Insulated Clay Pizza & Bread Oven

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Picture of Insulated Clay Pizza & Bread Oven
How to build a high-temperature pizza- and bread-baking oven from easily-obtainable materials and avoid the use of expensive refractory bricks. And to get it to heat as quickly as possible, get maximum benefit from your fuel, and use basic tools. And to make damn nice pizza!

Bill of materials:
100 or so Recycled bricks
250kg Pottery Clay - I got mine from a local pottery equipment supplier, who delivered to my doorstep.
4 x100 liter bags of Vermiculite - also known as Perlite - obtainable from a building supplier. £20 per bag
2 x 25kg bags of concrete mix
2 x 25kg cement mix
4 x 25kg bags of mortar mix
10 x 65mm-thick reinforced-concrete Lintels
6m of 1x4 wood for the foundation formers
Hard-core builder's rubble for the foundation
1 recycled Chimney or similar (eBay is can help you)
Thin wood slats salvaged from a wooden venetian blind (from IKEA!), or long twigs, for the oven dome former
Wallpaper paste
Some odds & sods...

Tools required:
Spirit level
Bricklaying trowel
Plasterer's float
Mixing Bucket
Power drill
Plaster mixing impeller

Nice-to-have tools:
Angle grinder with masonry disc
Air compressor & pneumatic chisel
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Step 1: How does it work?

Picture of How does it work?
The Working Principle
This oven works on the convection principle: A fire burns in the back of the oven. It is fed by the cooler air that flows in along the lower half of the cavity. The hot air and smoke rises to the top of the dome, and is then drawn out along the top half of the cavity through the chimney. The hot air in the dome causes heat to be radiated back to the ground and any pizza that may find itself in its way....

That takes care of the top of the pizza. The bottom layer in the oven is a material of high thermal mass (thick terracotta tiles in our case) that is heated up by the radiation from the dome and also by the conduction of heat from the fire. A porous clay-based material like terracotta is ideal as it temporarily absorbs moisture from the pizza base, which helps to give you a crispy pizza base. We intend to make proper pizzas here, not the thick, soggy things that those multinationals dish up, after all.

The fire is started in front part of the oven, and when it is ablaze, it is pushed into the back. The fire may appear to momentarily die because of the lack of oxygen, but the convection process starts to work within seconds and it grows again. The secret of keeping the fire going it to regularly feed it small amounts of wood, preferably using long tongs so that you can place the wood on top of the burning embers. You can test the convection process by dropping a few drops of water on the bottom layer of the oven: the resulting vapour should move into the oven towards the fire, not the other way around as you would normally expect.

There is no hard and fast rule of determining when the oven is hot enough. I just know it is ready for use when it feels much hotter than my domestic oven set to maximum temperature. I also measure the exhaust temperature on the chimney and when it exceeds 300 DegC (because that is how my temperature measuring device will go), then I know that the internal heat is well above that we are ready to go.

When the oven is ready, the cooking surface needs to be prepared by sweeping the any ashes either into the fire or out of the entrance using a natural bristle broom dipped in water. Then use a wet floor mop to pick up the remaining ashes off the cooking surface. You can also wrap a wet rag around the broom for the same effect.

You are now ready to bake your pizza.
elljay.q1 year ago
Brilliant! Great Instructable! What an awesome job you did.
Step 6 caught me off guard. LOL! :O
You are surely going to enjoy your oven for many years. Cheers.
gerrit_hoekstra (author)  elljay.q1 year ago
Ta very much!
bertdorf3.2 days ago

Ha - funny... I should have read the comments below before spouting off! Nice oven dude!

bertdorf3.2 days ago

Sorry mate but vermiculite and perlite are two completely different substances. But nice tutorial!

Taimur1 month ago

I love it!! I may use this as a small guide when I will build mine!! looks amazing!!

don't know your wood oven experience, but it tends to work better if you let the fire burn all till the wall's get really hot, at that time you should have nice embers like you would on a bbq make a nice pile on the entrance of the oven 1/4 - 1/5 of the height of the mouth, like this you can still access the food inside and when you open the oven door the air won't be too cold because it gets warm on the embers.

Like that you will maintain a steady temperature with low loss of heat!! Is great for the slow cooking and specially for bread!

(many years helping my granny baking bread, food and puddings in old brick oven) I hope it will help with the burns in the food =)

john.mckeag.14 months ago

vermiculite and perlite are NOT the same thing and vermiculite is NOT also called perlite. Vermiculite is mica that has been hydrated (soaked in water) and then heated quickly which causes the layers to expand like pop corn. perlite is a type of volcanic silica that is also hydrated and heated causing expansion.

alaamuhanna7 months ago
Nice project i like it very much and will try to make something like it
gerrit_hoekstra (author)  alaamuhanna7 months ago
Why, thank you sir!
Pure Carbon7 months ago

looks delicious.

ekiessling7 months ago
Awesome!!! love it...what was your total cost of materials?
rpotts27 months ago
Damn! I want to start making one of these just to get to step 6!
timpaniboy1 year ago
Perlite and vermiculite are two different things, perlite doesn't absorb water. Vermiculite is mica that has been baked to expand it. .
gerrit_hoekstra (author)  timpaniboy1 year ago
Aha, now we know, thanks! The expanded version is the one to use since it has better insulation properties.
JKPieGuy1 year ago
Vermiculite contains Asbestos, just to forewarn you. (Or atleat the really old stuff does, don't know about now.)
PitStoP2 years ago
Nice oven! I always wanted to make one in my back yard. Hopefully soon..
mistyp2 years ago
Congrats on becoming a finalist! Good luck!
mistyp2 years ago
That is quite the impressive project!
85rocco2 years ago
Very nice instructable! I've often thought about building a wood burning pizza oven, this is one to file away for future reference, thanks.

BTW, vermiculite and perlite are completely different products although, for this application, I strongly suspect they are interchangeable.
gerrit_hoekstra (author)  85rocco2 years ago
Thanks for the compli's! Well, what can I say? When I asked for vermiculite in a builders' supply shop here in the UK, the nice man behind the counter gave me a moster big sack that had Perlite written on it. Maybe he goofed? :-)
Both are widely used in the horticultural industry, as far as I know, only vermiculite is used in the building industry so if you got yours from a building supply, it's probably vermiculite, it's difficult to tell for certain from your pictures, but that is indeed what it looks like to me.

Perlite is white and crumbles quite easily if you squeeze it between your fingers, vermiculite is brownish and a little spongy when you squeeze it between your fingers, also, perlite absorbs water much more readily than vermiculite.

In any event, both are inert, heat resistant and highly insulating when dry so I think either should work well for this application, perlite would just take longer to dry out and release more steam while drying.
85rocco 85rocco2 years ago
An addendum to my last comment, I did a little searching on google and it turns out that perlite is not only a generic product name but also a corporate name and Perlite sells both perlite and vermiculite, that could explain why a bag of vermiculite would say Perlite on it.
cheezstake2 years ago
This is wonderfully written! I have saved this for future use. Cheers!
Extremely detailed and well documented! I'd be crazy not to replace my stove with this.