Please help...Is our Stone Oven going to be OK?

[Benny78]

Hi guys,

So we have built a base out of regular house bricks standing 9 bricks high and 120cm length. There is a middle leg coming through as well.

On top of this we have four steel re-inforced concrete slabs, and a further cover of cement, roughly 2 inches deep.

We then have a base of fire bricks (cut in half) and fire clay cement. The dome is fire brick and fire clay and we are then rendering it with the fire clay cement.

Now......have we missed something to this point???? For example, when i was in bunnings the other day, their 'example' had an insulation blanket of some sort underneath the base of fire bricks. Ours does not. Is this nessesary? We have a fair sized area underneath the actual stove base for air to circulate.

Also, as for the dome, what do we NEED to use to insulate correctly? Are will it be OK with a couple of coats of render??

And finally, is it OK to simply build a chimney out of fire brick and fire clay??

Please help lads.....Cheers.

[Neil2]

"Ours does not. Is this nessesary?"

Yes.

[dmun]

Now......have we missed something to this point?

Yes. The insulation under the floor. Your are unlikely to get the oven up to pizza temperatures without insulation. You can either use two inches of refractory insulation board, or four inches of vermiculite concrete, between the support slab and the oven floor.

Also, as for the dome, what do we NEED to use to insulate correctly?

Again, two inches of refractory insulation blanket, or a minimum of four inches of vermiculite concrete.

will it be OK with a couple of coats of render??

Absolutely not. It will get too hot to get close to, and burn forests of wood without ever getting up to temperature.
Our motto here: insulate, insulate, insulate!

[lwood]

You need an insulating layer of perlite or vermiculite on both the underneath of the hearth firebrick and over the dome. If you don't you will be loosing a lot of heat and my not get to the proper temperatures.

[lwood]

Dmun, I guess we we responding at the same time, sorry for the repeat. But I guess it makes the point, eh.

[Benny78]

OK.....thanks lads. Insulation is being taken care of.

As for a chimney.....what's the best way to go about it? Can it be built simply with firebricks as long as it is a few bricks higher than the dome?

Or do i need to get a specific typy of pot? Or pipe?

[dmun]

Really any sort of chimney will do, or none. The main purpose of the chimney is to get the combustion gasses out of your face while you're cooking.

That said, most free-standing ovens have a chimney of two to four feet high. The taller, the better the draw, and the less likelyhood of soot staining the front over your door. flue tile is cheap, but to do it right, you should enclose it in something like brick. Stainless chimney systems are pricey, but insulated, and can safely be left exposed.

Like much else in oven building, there are many ways of doing things.

[Benny78]

Cheers for that.....

We are just going to use the remaining firebricks (maybe four high) to form a chimney and render it too (probably using a layer of insulation blanket under the render).

Hope that is ok?

[Benny78]

Here is a pic of the oven mate.

Does it look ok?