starting my clay oven.....................or maybe not.

[dmun]

Re: starting my clay oven.....................or maybe not.

Can I just interject here for a moment?

Then you saw the packing of 200 mm of decomposed granite [packing gravel] in a 'well' in the oven base to act as a 'heat bank' to absorb the heat from the floor so that it 'gives back' once the fire is out or removed.

Eight inches of solid masonry under the floor, even if it's insulated underneath, means that your oven will have to be fired all day to get up to pizza temperatures. (It might work if bread baking is your only goal, and you need a cool floor to prevent loaves from being burnt on the bottom.) This plan is only good if you are going to fire your oven every day, and that mass won't be leaking unneeded heat for the next two days.

I was going to use Vermiculite with cement fondue mix straight over the castable to a thickness of about 75mm for the insulation layer.

Three inches of vermiculite concrete, by it's self, isn't nearly enough. It's the amount that builders here put over the mineral wool blankets to create a smooth surface for stucco.

The last few posters on this thread are new to the site, and I want to welcome you. We like new people and new ideas. But we don't like old, discredited ideas, like huge "heat banks" under oven floors. Nothing is sadder than a builder with a new oven that won't get up to temperature. It's a lot of work to build an oven, and you owe it to yourself to do some research on this site and to find the ideas that are proven to work.

[Balthazar]

Re: starting my clay oven.....................or maybe not.

Thanks dmun. I'm researching my butt off, but just seem to find conflicting recommendations a lot of the time. I just want to do this thing right the first time.
The 75mm of vermiculite cement straight on the hotface layer was on a TV segment I saw, but obviously, I need to go with the ceramic blanket as well.
Thanks again.

[havefun]

Re: starting my clay oven.....................or maybe not.

Hello everyone.

I had been planning to build a lo-tech clay oven, but after studying this forim, I am coming around to the idea of a more permanent brick oven.

The thing that set the ball rolling for me was a TV programme that showed the construction of this oven, and I thought "I can do that"

Here's the link: au.video.yahoo.com/watch/2972929/8334268

I'd be very interested to hear if anybody else has built this type of oven, and whether they were happy with the outcome. I am a little worried, as the base is constucted with clay pavers rather than fire bricks. I have held a blowtorch to a clay paver for a good 20 minutes, and there was no sign of stress, or any "spitting".

I am almost at the end of constructing my base, so any feedback would be most welcome.

Thanks

Mike

Hi Mike am also in the proccess of starting a clay oven and what i remember when i was a kid people in my village used lost of empty old bottles on the bottom of the floor then filled everything with clay to get a flat surface usually on a biggish over about a foot thick of bottles usually there was a small storage space under for the wood n it never got too hot if i remember right hope it helps GL takis

[berryst]

Re: starting my clay oven.....................or maybe not.

lesson one:

listen to Dmon,

lesson two;

I had 6 inches of firebrick in the floor and under that I insulated heavily.

But to bring the oven to temperature and maintaining Pizza temps of 750 is a trick. Because the floor is not mortared I simply removed a whole 2" layer.

This took all af 5 minutes. I can replace it if I choose.

I thought I was going to do a lot of baking but I simply do not. Pizza is more fun and that is just the way it worked out.

SO INSULATE HEAVILY. Don't over brick unless you primarily want to bake.

[Wood fired oven workshops]

Re: starting my clay oven.....................or maybe not.

In answer to Mickey-T
The use of clay pavers in the low tech. oven is in keeping with the overall low cost, easily available materials concept of that oven.
Firebricks or tiles made from fireclay are designed for, and are used in, situations where very high temperatures are expected, such as kilns and furnaces.
They are usually capable of coping with temperatures in excess of 1200 degrees centigrade because of their high alumina content.
A house brick [or fired clay paver], on the other hand, is fired usually to 1050 degrees plus but a few, especially white bricks, are capable of withstanding temperatures of well over 1200 degrees - I've used them in ceramic kilns for years.
When it comes to wood fired oven temperatures a house brick or clay paver is certainly adequate in coping with the temperatures and use for general intermittent household purposes.
My house is 120 years old and the fireplace is built of common red bricks which were 'burnt' on site from local clay. Despite regular use over the 28 years of my occupancy reaching temperatures high enough to warp and buckle a number of heavy wroughtiron grates the bricks have shown little deterioriation.
I've know one 'low tech.' oven that has a paver floor and it has been used for years without any sign of problems.
As there are numerous qualities of pavers [as there are in firebricks] go for the harder fired, lighter coloured ones.
Avoid the vitrified clay paver [generally called a tile] as these will certainly crack because of their 'glass like' fired structure.
I am not advocating a substitution of house bricks or pavers for quality firebricks or refractorary castable, as these are undoubtedly better, but if you are looking for a much cheaper alternative for a low tech. approach they are perfectly adequate.

[Mickey-t]

Re: starting my clay oven.....................or maybe not.

Hello again everyone.

Well, I have had my oven complete for a good 6 months now, and I have used it at least once a week, and it has been excellent.

I used clay pavers for the floor, and indeed followed the original plan, with the only exception being that I placed a good 120mm of Perlite under the oven floor rather than the crushed stone. I also finished off the dome with a layer of sand/cement screed on top of the insulation. just for appearances. The outer layer stays cool when the oven is up to full temperature, so obviously it is well insulated.

I cannot fault the oven one little bit. It cooks pizza to perfection in a couple of minutes. We have had countless friends try the pizza, and they all say it is the best they have tasted. Just tonight we have had tandoori chicken and sheek kebabs with naan bread, and again, the results were excellent. I also cooked a full chicken for tomorrow, along with some bread with left over dough.

I am very happy with the oven and very grateful to the man who inspired me, AND to all the posters who pointed me in the direction of insulating under the floor. We are in the process of selling our house, and I am already looking foward to building the same oven in our next house. I thought about a brick oven next time, but, honestly, this oven is SO good, why would I want to change anything?

Cheers everyone

Mike

[arevalo53anos]

Re: starting my clay oven.....................or maybe not.

Mike:

Even a little late, congratulations!
I have my own brick oven and I happy with it. However, my first thinking was to build a clay one (like the one that my brother had) and from time to time the ideia come back to mind.
Nowadays I am thinking to build a little clay oven, just to 'feel' it and then pull it down.
I could not see the video of your first message.
Could you put any pictures of your oven in this thread.
I will appreciate it.
Thanks

Luis

[Mickey-t]

Re: starting my clay oven.....................or maybe not.

Hi Luis

I've just posted 3 photo's.

If you click on photo's, and then "Finished ovens" then look for Mickey-T's oven. I've just put them on tonight, so I should be on the front page for a day or two.

[Wood fired oven workshops]

Re: starting my clay oven.....................or maybe not.

Hi Mickey-T and others,

I'm glad to hear your oven is such a success.
You, and others, may be interested in submitting your favorite wood fired recipes to 'Earth Garden Books' for their new booklet 'Wood Fired Recipes' which will be a follow up to their very popular 'Back Yard Ovens'.
They are offering 5 free copies of the finished booklet plus a book voucher from their wide selection of, mostly alternate lifestyle and practical guide, books. The deadline is 1st May.
You will find details on their web site Earth Garden - sustainable living with country and city alternatives or you could speak to Fiona on 03 5424 1743
Although, I presume, it was a call to Aussie oven owners they may be interested in hearing from 'internationals'.

[Kittcatt]

Re: starting my clay oven.....................or maybe not.

Hi,

Does anyone that has built the BH&G oven have a rough estimate of how much it cost to build?

Thanks

[havefun]

Re: starting my clay oven.....................or maybe not.

Hi,
its defficult to say how much as that will depend greately what kind of an oven you want a simple oven my mate build almost cost him nothing he got the clay from a skip got a piece of shatering ply again from a skip put a layer of flettons normal bricks about 30p each got the straw from a farmer he knows n bingo he had an oven for ?30 mine so far is cost me over ?200 n its not finish yet, but so far i dug a shallow fountation put dump proof plastic layed about 6 inches of concrete with some steel builded bricks to chest level put slades for another dump proof on the bricks rendered the inside layed screed on the floor with another damproof plastic got some ply n timber build a frame round it used some reinforcing steel layed what would the oven floor be build on as i intent to store firewood under the over i will need more concrete round the thermalites i be using for insulation to lay the fire bricks on so far i spend over ?200 lots of hard work n still need nearly ?100 for fire bricks maybe ?10 for thermalites some fire clay some fire mortar n straws n who knows if i'll cook any better than my mates but i hope it will last a long long time once i finished i will add it all up n send some plotos as the work progressed its also a personal satisfuction as each over its differentely build by each one of us most of the hard work is accually buying n currying the materials through the house to the back garden so whatever pls do allow extra time for finishing the oven
n best wishes with it Takis

[abncraig]

Re: starting my clay oven.....................or maybe not.

does any one here know where I could source the clay or powdered clay and sisal rope. I am in Perth and not having any luck with the pottery places might be trying the wrong ones any opther ideas to who stocks this?
any info would be greatly appreciated
thanks Craig

[havefun]

Re: starting my clay oven.....................or maybe not.

hi Greig here in the UK i managed to get hold of a lot of clay as they dug it out of the fountations my problem after was getting it to a working mixure not easy in the end i soaked it in a big bucket for 4 days n then got an attachment ona drill n mixed it that way once it was mixed nicely i then added the sand n after started mixing the straws in the mixure by hand my big mistake i took the sand out too early n it colapsed couple of hours later so this time its been just over a week n haven't taken the sand out even it feels solid i might in the next day or 2 i tried many times to upload photos as the work progressed but they never loaded gl mate it will give u lots of satisfuction knowing u did it all yourself in the end

[Johnny the oven man]

Re: starting my clay oven.....................or maybe not.

does any one here know where I could source the clay or powdered clay and sisal rope. I am in Perth and not having any luck with the pottery places might be trying the wrong ones any opther ideas to who stocks this?
any info would be greatly appreciated
thanks Craig

Craig, call SILA on 08 94553133. They will help you.

[Mickey-t]

Re: starting my clay oven.....................or maybe not.

Haven't checked out the site for a while....too busy cooking pizza.

If anyone in Perth needs ball clay. There is a pottery supplier in O'Connor that stocks it. They are in Yellow Pages and they are the only supplier in Perth (to my knowledge). You will need two large bags (you'll use a bag and half)

I ended up using 8 bags of Perlite, available at hydroponic suppliers.

I've built two of these ovens now, and would recommend it to anyone.

Good luck.