Building a woodfired oven with clay or mud
After having built a oven for myself, i think it's a nice to have piece of work in your backyard.
Be warned, it takes quite some time to build, but also to use it. It's no substitute for your Microwave... it's rather in the slowfood class, even if you can bake a pizza in 2-3 minutes.

Step 1: What Type and Size Do You Want?

Depending on what you want to bake and the space available, you can adjust the size of your oven. The amount of material needed doesn't scale linear. My oven needed 4 times the material of a small but usable oven.
In numbers that was 600 kg of clay powder, around 950kg of sand.
In my case, the size was selected because my main use of it is to bake bread and i wanted to be able to use the cookie pans from my electric oven. I also selected the thickness of my thermal layer to keep the heat long enough to bake multiple batches of bread, without the need to reheat.
As a general guideline, i wouldn't go smaller than 40cm/16inches inner diameter. Mine has 75cm/30inches. The thickness of the thermal layer should be no less than 15cm/6inches. Mine has 20cm/8inches.
At some point you need to decide whether you want a chimney or not. I had the chance to use a oven with a chimney, but decided against it for my oven. The main advantage of a chimney is to take the smoke out of your face. The main disadvantage in a simple design, lots of heat will go out the chimney instead of heating up your oven. It also adds complexity to your design. If you need to add a chimney, because your fire doesn't burn cleanly, you can do it even after finishing your oven.
There are certain ratios between inner oven diameter, inner oven height and oven door height you need to have. The most important here, the oven opening height has to be 63% of the inner dome height. This is essential for a clean burning fire. Further, the inner dome height should be 60-75% of the inner dome diameter. With these ratios and measurements, you can determine the actual measurements for your oven. It's best if you look around for firebricks, before you decide on the size of your oven floor. You should sketch your firebrick layout on a large piece of cardboard 1:1. Then draw the inner and outer shape of your oven on it and cut it out. This will help you in the next step, the form and size of your foundation. You should place the opening of your oven away from the main wind direction. Last but not least you have to plan for a roof of some sort. If you plan to bake in bad weather, make it big enough to shelter you as well as the oven. The oven should be able to breathe, so the moisture can get out.

I would like to strongly suggest for everyone to read the book from Kiko Denzer, "Build your own earth oven". It goes much deeper into the details, he built countless different ovens and shares his knowledge. You will see references to his book throughout this instructable. Don't get me wrong here, you can build a oven with this instructable alone, but maybe you'd like to do it a little different. In this book, you will find different techniques, styles and lots of background information.

Pictures of smaller ovens made at a workshop. One with chimney, made in the sand mound method, the other without chimney was made with the inverted basket method.
<p>Hi, </p><p>Great Instructable! I am thinking about building a pizza oven of my own and wondered how to keep the oven hot. Do you light the fire then take it out? Do you leave it in there and bake around it?</p>
<p>Hi, </p><p>thanks for you positive comment</p><p>It depends, what i bake. When making pizza, i keep a fire going at the side. I also keep the door open. This way, i can bake pizza for several hours at a more or less constant heat. It needs some experience and a contactless thermometer helps a lot.</p><p>When i bake bread, i take the fire out. Anyway, it's a good idea to bake bread with &quot;falling&quot; heat. (starting high and let it cool down with the door closed)</p>
<p>Nice article mate. I'm creating an series of articles on pizza ovens. Feel free to have a look and perhaps try a slightly different design (eg. Barrel vault or Neapolitan dome) for your next oven. </p><p>http://pinkbird.org/w/How_to_build_a_pizza_oven</p>
<p>Hi Eli</p><p>A lot of text, you wrote... nice!</p><p>Before i built my oven, i also did some research on different designs. I originally built it for baking bread. When i attended a cob building workshop, i asked if i can bring some dough to bake. I fired up a (dry) oven made in a earlier workshop and the bread came out fantastic. Later i found out, that the bread came out so good, because of the prolonged fermentation... and not (only) the oven.</p><p>I don't think, i will build another oven. At least not for me... I'm quite happy with mine. I built one at the workshop, then mine and then one for a friend. I also bought a used professional electric pizza oven two years ago.</p><p>A friend in Germany built a barrel oven with firebricks. He told me about his build, it took him quite some time and stash.</p><p>Now i'm enhancing the doughs and toppings ;-)</p>
Definitely a good plan. I agree once you've got your oven working you must spend time perfecting the actual pizza! :) You never know, you may move in the future and will want to build a new oven at your new place. <br><br>Regards, Eli
<p>&quot;Here pictures of my latest build. Smaller and faster to build. <br>Instructable will follow.&quot;</p><p>Where is the newest instructable? BTW. I am making WFO in a few months and this is the template I will be using. Thank you.</p>
<p>I will see, what i can do...</p><p>Anyway, this will be only a foto report of the build with cross references to this instuctable. I don't find the time to rewrite it completely. (So many projects, so little time ;-)</p>
This is awesome! I just built a pizza oven in my back yard. It's not as easy at it looks, believe me, but well worth the effort! I got my hands on this detailed step by step guide, helped out a lot, check it out <a href="http://www.buildapizzaoven.org" rel="nofollow">www.buildapizzaoven.org</a> <br>
Awesome oven. Thanks for the tips. We made one with clay dug from our lake. It makes tasty pizzas, stuffed mushrooms and bell peppers..and actually it makes everything taste better.
Very nice <br> <br>Here pictures of my latest build. Smaller and faster to build. <br>Instructable will follow. <br>
Nice! that is very sleek and compact. We put a vent at the top of ours, but I'm not sure if that really helps or hurts the design.
If you want a vent, you should place it close to the front. <br>We built one with vent at a workshop. <br>But you loose heat in such small outdoor ovens. <br>I don't care, if it smokes out of the front opening. <br> <br>
cool. nice smoke stack. is that a clay ball at the top?
Exactly, but it didn't tightly fit. So we still lost some heat. <br>When i did that again, i would wait until the smoke stack is somewhat hard. <br>Then place a plastic film on it and press the ball in place, so i get a tight fit. <br> <br>We also had some kindergarten teachers in our group. They wanted this design ;-)
Ah, nice idea.
Hi clay Pizza oven lovers. aside from my blog (http://clayoven.wordpress.com) I have now produced a downloadable eBook containing everything you need to know in order to build your own oven. Have a look and tell me what you think:<br><br>www.clayovenbook.co.uk<br><br>Happy building!<br><br>Simon<br><br>:-)
Hey Simon,<br>does your eBook sell?<br><br>Check out this site, if you haven't already.<br>http://www.varasanos.com/PizzaRecipe.htm<br><br>It's a long read... i PDFed it and put it on my Android phone to read offline.<br>I made a dough for a &quot;Flammkuchen&quot; with his method (hydration and wet kneading) and it's amazing. I made it with yeast only, i'm still waiting for the delivery of my sourdough cultures.<br>I kept it in the fridge for 3 days. <br>I made it in my 300&deg;C electric oven on the pizza stone.<br><br>Try it, you won't regret it.
Wow that guy clearly has a pizza obsession! Amazing.<br><br>S
Yeah, he went all the way.<br><br>The section about different flours and kneading techniques is very enlightening.<br><br>It's the most secret-revealing text, i've ever seen. <br>And best of all, he speaks from his own experience.<br><br><br>By the way, i'm going to build a oven for a friend this spring. It will be a bit smaller and without a door.<br><br>The foundation is already built and my big bakers kneading machine for kneading the building material is already on his property.<br><br>Maybe i take some photos of the building process. My brewing buddy, who helped on my oven will also help. So i guess we can finish it in two days.<br>
I'm VERY intrigued by this &quot; big bakers kneading machine&quot;!<br><br>S
Doesn't seem nice to advertise your book on the back of someone else's intructable.
All of the instructions to build the oven are also still freely available on my blog but I know some people like a good old book. Also, my oven is different to the one featured here. <br><br>Simon
Technically you are right, but it's ok with me. <br>Look at it as further reading.
Too complex. <br><br>Simple brick oven = faster.<br><br>or temporary mud/clay/earthen oven. Just enough for a year or two's worth.
I wouldn't say that.<br><br>I'm enjoying it the fourth year now.<br>As long as the roof stays up, this oven will survive me...
I agree. Mine is almost 4 years old now and although it has had quite a battering (I have neglected it a little to be honest) it still works great. Have a look at my latest post and video showing the winter damage:<br><br>http://clayoven.wordpress.com/2012/03/12/winter-damage-again/<br><br>I fired the oven up immediately afterwards and she worked just like the first day she was built.<br><br>S
Now i need to learn how to make pizza!!!! HAHA
Try this text, it's very long and very thorough.<br><br>http://varasanos.com/PizzaRecipe.htm
hey could i use handmade bricks or ed bricks for this
I don't see, why not. <br>As long, as the ovenfloor is insulated from the foundation, you can take about everything. We used a wooden structure for the temporary ovens in the workshop.
oh okay i just love handmade bricks and was wondering hey have you thought of useing a eltric heater as well as fire for heat
I have thought about electric heating, but to in order to heat up such a monster(in terms of thermal mass), you'd need quite a couple of kilowatts. What your standard wall plug delivers, woult take very long to heat it up.<br>I was also thinking about propane or natural gas heating. Here you can crank out 10+ kW at a reasonable price.<br><br>But then, why do i build a wood fired oven in the first place? Because i love (controlled) open fire.<br>It has a Zen-like quality to fire up the oven, while the dough is rising.<br><br>When it's dark, after making many pizzas in the afternoon, i take a chair, throw some crackling pinewood into the oven and watch the flames.<br>That's better than most TV-programs, especially with a homebrewed beer or a red wine at hand...
yeah i just meant as a added benfit
Thomas, that was a FANTASTIC Instructable! Great job and your English is just fine. Thanks for sharing!
i was wondering what is the color of the clay? because in my country we seem to have high rich clay content in our soil. and also would the oven survive heavy rain because 6 months is of the year is the rainy season and we don't have snow so frost is not a problem. and when i dug in my yard i found a hard dark soil under the gravel
Well, clay comes in different colours. My building clay was brown when wet and beige when dry. <br>For the final touch-up layer, i used a red one.<br>But i have seen from light to dark grey and even blueish clay.<br><br>If you let a ball of your dug dark soil dry, it should get stone hard. It will also be somewhat brittle and have some cracks due to drying shrinkage.<br><br>If you don't want your oven to be gradually washed away, you need to protect it from rain. (A roof also helps to keep the pizzaiolo dry ;-)<br>The clay is not fired on the outside, so it stays water soluble.<br>
thanks ill try that and when i dug in my yard i had to use a pickaxe to get to the dirt because it was so hard that i couldn't use a spade, so maybe its a good sign? and by the way it had rained only a week ago and the dirt is very hard now.
i just made a small ball last night and how its rally hard like a stone and when a dropped it from shoulder height it cracked and broke like a brittle rock and like you said it formed some cracks due to shrinkage. i think that this would be a great material if i let it mix with sand
I have some old concrete 'urbanite' - it has a really high aggregate content - do you think that would work?
I didn't have to do it, so you have to judge for yourself. If you have it around, use it.<br>I would pick up stones from a nearby creek, because i don't have &quot;urbanite&quot; around.
Thanks - I'll give it a shot - great instructable.
hi - I was wondering, the River Cottage Bread book has some instructions on this - and they suggest doing three layers - innner, 'insulating' (with woodchip mixed in the clay' and outer. Any point in doing this?
I don't know this book, but it certainly makes sense. I did it somewhat similar. The inner layer is also called the thermal layer. It's made of clay, sand and shredded straw. The thickness has to be 4-8 inches. This gives the thermal mass of the oven. (mine is close to 8 inches) This means the oven keeps the heat longer, but also needs more time and fuel to heat up.<br>I did some test bakes with only this layer, but i planned a insulating layer from the beginning.(you can see the oven without insulation in step 6 picture 3)<br><br>The oven got quite hot on the outside, so i made a insulation with a perlite clay mix.(perlite is a foamed mineral like pumice)<br>The outside temperature fell by half, keeping the heat even longer.<br>With woodchips, i guess the insulation needs to be a bit thicker than mine.<br><br>The third layer is for protection and good looks only. I did it with a red clay and fine sand.
I myself will be building two of these this summer. After a lot of reading it appears that your door ratio may be a little on the large size which would result in a large heat loss. Would you agree with this?
Hello<br><br>as described in step 1, the calculation only covers the heights of the door and the inner height of the dome. The width of the door can be smaller of course. I just used, what was available at that time. (i wanted a minimal width to use the trays from my electric oven) The opening also doesn't have to be rectangular.(In most ovens i've seen, it isn't.
Hi t.rohner!<br><br>You can also build this oven making a mold with fine and wet sand as you want inside. Cover with clay, as you did. When dry, open the door and take the sand out for next building. You may use soil cement in a ratio of 18:1 with bamboo slivers either to build the oven or to cover it. Ok, it's a little bit more expensive.<br><br>How much water to use with soil cement? Get in hand some clay and squeeze. Falling just a drop of water is perfect. <br><br>To avoid cracks mix sugar with clay. Warning: the mass is slightly softer with sugar. Wait to dry completely and fire strongly. Using cement, don't forget to wet for 3 weeks, to keep cement cold and just use after 30 days. You can use sugar with cement too. Very good! <br><br>Then, good pizzas, good breads and much more!
Dude you AWESOME !!
amazing... thankyou, you've inspired me.... I'm going to start collecting materials and plan for my own oven. Have wanted to make one for about a year but have never been brave enough on my own even with lots of research!! This is a very helpful concise and enjoyable instructable to read...will try to enlist the help of my friends with the promise of pizza and home made champagne!! :-)
Thank you for your nice comment. Some help is definitely desirable. What kind of champagne do you make? I used to make elder flower &quot;champagne&quot; for years. This year i made elder flower sirup. It's very nice in a glass of prosecco or champagne.(even with plain water...)
I'm curious why you didn't use quicklime, the fireproofing and waterproofing ingredient i've read about in cob books. I've made mud bricks in Mississippi climate, they just melt away in the rain, without quicklime added. I submerged a quicklime brick in water for over a year and it remained hard. <br /> I'm guessing the temperature of the oven turns the clay into ceramic? But I wonder if the straw burns without the lime to protect it?

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