How to Build a Pizza Oven.
Part II

Today is the most exciting day of your life.  You’re going to learn How to Build a Pizza Oven!

 

When last we met, in part 1 of this series, I had built the base and the sand form for my cob oven and lost my funny bone. It’s currently buried beneath a layer of pizza fat.

Now it’s time to make the actual cob for the pizza oven. The cob is the material of the first layer of the oven.  The cob is the layer that will heat up (the thermal mass).  The insulating layer, which comes after the cob is what holds the heat in.

As I keep saying, these tutorials are meant to be a reference to how I built my oven. If you want to build your own I highly, high, HIGHLY recommend you buy the book Build Your Own Earth Oven and watch architect Sigi Koko’s 4 part video series on How to Build a Cob Oven.

The book will give you accurate measurements for your oven so it will vent properly, and accurate amounts of how much building materials you need for various sized ovens as well as a ridiculous amount of pointers.  Sigi’s videos will have the book all make sense and give you a great visual reference.

My posts, will give you a good idea of the work involved and the confidence that you can indeed do it yourself.

Also there’s a lot of stomping involved so it’ll give you great legs.  Don’t get excited. Those will disappear when the stomping stops and the pizza eating begins.

 

Mixing-cob-1

 

The materials to make cob.

Clay

Sand

Straw (straw is only used in the insulating layer of cob)

One of the reasons I decided to go with a cob oven for my pizza oven was because the materials are either free or cheap.  My town happens to be filled with clay, so I knew all I had to do was dig up my mother’s yard to find enough clay to make an oven.  Sand, well that’s cheap enough and straw goes for around $4 a bale at my local feed store.

If you watch the videos and read the book I recommend they describe perfectly how to see if the clay you’ve dug up is pure clay, or clay with a certain amount of sand content.  Mine, as it turns out, was fairly pure.

The reason you need to know this is because the amount of sand you add to your clay will depend on how much sand the clay already has in it.  You’re creating ancient cement basically.

The clay and sand (in the required proportions), I believe mine was one part clay to 3 parts sand, are mixed together.  Not an easy feat.  Or feet.  You stomp and jump and turn and toss and jump some more to fully integrate the sand into the clay.

 

Mixing-Cob-2

 

Your mixture needs to be sticky; so enough clay that it will all stick together, but enough sand that once it dries it won’t crack apart.

Mixing and testing cob





Is making a cob oven a pain? Yeah. A little bit. Is it fun? You bet. Worth it? DEFINITELY. Here’s a quick look at how to mix your cob and test it for the proper consistency

You can see in this next picture that I’ve placed a layer of newspaper over the sand dome.  This is so when I go to dig the sand out to crate the interior of the oven, I’ll know when to stop digging.  Once I hit newspaper I know I’ve made it to the cob layer.

 

cob-oven-first-layer

 

Creating the outside of the oven (the cob layer) involves grabbing a handful of the mixture, plopping it down and smashing it with your fist to make it nice and tight.  This layer needs to be around 4″ thick.  Just keep plopping and smashing.  Plop and smash, plop and smash.

 

cob-oven-first-layer-2

 

You’ll know you’re doing a good job when you look like you joined Fight Club.

 

bleeding-knuckles

 

Don’t worry about it.  Suck it up.  Show those knuckles off.  You’re knocking out a pizza oven, Sugar Ray.

 

cob-oven-bleeding-knuckles

 

 

Once the cob layer is done, you need to let it dry for a couple of days.  Just enough so it won’t collapse when you start your next step.

 

Which is cutting out the door of your pizza oven.

The door needs to be specific measurements (again explained in the book) in relation to the size of the oven in order for the pizza oven to vent properly.  If your proportions are right the smoke from the fire inside the oven will roll up to the top of the pizza oven, then roll right out the top of the door.

The smaller your oven, the smaller your door needs to be, the smaller the pizza you’ll be able to fit into it.  Bigger oven means bigger door which means bigger pizzas.

My oven’s door will barely fit a 12″ pizza peel.  I can fit 2 pizzas in it at a time.

 

cob-oven-cutting-out-door

 

Once your door is dug out you’ll discover your original sand form …

 

door-cut-out-cob-oven

 

Which you can now dig out.  Once you dig that out, you’ll have something that actually looks like a genuine wood burning oven and you’ll be very, VERY excited.  So excited in fact that you’ll spend a lot of time running, squealing and shaking.

 

digging-out-sand-cob-oven

 

 

It’s a pizza oven.  It’s a bread oven.  It’s the focal point of your backyard, neighbourhood, TOWN, p r o v i n c e, COUNTRY, P L A N E T!

 

cob-oven-first-layer-complete

 

And you built it. With your own bare hands.

 

scraped-knuckles-fight-club

 

 

Let’s move onto the final step of How to Build a Cob Oven, Step 3!

 

64 Comments

  1. Chelsea says:

    Hi Karen,

    I’ve read this post a million times as I dream of building a pizza oven and do not want to spend thousands on something I don’t even know how to cook in yet!!

    I had a wondered if living in a wet and also snowy climate do you have to cover your oven from these elements? If not, without that protection has it held up okay?

    Can you paint the lime layer once it’s finished.

    Also I am curious as to why there is no chimney?

    Your projects always turn out so beautiful. Thanks for sharing with us.

    Chelsea

    • Karen says:

      Hi Chelsea. The only time I cover up the pizza oven is just before winter. You don’t want it to get rained on, then have the rain freeze because any rain that gets into the small outer cracks of the oven will expand, cracking them more doing a lot of damage. There’s no chimney because it’s designed in a way (you have to be very specific in your measurements) that it doesn’t require one. A draft is created that pulls the air and smoke out through the top of the oven door. As far as painting the lime plaster, you can do it, I’m just not sure how. Good luck! ~ karen!

  2. Dee Rath says:

    I’m a potter by hobby, so this project really speaks to me! Couple of things – couldn’t you use a paddle of some sort, like a 1×4, instead of your knuckles? Also, you can buy moist clay, but it is certainly a lot cheaper to dig your own, especially considering the quantity this must take. I read the whole thing but I don’t remember – did you say about how many pounds of clay you used all told?

    • Karen says:

      Hi Dee! You probably could use some sort of tool, but I find I do my best work when I’m using my hands as a tool, lol. Just wearing some good, fleece lined gloves would probably work but they’d also become heavy with clay. I actually have no idea how much clay I used. Around 3 or 4, 5 litre pails if I remember correctly. The amount you use also depends on the size of oven you’re going to make. If you live in an area that has diggable clay then that’s the easiest, cheapest and best way to go because it already has a certain amount of sand mixed in with it. You just have to figure out how much through a water shake test and add as much more sand as you need. ~ karen!

  3. Zeenat says:

    I love your cob oven, actually I am in the process of building mine, myself. I love the feel of earth. Mine is about 30 inches at the base, how high/ should the door be. One more question as I laid the bottles at the base I covered it with clay and sand but it was not too wet, will that be alright. Thanks and congrats once more .

    • Karen says:

      Hi Zeenat. Congratulations on building your oven! It sounds like you may need the book I recommended though. “Build your own earth oven”. It answers all of the questions that people have while building a cob oven. (I had about a billion questions during the process) Like how high your door should be for example. It’s all based on mathematical equations and proportions that would be in the book. And if you don’t do things properly your pizza oven might not vent properly, or even worse, might collapse, which would be horrible after all your hard work. I can’t answer your questions (because I don’t know the answers for sure) but I can tell you the book will answer all the questions that will pop up. ~ karen!

  4. Brilliant! In my continuing mesmerizing research, based on what I learned about horno ovens at the Red Willow Reservation, a horno oven and cob oven are basically constructed in the same manner except they call the material of clay, sand and straw adobe.

  5. Barbie says:

    Ok….I know I’m late in response….been gone…..and …I KNOW I’m supposed to comment on your pizza oven and all and YES it is awesome and you are a stud! Of course I have acknowledged this before! LOL….but seriously you look GREAT! In great shape! LOL THIS is what I noticed! LOLOL You sexy thing!!!

  6. Nancy Blue Moon says:

    I seriously did not know that you could levitate..I am really impressed now..

  7. JB says:

    But, wait…where does the hay come in? Didn’t you say cob was clay, sand, and hay? I saw you mixing the clay and sand, but did I miss the part where you add hay?

  8. Sheri says:

    So this is how you fed yourself while the kitchen reno was in progress.

  9. DD says:

    I am so pleased to see this, I have been dreaming of a pizza oven but the kits are quite hideous. Seriously I thought cob was made with corn cobs…will you tell us how many hours you put into this endeavor?

  10. Traci says:

    Alright Karen, you’ve inspired me. Or rather, I now have “she did it so I can do it too “syndrome…I’ve been toying with the idea of using cob to create walls and/or planting beds in my backyard but always chickened out. Really, it would make sense since I need to dig out a lot to level it which will give me all the clay I need. It just seemed too hard or too much work to be possible. Now you’ve gone and made it look possible. Of course, now I also have my heart set on building a pizza oven while I’m at it. This will all have to be a project for next year though, because right now I have a very clingy newborn and I don’t think digging in the heat while wearing the furnace that is my giant baby (seriously the kid is 14 lbs. 10 oz. and not even 3 months old yet) will be very possible. Now I will go back to obsessively reading about cob a la 2 summers ago and make a real plan. Stop me before I build a cob play house for the baby too! My husband is really not going to be happy about this.

  11. Liz says:

    geeking out a little bit about the clay…er cob. I guess we’ll learn more tomorrow, but I’m super impressed that the structure was able to support itself after just 2 days of drying! Curious about how you prevented collapse, and now a year later…cracking. Did you have to let all the moisture leave the cob before putting on the insulating layer and the plaster? Maybe I should just read the freaking book

  12. monica says:

    You kick serious butt!
    As a fellow pizza lover, I was inspired to make this for you. 😉

  13. leslie says:

    My husband has been in the process of “making” a pizza oven (we call them hornos here in New Mexico) for oh… about 2 1/2 years now. We have our pile of bottles for insulation and he has the cinderblocks all piled up to create the base and he keeps rearranging them according to different ideas of desired height, design, etc. I just really wish he would switch to legos instead- same activity but smaller, lighter and neater. Would it be wrong of me to finish his oven while he’s out of town for a week?

  14. Serduszko says:

    OMG! This is fabulous! You are such an inspiration!!

  15. Rondina says:

    I watched the YouTube videos and they were great. Very detailed. I wish you had filmed the part where you mix the straw with your feet. That would have been strong competition for Lucille Ball’s infamous grape-stamping scene.

    I’m noticing the plants on the wall in back of you. I don’t remember that lesson.

    • Doug says:

      Just ordered the book. Love that oven, going to build my own. Of course I’m 5 years late reading this blog. Ps…. you still have your funny bone .

  16. Olga says:

    I still can’t get over the fact that you kept this secret from us a whole year! A YEAR, Karen! How could you do this for a year? We come here and live imaginary life with you, thinking we like a good neighbor, we know everything about you, and know what underwear you wearing (or not wearing) today and then this? Secrets? Secrets = lies.
    Now reading your post I think I might reconsider my husbands idea to built pizza oven. I always thought they look dumb, like a bald head sticking out in the yard. And I think it’s one of those things that I might use one time and then back to our BBQ grill. Kind of like cheese press that I want to buy so bad lol. Your looks very authentic and Artisan and you make it sound like it was a weekend project. lol

  17. Patti says:

    Awesome and dare I say looks easier to do than I thought!

  18. Ev Wilcox says:

    Wonderful! And a great way to house your funny bone till you need it again! It is a smashing good focal point in your patio fairyland!

  19. Karol says:

    Oh, Honey! Those thigh muscles!

    • Karen says:

      Oh those are gone now. They’ve been replaced by what appears to be partly melted mozzarella cheese. ~ karen!

  20. karen l says:

    OK – I’m hooked! Question for you – do you think it’s easier to find a source for local clay to dig or order pottery clay online and mix yourself? I’m all about quick, easy and cheap projects, but – if I dig holes in somebody’s yard I guess I have to then refill those holes with something other than trash with fake dollar store grass on top!

    • Karen says:

      It depends on where you live. If clay is abundant, just go dig it up. I got mine when someone was redoing their backyard and had dug up a bunch of clay. Then when I needed more I just dug under a tree in my mother’s backyard where you’d never notice it was gone. When you dig up your own clay though you have to do a test to see how much clay is in it compared to sand. That lets you know how much sand you have to add to your mixture. If you buy clay you’d be buying powdered clay that needs to be hydrated. ~ karen!

      • Shauna says:

        how do you test the clay from a yard? We live in San Diego where most yards are made of clay, and rocks. I wouldn’t know how to test it though to be sure of it’s clay ratio.

        • Karen says:

          Hi Shauna! I wish I could remember, lol. Basically you put a sample of the “dirt” into a mason jar and shake it and shake it if I remember correctly. It will then separate itself over the course of 24 hours and you can actually see the clay layer and the sand layer and therefore know how much of each there is. I have a feeling one of the videos that I suggest you watch talks about it. ~ karen!

  21. Miriam says:

    I’m curious about the ratio of effort to pizza. How many pizzas must one make and eat to counter the time and effort necessary in making the cob pizza oven? Do you have to stop making and eating pizza once balance is achieved or is there another project that counters pizza consumption? Finally, is fired pizza that much better than the frozen stuff?

    • Karen says:

      Miriam – In answer to your questions a) You must begin a new project immediately in order to maintain balance. And b) How could you ask such a thing! ~ karen!

  22. This is fantastic Karen!

  23. This is so cool and I’m so impressed with your work. Reading your daily how to’s has me hooked like waiting for the next book in a series.

    I’m curious. How do you get the firebricks so clean? Do you brush the sand out, vacuum it or just cooks lots of dough that makes the sand stick to it?

  24. Tigersmom says:

    I can only imagine how cathartic this must have been and the thoughts going through your mind as you were punching…

    This is the most impressive lemonade from unsolicited lemons ever!

  25. Jody says:

    Wow. You tackle jobs that most would never consider. And you got a sand pedicure too. How did it compare to the fish pedicure?

  26. Louise says:

    She certainly does look good, doesn’t she? Damn, if this video gets out to large groups of men, imagine the crowds at her house! Pizza and a smart, good-lookon’ woman, yee haw!

  27. Grammy says:

    I confess that mixing and kneading the cob with your feet seems to me like the most fun anyone could have standing up. It is, though, criminal how good you look doing it.

    Great tutorial.

  28. Kristin Ferguson says:

    Hi, Karen! Here’s a video of me making a pizza in less than two minutes in my pizza oven:
    https://www.youtube.com/watch?v=jehKW3XS6Hw
    LOVE your oven! I think you should get a digital laser thermometer to test the temperature of your oven–not because you need to, but because it’s super cool and geeky. They’re a little bit “spendy” (as Kiko Denzer would say), but it’s so cool to be able to know how hot the interior of the dome is. Great job on this and on everything else in your life!

    • Kristin Ferguson says:

      P.S. Did you notice Tippie the hen waltzing by just as I’m about to put the pizza in the oven? She’s such a diva.

      • Karen says:

        Watched it! Very nice. Tippie is very pretty! And you keep WAY more flame in yours than I do, even for pizza. I’ll try that for my next firing. I always leave coals but not nearly that many. Pizza looked great! Love broccoli on a pizza. Do you use pizza flour for your dough? I was given some by the very nice people at Cumbrae’s market where I live because they’re Italian and they heard I was making wood fired pizzas without using pizza flour, lol. I’ll try the dough out of it when I do my next firing too. Which after watching your video might just be tomorrow. 🙂 ~ karen!

        • Kristin Ferguson says:

          I don’t use Italian pizza flour. It doesn’t have enough gluten for my style of pizza. As you can see in the video, I stretch my (very soft) dough over my knuckles, and it would fall apart if I used doppio zero. If you spread your dough on the counter top, it would work. I like to take my cat’s temperature, too.

        • Karen says:

          I work it over my hands and spin it. I don’t roll my pizza dough. Oh well. I”m gonna give it a shot anyhow to see how it works. Apparently you get great bubbling on the crust from it. ~ karen!

    • Karen says:

      I”ll watch the video now Kristin! Thx! ~ karen (oh … and I thought you knew me better than that. Do you really think I’ve had a wood fired oven without owning a thermal thermometer! As if, lol! I routinely take the temperature of my cats noses.)

  29. Deb says:

    You inspired me to make pizza from scratch tonight…. We are hooked………

    • Karen says:

      Excellent! Did you do it on your BBQ? Did you use the dough and sauce recipe from my site? Don’t worry I won’t be offended if you didn’t, lol. ~ karen!

      • Debbie says:

        No – was store bought pizza and a copy-cat recipe for Boston pizza’s perogy pizza – hubs favorite – he said it tasted better than from Boston Pizza ☺

        My love affair with pizza has began…… just printed your recipes and will be making the dough tonight and pizza tomorrow night…….. thank you

  30. stephanie says:

    One word …. gloves!

  31. Amber says:

    oh-dear-god-and-all-the-little-kitties-you-are-crazy.
    My gas station sells pizza, for 2$ a slice on Tuesdays.
    Now my mother will make me make this for her. Thanks for nuthin.

  32. Kathline says:

    Awesome! I’ve always wanted a backyard oven. I imagine the s’mores are every bit as delicious as the pizza.

  33. Edith says:

    Karen – YOU ROCK!

    What will be next? I can see you becoming a Bee Keeper!

  34. Niki Dee says:

    Pizza oven book on wish list. Just have to finish building my pallet coop and pallet green house. Cob oven may be a next year project BUT that gives me time to toughen up my knuckles.

    • Karen says:

      Niki I find a good cheese grater is the fastest way to go in terms of knuckle training. ~ karen

      • Niki Dee says:

        And thank goodness I already own one. I’d hate to figure out how to build a cheese grater out of pallets!…. no, that’s not a challenge. 😉

  35. Janet says:

    You are seriously killin me over here…..

  36. Kat says:

    Next to the coop cam this is my fave blog, tutorial or whatever you are supposed to call it! Until you make another one! Is that the same knife you used in that glue add for the Brits? I liked that one also.

  37. Shauna says:

    Question: How do you manage to get every last bit of sand out so that your oven won’t be forever be dropping sand onto your pizzas?

    • Karen says:

      Hi Shauna – There’s the layer of paper in between the sand and the cob. So you dig out the sand, peel off the paper, and you’re left with the cob. Whatever paper you can’t peel off just gets burned away during the first burn. ~ karen!

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