lovingly made earth oven! It is a thing of beauty!

jill Farber - mazel tov
looks awesome!

Growing Garlic and a Baba Ghanoush Recipe | Eat Boutique - handmade food giftbox, homemade, homespun, gift basket, food that hugs you back - [...] oil and roasted.Roasting caramelizes and sweetens both eggplant and garlic. These were done in an earth oven, which added a nice earthy smokey flavor.Mash peeled eggplant and garlic together with some fresh [...]

Paulo - Parabéns. Vou tentar fazer um igual aqui em casa.

Jill - Paulo – Que parte do mundo você é? é um projeto divertido. boa sorte!

Brendan - Your family does such wonderful things! :)

Adam - This looks great! I was hoping to find some confirmation that cob oven could be fired with a rocket-stove – but this is straight out inspiring! do you have any additional shelter to protect it from the elements?

BTW the galvanized door lining will off-gas toxic metals in to the oven at high temps, perhaps heavy duty aluminum foil or some stainless steel would be better?

Jill - Hi Adam! I did not know about the galvanized metal! Thanks for pointing that out! Is that your house that was built in Rwanda? Amazing!
Yes, the rocket stove heats up the oven pretty fast, but I find that the floor does not get things crispy unless I build a fire right in there like a traditional wood oven.

shaelee - Hello, are you happy with the rocket combo? How long does it take to heat up? I am hoping to finally build one this summer after years of meaning to! Thanks for saying I MUST!

Tomato Basil Jam - [...] of shrimp. We’d laze away the afternoon cooking all sorts of stuff in her handmade outdoor earth oven or roll up fresh chicken spring rolls for snacks. All of this would be done with a glass of wine, [...]

Bacon Cheddar Cornbread - [...] at 350•F until edges are brown and middle has set (about 30 minutes).I got very good results baking in our earth oven.Let it cool a few minutes before cutting. Moist, crumbly and fragrant. You can also try variations [...]

Beau - yall are yahsome

Derek - LIKE!

Larry McDowell - What a great family project! I’m glad I stumbled upon it.

Billy Kearney - I am curious about the rocket stove exhaust pipe. Did you also put a chimney there near the front door? I was planning an oven and stumbled on this brilliant blog. Thanks for the inspiration!

Mandy Sol - Excited to try this out at our school farm here in South Texas! Thanks so much for sharing, it looks lovely!

Tetrapak - This is Art ! BIG hello from Serbia !

Hunter Vaughan - Inspirational and impressive!…what a kiln.!!..such a beautiful thing to build together as a family… nuff respec on all of these posts and endeavours…this 1 is a particular fav! Just great!…

David Castillo - It definitely looks simple and fun to do, but what did you do to the chimney part? did you cut it out? I would like to try this as well. What can you do if your earth does not pass the shrinkage test?

milton - Here in Bolivia where this small scale dairyman (originally from Indiana) has lived for about 40 years, many village homes have clay or brick direct-fired ovens. They usually bake their bread in metal pans rather than on the floor of the oven. I had one such in the past but need to build a new one and am fascinated with the incorporation of the rocket stove principle into the design. The pictures are great but I would like a little more detail about heat transfer into the baking chamber. Is it all from the pipe leading up into the baking chamber and then exiting through the chimney at the front. Or is there significant transfer directly vertically up from the fire chamber tube through the floor of the oven baking chamber. Maybe by now there are some more plans, pictures or documentation of subsequent constructions— I’d sure like to see it if there is. I live within the Tucabaca-Serrania de Santiago forest reserve and the fuel wood economy would be a most welcome feature here.

Thanks for making this available,

Milton Whittaker

Darrel Smith - You have to be careful with galvanized metal. At higher temperatures the galvanization becomes a poisonous gas.

Build Your Own Earth Oven » FreestyleFarm | Wilderness and Survival - […] via Build Your Own Earth Oven » FreestyleFarm. […]

Maggie Fry - Great post! I have been putting this project off far too long. I love how the chickens sneak into so many of the photos.

Sherry E. - This is what I’ve been looking for. ..yea!

Karen smith - This is amazing.

John - Thanks for sharing, I have Denzer’s book, but besides a chimney, I wanted the fire under rather than on the baking floor. The Rocket stove approach is perfect.

caroline fawcett - loved the simplicity of oven making, wonderful photos, may attempt to make one in the future!!

Louis - Replace that galvanized with stainless or high carbon steel. Heating galvanized metal can vaporize the zinc, it is extremely bad for you.

betty - Thanks for instructions! I want to build one this. The kids are beautiful as is ur site right on the lake.

L R Roberts - Great article!!!!

Michael Valoppi - Beautiful and inspiring work… I will be building one of these this summer. Do you happen to have a picture that shows the stove pipes and the oven. I think I understand it, but I am not completely seeing it.

Blessings to you and the family…

Michael

janice slack - This is amazing we are going to build it!

Arathi - This is so so inspiring…. Longing to try it once the rains have settled.. Thanks so much for your detailed how-to with the pictures…!!! Your oven and the food looks absolutely amazing!

Douglas Sanchez - Hello.
I am Douglas Sanchez from Nicaragua. I would like to build an earth oven. I saw photos of your earth oven. It´s nice! Have you in pdf the book called: Build your own earth oven”?
Maybe you can share.
Thanks in advance.

Sam - Ahhh.. that remind me when I was young watching my dad and his friends building an oven just like that (minus the foundation)
He built the ovens using the Straw\Mod combination which normally last about 1 year… He would build it tall enough to fit two full lambs or goats. hmmm.. nothing beats the flavor and juicy meat cooked on these ovens.

Don - Hi – many thanks for this blog, and for such great documentation of a great project.
I’m about to build a cob oven and am now very excited about using rocket stove principles – but I’m not up to speed yet. Like several other commentors above, I’d rerally appreciate any sketches or plans or description to understand better. Mainly: what is going on inside? where does the chimney stop, what does the floor look like, etc.
Many thanks for any more detials
don

David (Happy House Farm) - WOW guys — so great to see the fun you guys had making your oven. We are in the Philippines and have visitors who LOVE pizza so it’s been a project on the line for a month or so now —

With your GREAT tips we can now use the jet stove design (which we use for our other stoves here) with the oven — so a perfect combo.

Thank you.

Power to Pizza!

gary - Beautiful job on your oven. I’m very interested in the Jet addition, although its not evident in the last series of photos.

Can you explain how you use it to heat the oven. I assume you start a fire in the horizontal portion of the tube and it drafts up into the vertical section which penetrates the inside of the oven ..?

I’ve read the jets use less wood, being more efficient, but how long does it take to heat. More importantly with your design you can start a fire again to maintain 700 for an all day pizza party ..?

Thanks

Gary

Abi - I love your rocket oven design! I hope to try one like this in the future. We made an ordinary (non-rocket) oven last summer. Here’s our blog post about it: http://www.theyrenotourgoats.com/homestead/making-our-cob-oven/

Do check it out if you’re interested in cob ovens! You’re right, there is nothing more satisfying than building something with your hands (and feet)!

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