A build from the North

[bighairyal]

I've discovered the best clay I've ever seen - it's a lovely buff colour, smooth, homogenous, unimpeded by topsoil, and comes in almost limitless supplies.

Sadly, it's 30m below water 12 miles off the coast of Harwich - and if I was seen taking a bucket and spade down with me on my dives, the client rep would probably kick our entire company off the job.

C'est la vie......

[cannyfradock]

Al

sounds like good stuff, but there's no need to go to them depths....nor them lengths to some decent clay. Find your local "turf",,,soil suppliers. They will usually sell CLAY. In my part of the world ...South Wales, you can buy clay at £12 per ton....

....just another option.

Terry

[steveastrouk]

Mar 20, 2012 7:04:55 GMT bighairyal said:

Sadly, it's 30m below water 12 miles off the coast of Harwich - and if I was seen taking a bucket and spade down with me on my dives, the client rep would probably kick our entire company off the job.

C'est la vie......

hehe. Love the punchline.

[bighairyal]

As predicted, I've been home for over a week now and thanks to weather, have only this morning have been able to get out and tend to my oven. It is now raining again, hence why I'm posting and not building

Over the past week I've been out and bought:

15x 2" thick firebricks (they are the yellow ones, but do weigh 3kg each, so confident-ish they'll store plenty enough heat)
Vitcas high temperature tile adhesive
B&Q quarry tiles

These were all thrown down this morning in such a fashion as to create an oven hearth. You'll note from the photograph below that I'm steadfastly maintaining my 'rustic' approach to building, and am in no danger of showing the rest of you up :-)



Next step will be to grout the tiles. I read on the Vitcas adhesive tub that it's not suitable for this purpose - anyone know why?

Once that is done I'll be seeing about erecting the dome. This will consist of 4" of clay/sand mix and 3" of vermicrete. I shall not be bothering with the traditional 3rd clay layer, as the oven dome will be largely hidden from view with a little wooden roof arrangement. The whole affair may end up being rather lightweight in comparison to some of the other ovens seen on this forum, but I still believe it'll do fine for cooking pizza with a fire still going, then clearing out for a loaf of bread and then an overnight stew/leg of dead beast.

Size wise, the internals are going to end up being approximately 25" port to starboard by 28" bow to stern. Not enormous, but large enough for my needs - and it should heat up nice and quick.

Out.

[surfingspider]

Loving the clay build. and I am glad you found my post about my oven helpful. I have one consern though if you dont mind me mentioning it.

is vermicrete breathable?

In the book I based my build on "Kiko Denzer - Build Your Own Earth Oven" He warns about water proofing the outer side of your clay oven as clay ovens breath. If you put a waterproof layer on it cant, he says it will store the moister and eventually the inside layer of clay will collapse.

I would be worried about mixing the styles of building. If you mixed the vermiculite with clay slip i think you would be fine. On the other hand vermcrete might be very breathable with all the air pockets and everthing will be fine. I dont want you to put all this effort in, only then have it collapes on you.

[bighairyal]

I'm concerned about that as well - so was going to use lime instead of cement to bind the vermiculite. Or, as you say, some clay slip - if I find enough clay in my garden that is.

You probably are correct that cement based vermicrete will breathe based on it's open structure, but I'm not about to risk it!

[woodfiregourmet]

We did tests on Welsh quarry tiles in high heat (typical wfo temp)situation and they exploded dramatically so would not recommend. Am also not sure adhesion to firebricks will last. Your pizzas will come out much better on top of firebricks without the tiles. Sorry to be negative but feel it's better to share this info.

[bighairyal]

The issue of using tiles was at the back of my mind - but have seen a fair few other ovens using quarry tiles over bricks (the rather splendid barrel oven built by Calaf being a recent one) and have yet to hear of any explosions in actual cooking conditions.

That said, it could have happened (and been kept quiet) many times in the past......

Hence, you have my promise that if my oven explodes, there will be an admission, with photos to boot :-)

n.b. anyroad, I'm more concerned about those decking boards giving way once 300kg+ of bricks/clay & sand is finally sat on top of them ;D

[woodfiregourmet]

We tested in modified drum type BBQ and all was well until about 20 firings. Luckily for us lid was partially closed when large fragments came flying out at speed and only just missed us. Still believe in UK only options for floor are firebricks or refractory to get proper temp for crisp bottom pizza--in some areas of US soapstone is used but is too pricey here.

[bighairyal]

I shall consider myself forewarned. In the name of Health & Safety, perhaps I should don my diving helmet whilst firing my new oven?

[cannyfradock]

Al......I'm also still learning. Interesting comments and first-hand knowledge.

The pure nature of vermiculite will make it breathable, but after the comment from Surfing Spider, it may be better just to add another layer of clay or cob. With the addition of chicken wire, vermecrete takes well to lime render. I haven't read the books from Kiko Denzer....or Frankie G..or Alan Scott....perhaps I should. I have worked clay ovens on a few occasions 2 just with clay and one with vermecrete, but all 3 have seperate roofs...i.e no waterproof render.

I wish I had seen a post about you thinking of laying quarry tiles on top of fire-bricks......as it is I must agree woodfire-gourmet. The best possible hearth is Fire-brick hearth.....which you had!!!

I have been involved with 2 clay builds using "clay pavers" and after 18 months 1 paver has cracked but haven't heard of any spalling. Quarry tiles on the other hand are similar but quite different.....glazed finish' different composite....half the depth etc.

For joint filling on the hearth a lot of folks go for the natural ash to fill the fine joints as a fire-brick hearth is laid on refractory mortar, but dry butted. If the joints are more than a couple of mm's I would brush in a semi-dry mix of 1:1:1:1.......very fine sand, lime, cement and powdered fire-clay ......I used that on my last hearth and it has formed a crust and hardened nicely.



Terry

[bighairyal]

Well this oven is either going to work perfectly, or serve as a test case for a number of things that people shouldn't do in future!

If the tiles do go belly up once the dome is on top, it shouldn't be too much trouble to reach inside, remove them complete with firebricks, clean the bricks off, and replace. An unexpected benefit of making the oven fairly small :-)

I think I shall persevere with the lime/vermiculite layer + wooden roof option. I do believe it will be breathable - and besides, there is 200l of the stuff taking up valuable demijohn space in my shed.

Tally ho!

[minesamojito]

"Still believe in UK only options for floor are firebricks or refractory to get proper temp for crisp bottom pizza--in some areas of US soapstone is used but is too pricey here."

You missed off storage heater bricks!
I really think they're be hard to beat.
Cheers
Marcus

[Terry Hardwood]

All the reading I have done indicates that tiles should be perfectly fine. There are many examples of oven builds using tiles over firebrick so you should be fine. And they have been used in many old ovens in times gone by. One incident shouldn't tar the whole idea.

[woodfiregourmet]

Sorry--was including storage heater bricks as firebricks.
Also, be careful when ordering as some suppliers have sold insulating firebricks as firebricks.