Make pizza with a plasma cutter, a backhoe and a pile of mud!

After several years of baking in North House Folk School's wood-fired brick oven, I decided to build an oven of my own. I went a little crazy with extra features (slab foundation, arches, ash dump, chimney, doors, wood storage) and decorations (limestone around the foundation), but you can make a very usable version in a weekend with salvaged materials and a couple of friends.

The place to start is Kiko Denzer's "Build Your Own Earth Oven".

I also made extensive use of Daniel Wing and Alan Scott's "The Bread Builders", which is a great resource even if you're baking bread in a regular electric oven.

Step 1 Bushwhacking, Lumberjacking and Limestoning

We have a big lawn next to the neighboring farmer's field, with a great view of Carleton College's wind turbine. What a great place for a pizza party!

The most obvious place to put the oven was in line with our garden shed, but the whole area was a dense jungle. I spent a day with our Stihl brushcutter, with a saw blade in place of the string trimmer. That thing would be awesome for fighting zombies!

I had to chainsaw out a medium-sized box elder tree as well.

Under all that jungle, I discovered an improbable trove of cut limestone left over from when they built our house in 1973. Too good! I'll use that for the keystone and the stone veneer around the foundation.

Comments

[beckenham]

Hello Fritz, Wonderful instructions. About the foundation - did you go below the frost layer, or is that simply a pad? Thanks.

[beckenham]

Sorry - I see that you poured a slab. Have you been through a winter yet? I'm wondering how it's holding up.

[fritz.bogott]

It's just a pad, on about a foot of gravel. Definitely not best-practice. We figured that the consequences of a big ol' crack through the concrete pad just weren't severe enough to justify the effort of a properly-built foundation. If the base were mortared or if the oven were brick we would have made a different calculation. But we've been through two Minnesota winters with it and it looks like new.

[PaddyKevin]

I am wondering if concrete pavers instead of a slab over the bed of gravel that you descibed would be the easiest way to go and not have to worry about cracks

[antonio.carrillo.bolea]

Made my own earth oven!!! After several re-readings of your proyect, I finally made it! I work in a proyect located in southern Veracruz, México, and we are fortunate enough to have clay everywhere... (www.losamigos.com.mx).

I want to post the memories about the construction I wrote on our blog.

http://estampaverde.blogspot.com/2010/04/fiat-panis-o-de-como-hacer-un-horno-de.html

Its in spanish, but anyways... I might try the wood door because there isn't any metal workers around!!! Any advice on baking??? How long shall I leave the oven to dry before starting a big fire???

[fritz.bogott]

Hi Antonio,

(Pardon my English.  I speak German and Chinese but very little Spanish, even though I could use Spanish every day in my own town if I had more time to put toward it...)

That oven is beautiful!

I don't know how long to let it try.  Mine is cracked on the inside but is still holding together.  I don't know whether it would have cracked less if I had let it try more???

Certainly the first couple of firings will eat a LOT of fuel as the fire burns out the remaining moisture.  You'll want to start three or four hours before you cook.  Once the dome dries out it will take more like 90 minutes.

When you first start the fire, the oven ceiling will turn black from smoke.  It will stay black until the dome surface temperature hits around 530DegC.  Then the smoke will burn off and you will see clean clay.  In my oven (which I built too thick, I think) I keep firing for about 30 minutes after the clay burns clean.

When I bake pizza, I leave all the coals in the oven and just push them to one side.  You may need to keep feeding skinny sticks onto the coals so you get some radiant heat from the flames to brown the top of the pizzas.

If I'm baking other things, I shovel the coals out, mop the floor, and then use the 'ouch' test to test temperature.

At pizza temperature (375-475DegC), I can't put my hand into the oven at all.

At bread-baking/meat and fish roasting temperature, I can count to three until I have to jerk my hand out.

Much longer than three and the oven is colder than I use for much of anything except beans and stews.

Ask me more questions any time. I love to talk about baking!

-Fritz

[materials]

fritz-what would you say to topping off my adobe bread/pizza oven with clay brick and a mortar mix w/perilite? the oven works nicely as is but to make it more wisconsin weather-proof- i don't want to make a shelter for it because of where it is located nor keep a tarp over it except for winter weather-i've been thinking about it and i can't see any reason that it would disturb the tempertures-i would really like your opinion on this thought-bev

[fritz.bogott]

Hmm.  You don't want to wrap adobe in anything waterproof without an air gap, because then the steam inside the oven will condense on the waterproof layer and turn the adobe back into mud.  That's what's going on with those A-frame roofs-- oven, then space for air to flow around the oven, then a waterproof roof.  As long as there's an air gap, you're fine.  I don't know whether that automatically breaks your "no shelter" requirement?

[abadfart]

very nice i might make one for my self

[PaddyKevin]

Greetings.  I have questions if you do not mind.  First, if, like me, metal work is not going to be practical, what would you suggest the doors be made out of?

Second, I was wondering if you thought of using the bottom area as a bbq smoker, with a tad of alteration I suppose

Kevin
Buffalo, NY

[fritz.bogott]

Hi Kevin,

The Denzer book (which you should buy because it's great) suggests making a door out of adobe or wood.  You may need to soak a wooden door in water for a few hours before using it so it doesn't scorch too badly and so it contributes some steam.  Anything would work though, really.  A stone or concrete paver if it's not too heavy?

As far as metalwork goes: I usually find that the most fun part of any project is hunting around my county for people who know the trades I'm missing and hiring/befriending them.  You meet new people and learn a lot, and it expands your sense of what you and your growing crew can build next time.

You can totally use the oven as a barbecue pit.  Just keep a slow fire going off to one side and throw some soaked chips on the fire from time to time.

It's fashionable among molecular gastronomes and Make Magazine readers to use a computer-controlled blower to keep the pit's internal temperature as stable as possible.  <a href="http://www.mikezed.com/">Mikezed</a>, whom I met at Maker Faire SF 2008, encouraged me to try that with a cob oven.  I haven't gotten around to it, but perhaps you could pave the way?

-Fritz

[PaddyKevin]

Thanks so much.  That temperature controlled blower sounds good, but I like things as simple as possible.  Living in a similar climate as you, I am concerned with having to cover the oven with a tarp, but I suppose a protective wood structure around it after it is built might be neat, especially as you say if it is designed to allow moisture to leave

[fritz.bogott]

The canonical thing to do is to build an A-frame roof fairly tight over the oven, like this:

(Image CC-BY-NC-ND by kathryn_goddard1)

[materials]

time to mix up some more clay and perlite! fritz thanks so much for your help

[materials]

fritz: my mudd was cracked so badly i ended up taking it apart and starting over with new mudd yesterday-well i have it covered with plastic and it's doing some cracking close to 24 hrs later-question for you: how long after you did the mudd balling did you start the second layer of insulation? p.s. send good clay!!!!

[fritz.bogott]

The thermal-mass layer was sloppy wet when I laid it up. Mud ball: SPLAT! Mud ball: SPLAT! Wetter than dough, not as wet as batter. Oatmeal-wet. Wetter than you'd use for clay you were throwing on a wheel. I put the insulation layer on when the thermal-mass layer had the texture of silly putty. No idea whether any of this matters, or whether I did it "correctly," but that's what I did.

[materials]

fritz: i ran out of mud on the thermal mass (step six)-i'd say i got about 21/2 to 3 in. around sand dome-my question: now that i've got more clay is it possible to add it on to what is there or do i undo all of it down to the sand mound and start over again? one more thing i wanted to add is that i'm seeing cracking through-out it and i was very precise about adding 2 parts sand or more to the 1 part clay-is this also a problem on how my oven will function? help!!!!!!!!!

[fritz.bogott]

2 1/2 - 3 inches should be just fine. I'm actually a little sorry I put 4 inches of thermal mass on mine. A thinner dome is better for pizza (you don't have to pre-heat it nearly as long and it works just as well.) You'd want the whole 4 inches if you were baking multiple batches of loaf-bread for a big family, or if you were baking for market, or if you were serious about catching the entire heat cascade (flatbreads, then loaf breads, then roasts, then cakes, then beans or caramelized pan breads (pumpernickel, rye-n-injun) then wood for next time (Cooking with Fire by Maurice Sabbagh Yotnegparian (great name!) appears to describe some good cook-for-the-cascade ideas.)

For pizza and casual loaf-bread baking 2 1/2-3 inches should be just lovely.

My dome has lots of cracks and it holds more heat than I can use. (I used mud straight out of Chris's yard and didn't measure or test a thing except to observe that the mud was sticky.) If you were using the dome as a cooking surface (tandoor) you would care, or if you needed maximum heat storage that was very reliable (like for subsistence or commercial use) you would care. Otherwise you don't care.

If you are a perfectionist (which I'm not but which I can respect) then you should probably hit up The Fresh Loaf or try to bounce an e-mail off Kiko (I don't have good contact info for him but you could try phoning North House and leaving a message for him. (He's teaching up there right now.))

Where are you located? Maybe we should organize a couple of bake days.

[materials]

(removed by author or community request)

[fritz.bogott]

The pleasure is all mine. I'm baking white pizza with mussels and duck-and-olive pizza tonight. I'll stick the recipes up in just a sec.

[beckenham]

Fritz, Thanks for the feedback. If it can survive MN then I guess it can cope with IA! I appreciate the advice.

[Rouxyou]

I have been wanting an oven in my yard for the last two years much was total material cost?. LIving in Florida, there is an issue with clay and mud.

[koyaniskatzy]

I'm in Florida too and been recently working out in the yard. I started digging to install a pond and about 3 ft down the way the soil turned red. Would that be the clay layer? It doesn't crumble easily, and the clumps look like actual rocks. Rouxyou: Have you found more info? I'm planning on building an outdoor grill and an oven would be great since I would also like to learn how to make my own bread. Great Instructable!!!

[Rouxyou]

I bought the book Build your own Earth Oven by kiko denzer. Thats as far as I got.

[fritz.bogott]

Preheating a pizza stone (for pizza or flatbread) or a cloche or a dutch oven (for bread) in a gas grill turned all the way up works great too. Same principle as a brick or earth oven, and very similar results.

[fritz.bogott]

The Denzer book has a whole section on testing your soil. Great book!

[koyaniskatzy]

thanks, would it be too much too ask for the name of the book? My library catalog didn't pick any Denzer, and I may have to request it on swaptree. thanks again!

[fritz.bogott]

It's on the first step of the instructable, with a link to a bunch of places that stock it.

[fritz.bogott]

If you build one like in the Denzer book, you'll probably come in between $100 and $200. If you add a bunch of extras like I did, you'll end up closer to $500 - $600. But get the Denzer book. It's great!

[materials]

recieved my "build your own brick oven" and i have been reading it - i'm calmer now that i have it-but have to add excited to experience it in the making-have my foundation hole almost finished to add the gravel-thanks to you too -i'm going to do pictures of the steps to give to my grandchildren and perhaps build a little one with the almost 6 yr old if he would like-i've enjoyed ever so much your direction and replies and want to ask if the roof you had talked about making for yours in the works yet? bev

[fritz.bogott]

No roof yet. That's likely to be a project for next summer.

[materials]

fritz those doors are beautiful!!!! hats off to the artist-bev

[materials]

you are brave with that minnesota weather to do that and know about the float-i have reasons for not pouring a ground foundation and opting for the 4ft dig-all i can say is thank you so much for your prompt and helpful replies-i am so excited to get the digging going but alot of rain and chilly yet-good day here and there=just have to be patient-you've been great!

[materials]

hi fritz: thanks for answering back-you are so right about the confidence to build this-i want it to last for awhile and i do look forward to reading the book-cart before the horse in plans-digging 4ft down is the biggest chore soon for the frost line then doing a 4corner cement cinder block base........getting back to the question of "insulate w/paper-i'm calling it your step 10-and NO i wouldn't want that to happen to my bread making-all that work and to have that happen-back to the base-you didn't do that and i know what kind of weather winter can be for you too-i know the oven is heavy but i'm concerned about the heave and cracking the clay-were you concerned for yours?

[fritz.bogott]

Foundations are my least-favorite part. We eventually decided that six-to-eight inches of gravel under the concrete was the most we were willing to mess with. We just didn't have the spunk to dig down to maximum frost depth. We didn't feel too bad about the compromise, because our slab (which we reinforced with rebar and heavy steel mesh) is small enough to stand a chance of floating as a single unit rather than levering apart. You wouldn't want to take the same risk with a garage-sized slab.

[materials]

fritz: i was thinking of using high fired clay that i can buy from a pottery shop here-with your expertise knowledge can i do that?instead of the dig & find and add? for my lst layer over the sand mold then insulate with paper and again use more for the outer insulating layer and place some brick , tile or metal design pieces.......will this have to have a roof for mid wisconsin weather-alot of question i know -have to wait for order on denzer book and want to get materials purchased-thank you bev

[fritz.bogott]

I completely love the Denzer book and Kiko's general outlook on life. You should buy it in any case as an anti-negativity touchstone of how awesome people can be sometimes. (Plus it will help give you the information and confidence you'll need to build your oven.) Purchased potter's clay will work fine (it's the same stuff after all) but you'll need a LOT. I don't understand what you mean about "insulate with paper." Can you clarify that? The third, outermost layer, is for looks not insulation. You want something flameproof and that breathes enough so that steam from your bread doesn't condense on the inside of the decorative layer and turn your insulation and thermal-mass layers to mud. If you were going to use metal or concrete or tile or something you'd have to arrange for adequate ventilation between the oven and any relatively-airtight decorative and/or weatherproof layers. Alan Scott-style ovens are like that: If I remember correctly, they have a weatherproof cement-board shelter built over the masonry, but not built down tight to it. I live in Northfield, MN and I keep a tarp over mine all the time whenever it's not in use. Rain would turn the adobe back into mud. The same would be true for un-fired clay. Clay with absolutely no organic matter in it would probably hold up better in the rain than subsoil with some organic matter, but not well enough to go roofless and tarpless. Keep the questions coming. I love to talk about ovens. -Fritz

[materials]

does the mudd have any cement or mortar mix in it? bev

[materials]

thank you so much-i can't tell you how nice this looks and again your directions are great! thank you for sharing this and the great pics-i hope you,friends,and family are enjoying alot of pizza!!! bev

[materials]

sorry-it's filled with bottles, woodchips-etc.bev