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jpmort 07-22-2009 09:39 AM

low dome clay oven
I think I have decided to build a low dome clay oven, primarily for pizzas. Like most people I have spent ages reading through as much as I can find, and this is where I have got to:

I am looking for 36'' internal oven diameter, as I want it to heat up quickly, I am pushed for space, and a pizza at a time is fine with me.

I am going to build it directly on the ground, on a bank of earth. I will flatten the earth and make a solid bed for the oven.

I am not sure if I use clay from the soil, or buy some...

I will use lime mortar for the external render, for waterproofing. NHL 5.

The oven floor, I have some large terracotta tiles I hope to use.

So, if anyone would like to advise on anything I have listed that would be great. My main questions are:

1. I am placing the hearth on soil. What insulation would you recommend, and what sort of a base to keep it all from moving?

2. Can clay heat up enpugh to give 400C degrees?

3. Will clay be strong enough for a low dome?

4. Am I mad?

Many thanks for any responses...


Archena 08-29-2009 08:04 PM

Re: low dome clay oven
Okay, so this isn't the most prompt reply ever...

1) I would guess a sand base will do as long as it is thick enough. Definitely need to consider mortar if the tiles are small but as long as the walls contain the shift sand should do for large tiles.

2) <Plugs 400C into temperature converter> 752F? Yep, it should get at least that hot - perhaps hotter depending on design.

3) Low domes are difficult for any material. I would guess you'd need to use straw (adds tensile strength) and whatever you do don't even think about removing the core until it has had at least a few days drying time. I've seen people begin firing as they clear the core but I'm not sure about how that's done.

4) Dude, rather than use the nice oven in your house you want to bake pizza in your backyard in an oven fired by wood - of course you're crazy! Welcome to the club! ;)

jpmort 09-03-2009 04:17 AM

Re: low dome clay oven
Thanks for that reply, and I appreciate it despite the delay!

Due to the weather here and the problem I have had in getting clay, I am postponing the project until next year. In the meantime I will gather up more knowledge. In the meantime I am still making pizzas in my barbecue.

I found your information informative and reassuring... I have decided to try a low dome with clay and I will ensure that the clay is dry before removing the core! Good advice. I am thinking now if I need insulation or not. I am only going to fire it up to make a few pizzas at a time and maybe the insulation is not so critical with me.


dmun 09-03-2009 04:37 AM

Re: low dome clay oven

I am thinking now if I need insulation or not. I am only going to fire it up to make a few pizzas at a time and maybe the insulation is not so critical with me.
You MUST insulate! Below and above! There is no greater truth in oven building.You simply won't make "a few pizzas at a time" if you can't get it up to pizza temperature. Even the ancient Romans insulated their ovens with tufa. To do otherwise will be to burn forests of wood, and produce only smoke.

jpmort 09-03-2009 09:03 AM

Re: low dome clay oven
OK, thanks for that... I have now decided I will insulate.


luca 09-04-2009 03:25 PM

Re: low dome clay oven
I beg to differ on the insulation question! I built a clay only oven about five years ago simply out of our native clay soil here in Kentucky (like anyplace, you have to dig down under the topsoil layer to find the'll know it when the going gets tough!) I built it on a brick pedestal, with a sand base covered with firebricks as the floor (but your tiles will work fine as long as you have a good sand base underneath). I made a barrel vault style, using a sand mould, with an inside cooking floor of 24 inches by 36 inches; an entry door of 18"; and a door height of 8.5 inches. After the clay hardened for about a week, I removed the sand and lighted a slow curing fire. I now cook pizzas regularly and have never insulated the top, which is still exposed (I built a wooden A frame over it with a 6-12inch gap to keep the rain off of the clay). The oven walls are about 5-6 inches at the base, and 3-4 inches at the top (remember that wet clay flows, and if you mix it too wet as I did, you will get some flowing, with the bottom ending up thicker than the sides. But no matter, it still works great!). Finally, on the insulation question, it takes about 2-2.5 hours to fire up, and I do keep a fire buring in the back of the oven at all times, so that I can increase the heat by adding a small piece of wood right before cooking the pizza, which works fine. (I have even burned the bottom of some initial pizzas by getting the oven too hot). The only thing this oven won't do is cook over 2-3 days later as the brick ones will, but I only use it for pizzas (90 seconds to 2 minutes depending on the heat) and some barbequed meats (covered with foil and a door on the oven overnight). If you can't find my pics on this site, let me know and I'll post some more. Happy building!!!

dmun 09-04-2009 03:58 PM

Re: low dome clay oven
A brief note, not to get into an argument: Kentucky is covered in forests, where the UK was pretty much deforested by the 18th century...

luca 09-04-2009 05:25 PM

Re: low dome clay oven
Here is the thread with pics on the clay oven:

As for clay in the UK, the best way to find out is simply to dig! (I read somewhere that you should be able to make a fist sized ball with the clay, and then drop it from waist height without it falling apart; then you know that it has the cohesive properties necessary to be made into an oven. I did this and found that it was true!).

Archena 09-04-2009 05:38 PM

Re: low dome clay oven
Devon* is considered prime 'cobbing' country (houses instead of ovens!) and is still where you find the most cob houses including those dating back to the 16th century! :cool:

I live in the danged Black Belt - and reach clay in only one shovelful! :mad:

*AKA Devonshire - beats me as to which one to use when - I'm from Alabama, not Britain.
**None of the above has much to do with anything but I'm in a trivia mood!


I'm staying neutral in the insulation wars - I've read good cases for both sides. :)

marklewis 03-31-2010 07:20 PM

Re: low dome clay oven
Did you ever build a clay oven???
Check out my tread link: I built one and have used it and will next be insulating the dome. I have some expertise and may be able to help answer your questions.

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