How to Build an Earthen Oven

How to Build an Earthen Oven


In this video, we’re going to show you how
to build an earthen oven. The existence of ovens like this is easily
documented for the 18th century. In fact, just about every ancient culture had a very
similar oven. There’s one particular wood cut illustration from medieval times depicting
an earthen oven built on a wagon. There are references in 18th century literature and
also archaeological evidence that you would find ovens like this in private homes and
in fort settings. There are also references to communal ovens where the baker would bake
bread for an entire village. We’re going to need several things to make our mud oven out
of. We’re going to need sand. That’s the major component of our oven. We’re going to need
a good bit of clay. This is dried clay you can get at a masonry store or you can get
damp clay out of ditch bank. You’re going to need straw or dried grass or maybe hay.
You may need some bricks, so some fire bricks, even regular bricks will work, and you’re
going to need a canvas tarp to mix your cob together with and you’re definitely going
to need a good bit of water. Before you build your oven, you have to consider
what you’re going to build your oven on. There are historical examples of ovens built on
tables or on brick or stone plinths, on hearths. On the top of our very sturdy table, we’ve
laid out a layer of fire brick. That’s going to be the floor of our oven. We’ve also chalked
out here the design. About 22 inches across to the bottom on the inside. That’s the inside
measurement. The walls are going to be about 6 inches thick so we’ve got markings here
so we can see about how big it’s going to look on the surface. The door width right
here is about 12 inches across so we can get something as big as a pie in without too
much trouble. First thing we’re going to do is we’re going
to build the core. It’s going to be like a sand castle, just wet sand that we’re going
to build the oven over the top of. Sometimes you’ll see other people doing it with sticks
and things like this, but this is going to be much easier and quicker. This is where
our door is going to be. I just went ahead and put a couple of bricks in here to be the
inner core of the door. They’ll be removed. And right here I placed a brick wall to give
us a nice flat surface to build up against. So we’ve taken about an hour to put this together.
We’ve used very wet sand so that it stays into shape. Now we’ve got to make sure that
this stays wet until we get our first layer on. There aren’t very many critical things
about the shape and the size of your particular oven but there is one critical thing, and
that is the height of the opening tunnel here compared to the height of your dome. These
need to be a particular ratio or else the air won’t draw through this when you’re burning
the wood inside of the thing. So, this is between 65 and 60% or about 63% height here
compared to the height there. The next thing we’re going to do is put paper
on this. We’re going to put paper, we’re going to wet it down so that it’ll give us a layer
to separate so when we take the sand out it doesn’t stick to the inner surface. We’ve got the paper covering done on our sand
inner core. This will make it much easier to take the core out from underneath it. Now
it’s time to make the first layer of cob or mud to put on our oven. This inner most layer of mud or cob that we’re
going to put on our oven is just sand and clay. About 2 parts sand to 1 part clay. You
mix those two together so that they’re very well mixed and then we just put it on there.
We want to make sure it’s got about the right consistency that we can still work it but
it isn’t so wet that it’s sloppy, and you want to make sure to have err on the side
of a little more sand than too much clay. The more clay you’ve got the more it’s going
to shrink and crack. So you probably want to make up a bunch of
this cob beforehand. It ages well. It won’t go bad waiting overnight, and that way, as
soon as you’re done with your sand castle core, you can start putting it on right away
and you don’t have to worry about that drying out and blowing away while you’re making your
cob. So, learning just the right consistency can
be a trick. As you see here, I’ve been stomping on this pile for a little while and this is
starting to feel really good. It forms up into a ball, like a snowball. It doesn’t deform
easily. It’s not sloppy and you can still form it into any shape you want and it’s not
too drippy either. That’s what you’re looking for, something that holds together well but
still moldable. So we’re working on putting this first layer
on. This is a layer without any straw in it because that would just burn up anyway. It’s
about 3 inches thick and we’re starting at the very bottom and we’re going to work our
way up, that way we can watch as we go to make sure our thickness stays about the same. Well, we finished the inner mud layer yesterday
afternoon and we let this set overnight and it’s just slightly firmer than it was. We
don’t want to let it get too dry or else the next layer won’t adhere to this layer properly.
We’ve scratched this layer a little bit so that the next layer of cob we put on here
will adhere nicely. This next layer of cob that we put on, it’s going to have grass or
hay or straw in it to give it a lot more strength than this inner layer. We’re going to mix our clay and our sand first.
As soon as that’s getting close to the right consistency, that’s when we’ll add our other
binding material here. So, we’ve got this mixed up. I’m going to
mix this up just slightly wetter. It’s feeling like a pretty good consistency now under my
feet and since we’re going to add in this dry straw here, it’s going to dry it up a
bit so I’m going to start with slightly wetter mixture, but we wanted to get this mixed first
and then add in the binder. This will add some amazing strength to it.
When it dries up it really binds it together. So it’s helpful to make this cob up beforehand.
It really makes it work better if its couple days old, but you don’t want to let it get
too old because as it’s wet for a long time, the grass will start to rot in there, so you
don’t want that to happen. If it’s a day or two old, keep it wrapped in plastic so it’s
wet and pliable. It’ll really work even better after a day or two. So, to make this go faster, I suggest you
invite a bunch of friends over. Have a cob party. They can be stomping on this stuff
while you’re putting it on your stove. Everyone will have fun. Well, I’ve got about five or six big loaves
of cob here ready to go. I think that’s a good start. I’m not sure exactly how many
it’s going to take to cover this oven, so we’re going to put this on and then I’ll see
how much more I need to make. I’ve got marks here on the table to get about
2.5 to 3 inches for the outside layer. I’m going to start putting on our loaves. We’re
going to make sure they butt up well with the inner core here so there isn’t a big air
space between them, and I’ll just start adding these on all the way around. Okay, there it is. We’ve got the second layer
of a cob type material on here. This is the stuff with the straw that’s built into it.
It does, as you work it, it kind of sags down some so you might want to start a little thinner
at the bottom than the finish, expecting some of it to sag down into position a little bit. This gives us a good opportunity to look at
the cross section of what’s going on here. You can see the cobs a little thicker down
at the bottom than it is at the top because it’s kind of sagged a little bit. You can
see our outer cob core, our inner core that doesn’t have the straw in it and here’s the
sand core on the inside. We’re going to add a little bit to the outside here. We’re going
to give it a nice rounded opening because a rounded opening is going to have more strength
than this sharp edge. Well, we’ve finished putting our rounded opening
on the oven so it will be a little bit stronger. We made sure to make the cob that we added
back into this outer stuff. Whenever you add two pieces together you really have to work
it so that the two pieces adhere to each other and it just doesn’t fall off. We added a little
bit of sand on the front to help support that lip. Depending on where you’re at, your environment,
the time of year, what the humidity is, this will take 2 weeks, 3 weeks, 4 weeks, maybe
even a little bit longer for it to get dry enough for you start to even think about warming
it up from the inside. While this is drying, you don’t want it to
get rained on so you’re going to protect this from the weather but don’t cover it with plastic
so that it can’t dry. So you want to protect it from the rain but let it breath So, it’s only been about 24 hours since we’ve
been here last, but it’s firmed up enough with how the weather is here that we were
able to go ahead and pull out some of the sand. I haven’t gone and dug the whole thing
out but I want to let it start to dry out on the inside and even peel off some of the
paper if you want to. That will all burn out anyway, but we just dug it out about halfway.
We’ll come back in a couple of days and take out more. We’ve removed the sand core from this oven
and we’ve given it a couple weeks to dry so it’s almost ready to fire. You may not have
to wait this long if you build an oven but if it’s not adequately dry before you fire
it, it will cause cracking or at least more cracking than normal in the body. Even if
you wait like we did, it’s inevitable that some cracking will occur. Don’t be alarmed.
If the cracks are especially big, you can repair them with a little extra sand and clay
and let that dry in place. We’ve employed a few warming fires in this
oven and it’s dried out well. We’ve gotten a few cracks but overall we’re really pleased.
The walls of this oven are extremely durable. Here’s a brick of the material and it takes
a lot to break this material up, so if you need to do modifications, you’ll really have
to chop at it. However, as sturdy as this is, it still needs to be protected from the
weather. This is water soluble and it will just wash away with the rain, so if we need
this to last a while we’re going to have to build a little roof over it. Make sure to watch part 2 of this video where
we learn how to bake bread in one of these earthen ovens. You know, this looks pretty
good. I think I’m going to fire it up.

100 thoughts on “How to Build an Earthen Oven

  1. receipt for building small inground home too. get the receipt just right and makes nice little cottages like in Iceland. Also the Spanish use this receipt lot to build a whole house.

  2. I built mine on a steel table. Everything else is much the same, but mine has decomposed granite in the mix, and the flue is at the door end. It is absolutely brilliant. Nothing roasts meat as well as one of these.

  3. even for the represented time, this oven is maximum primitive. even 400 years ago ppl knew that smoke is hot and fire needs fresh air and so, if they built a proper oven, they built a chimney that comes from the rear of the oven-top over the oven-top to the front and then back over itself. they would also add a proper fresh air supply.

  4. Seen people apply a Lime finish to weather proof buildings made of COB. Could this technique be used for the oven?
    Love your videos, thank you for the wonderful info and inspiration!

  5. Seen people apply a Lime finish to weather proof buildings made of COB. Could this technique be used for the oven?

  6. Wow, while I am so fascinated having the modernized version, i would always love coming back to the most natural, traditional way to cook my yummy burger buns! Thanks for this video, it greatly helps!

  7. I LOVE your show! My grandparents lived kinda like this. Your show makes me feel warm inside because I remember those simple but savory meals from upstate NY. Bless you and your show

  8. I've also heard of people using dried cow poo instead of straw to make their cob I'm assuming probably not for a cooking oven though lol

  9. I bet that clay feels good on your feet. Probably good for the skin, too. What happens if you add limestone or ash to the clay/sand mix?

  10. I am so not looking for the clean up because my girls will have a lot of fun helping me with this. …. but my golly miss molly I so need to make one of those, I have the raw materials on my property. As always you gave me a great way to cut bills. Do stuff yourself and you save money 👍

  11. Almost exactly how my grandparents built one at one of their hunting camps when I was a boy. It’s been more than 44 years and we still use it at family gatherings or whenever one of my vast family uses the place.

  12. This guy is either having a midlife crisis, failed in school and this is his job, or his wife died/refuses to fornicate with him.

  13. What kind of sand should I be using for this? I have access to all the beach sand I need but I'm worried about the salt content? Thoughts?

  14. I know this is an old post but gonna ask anyways. Would you be able to add manure to straw mixture as in wattle n daub to help prevent cracking?

  15. This is one of my favorite videos on YouTube. I just love seeing the methods employed, the progression of the build, and the beautiful end result. I love the little door too. I can't wait to make one of these myself some day.

  16. 3m seels micro spheres to mix in such heat insulation   if you use such you can melt glass in one of those oven    or may be go for an easier structure

  17. Great video Jon! Many years ago, I had the chance to make Adobe bricks and the mud covering used at Sonoma Barracks, California, circa 1810. The bricks were made using sand, clay, and water. Once laid in place, they were covered in a matrix similar to the oven matrix shown but instead of hay, the Spanish employed horse hair. In my fieldwork, I encountered dozens of outdoor ovens dating from the Gold Rush era, 1849 to 1862. The ovens, typically associated with southern European occupation in California, consisted of a clay interior roughly 6 to 8 inches thick. To protect the over from weather, this was covered with either a motared layer of cut or uncut fieldstone, or, if available, commercial fire brick. After 150 years of exposure to the elements, these "Behive-shaped" ovens were sometimes completely intact. Other times, they had collapsed and could be observed by nondescript piles of fieldstone. That when pulled apart often revealed melted clay matrix.

  18. Nicely explained film thanks. I live in the south of England in a cob cottage that was built onto a rubble stone plinth with a thatched roof of straw built over wooden beams and rendered and plastered in lime mortar.
    I found that when repairing another cob building we used 2 wheel-barrows of the clay subsoil to 1 wheel-barrow of sharp sand to about 1/4 of a small bale of straw which was chopped into smaller pieces uses garden shears. The straw helps to stop the cob from shrinking and cracking and I'm guessing that the big cracks that you had in your oven were probably because you used too much sand.
    The clay subsoil that we used was so solid that we had to use a metal bolster to help cut it from the ground whereas your clay was powdered and had to be brought in. The last time I saw clay like that was when I opened up a 50 year old, oil fired Agathermic oven which I had to dismantle to remove it from my kitchen and it was filled with the powdered dry clay which helped to insulate it.
    To mix up the amounts that we needed for the outside and the 1 foot thick internal walls we used a JCB digger but for any of the smaller amounts needed we mixed it on top of multi-ply board which made it easier to shovel from the outside of the pile to the centre, slowly adding water as we walked in it using our booted feet rather than barefoot.
    It was all left to dry out for about 3 weeks before I plastered on a 1st scratch coat of the haired lime mortar then another week before the 2nd coat and the final top coat of lime skim was added when the 2nd coat was dry-ish.
    This former farmhouse was built on the edge of a forest on Dartmoor in Devon and the basic structure was medieval it even had 2 beehives in one of the outer cob walls and an end room that was built entirely from stone about 4 feet square and about 10 feet high that was used for a slow fire which the ancients used to smoke their meats and cheeses, like an early fridge.
    In the passageway walls under the gypsum walls that were plastered in the 1960's we found beautiful wooden panels with about 6 'Daisy wheels' carved into the surface. The Daisy wheels were designed to ward off evil spirits and during the 1960's two of the Great Train Robbers hid out in this remote place. The Great Train robbery was Britain's first big robbery where the thieves held up a Royal Mail train and stole about £2.5 million.
    You can see all that I have been talking about on the small 6 minute film I made at the location in 2012, click on the link and leave a comment please.
    https://youtu.be/yZ56XlXXt-Y

  19. "I can't wait to build one of these in my apartment." gets 692 likes. Grizle's and Gozer's well informative comments right down bellow gets 162 and 60 likes. what the hell is wrong with people?

  20. Awesomely old school as always <3
    In southern Greece were I hail from we used to build earthen ovens on a plinth of stones laid dry (the top would be soapstone, even better than firebrick if you can find it, and/or dark colored stones which must have been basalt although I cannot really confirm this), reinforced with a lattice like frame of simple river cane or reeds around the plinth. The frame which held the adobe and cob in place, was an old coiled basket made of straw or river cane, one no longer serviceable, which would burn clean leaving just some imprint of its sides and bottom therein. The dimensions of the basket were quite similar to the one you've built in the video.
    This method ensured that the structure was dry enough to test fire in less than a week if the temperature is over 20 degrees Celsius (it was late April, the time were these ovens where usually built in the surprisingly wet climate of mountainous western Greece). The caveat of the method was that when the core was ready and scored, the second layer was laid and covered with bark shingles squeezed on the surface of the cob. The bark was sourced from a European pine tree, but that was just a random pick that was available. This was covered with a tarp until it was ready to be fired and then left on the open air. Gradually, the bark shingles would disintegrate and be used as feed stock for the fire in the oven. They can be replaced with ceramic tiles laid with common lime, sand and pozzolana mortar.
    I took part in building such a structure when I was 12 years old and it is still serviceable after 24 years 🙂

  21. I want one some day! Ate a great pizza in a cob oven at the Cob Cottage Company years ago. Knowing how to create one is one of my emergency preparedness projects, I keep all the materials on hand.

  22. This is a basic first oven used in every human culture since time immemorial and still used in little lovely places that cook traditional breads. Cheers for a beautiful job and video!

  23. When I was little I made a “birds nest” out of clay and dried mud. After it was dried I tried to throw it up in a tree. It went in the tree and shortly after fell out and put a massive dent in my dads truck topper. 😭 I can attest to how tough this oven will be.

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