Pour / Casting the Oven Floor

[JamesLynn]

Hi All, My very first post. Just about to start contruction of my new oven. Base is done, now running around sourcing bricks, etc and trying to decide vermiculite or FB board base etc. Fortunately for me there's a wealth of excellent information in these forums!

In my research I've come across lots of information on refactory products and I'm wondering why no one has tried to pour a oven floor rather than use fire bricks. There seems to be many castable/refactory concretes available yet I've never seen any posts asking this question or seen it done.

I figure there's probably a very good reason why.

I'd be interested if any one has thought the same and has any guidance on this?

James

[nissanneill]

Re: Pour / Casting the Oven Floor

Hi James and welcome aboard,
to answer your question, I have to make some assumptions, which is not necessarily all that wise as we all know what happens when one assumes! (makes an 'ass' out of 'u' and 'me').
Well here goes.
? Why become an explorer and play with the unknown in casting a one piece very hot surface which would need reinforcement to reduce or prevent cracking?
? Cost? To purchase a castable refractory material when we already know that bricks work fine and have done for centuries!
? Timeline! laying bricks and cutting the perimeter bricks is all over and done in a couple of hours.

I for one would not use castables for cost and the unknown. Technology is a wonderful thing, BUT I will always go with a known (and safer option) rather than an unknown.

Neill

[Frances]

Re: Pour / Casting the Oven Floor

I think the main reason no one has asked that before, is that it is really easy to lay the floor, far easier and quicker (and cheaper?) than building forms for casting, then waiting for it to cure before getting to the dome.

The brick floor pattern looks nice too. But I don't see why it shouldn't work - the premade oven kits have a cast floor, don't they? But then you'd have to work out reinforcing...

[james]

Re: Pour / Casting the Oven Floor

The castable that offers the same refractory qualities as a firebrick cooking floor is very specialized and it very difficult to work with. It's easy to get it wrong and have the casting not come out correctly.

Firebrick is a safe and reliable method -- and it works really well.
James

[berryst]

Re: Pour / Casting the Oven Floor

I think cast able should work beautifully. It's not going to require much reinforcement as it sits on a flat surface. So long as there is room for expansion it should work. My guess is that you want to achieve a really flat smooth surface. I was concerned that brick would be too rough for pizza but my concerns were for not. The brick lays smooth and works beautifully for pizza. It's tried and true. If your going to try pancakes that may be a different matter altogether
berryst

[james]

Re: Pour / Casting the Oven Floor

Berryst,

I think you put your finger on it. It should work beautifully -- but the devil is in the details. :-)
James

[JamesLynn]

Re: Pour / Casting the Oven Floor

Thanks All, Decision made. Sticking with the tried and tested bricks! After I posted the question I read the technical details on using the castable concrete. Very fussy stuff as far as mixture and temperture goes. James' point about getting it wrong was spot on. It looks like one of those products that requires experience and lots of! Once again appreciate the feedback.
Regards
James

[Johnny the oven man]

Re: Pour / Casting the Oven Floor

Castable is great if its fired, but needs to get to 1000c to get the ceramic bond. In a WFO it would stay very"chalky". The hardest setting castable would be the low cement varieties.

[james]

Re: Pour / Casting the Oven Floor

I don't think that is always true. There are castables that set through a chemical reaction without firing. As JamesLynn says, they are fussy about the exact mix of castable to water, setting temperature, mixing time, etc., but they are not fired.

I guess it's a modern alchemy. We're making pizza (not just gold) from base metals. :-)

James

[JamesLynn]

Re: Pour / Casting the Oven Floor

It's a small small world. Today I ventured out to a local refactory supplier to pick up some supplies. The person assisting me was extremely helpful and knowledgable about WFO's. During our discussions the subject turn to the topic of casting an oven floor. He mentioned he had replied to the same question that morning. It turns out I was talking to "Johnny the oven man" himself! What are the chances of running into the person who responded to your question on the same day?

[asudavew]

Re: Pour / Casting the Oven Floor

It's a small small world. Today I ventured out to a local refactory supplier to pick up some supplies. The person assisting me was extremely helpful and knowledgable about WFO's. During our discussions the subject turn to the topic of casting an oven floor. He mentioned he had replied to the same question that morning. It turns out I was talking to "Johnny the oven man" himself! What are the chances of running into the person who responded to your question on the same day?

Now that's funny! And quite odd. Are you sure that you aren't stalking johnny?



Don't forget pictures of your build! We like pics!


Dave

[james]

Re: Pour / Casting the Oven Floor

How cool is that. We're pizza oven central -- you can't get away from us.
James

[andrew doeven]

Re: Pour / Casting the Oven Floor

Hi there James, I'm about to use a styrofoam insulation base [as in heavy duty cool room panel 4 inches thick ] and pour a concrete slab on top 3 '' thick ,then 3 '' of fire brick and then a beautiful fire slab on top of that. what do you think Cheers andrew. The oven will be 36'' x 48'' as in igloo dome. cheers again

[dmun]

Re: Pour / Casting the Oven Floor

If you're putting the brick floor down anyway, why cover it up with ugly refractory? As another poster said, you're not making pancakes on the floor.

And offhand, it sounds like you have too much thermal mass on top of your insulation, even without the refractory slab on top.

[RTflorida]

Re: Pour / Casting the Oven Floor

Andrew, I think you are going to need an endless supply of free wood. You are putting your insulation under 6" of slab/firebrick and a fire slab (not familiar with this), I'm guessing at least a 7"-8" thick mass to heat up each time - a huge mass for a non-commercial bread oven....Very difficult to reach and maintain pizza temps, although it would work well for extended bread bakes.
Your insulation needs to be under the cooking surface if you want to do pizza well...As a compromise (decent pizza and multiple bread bakes) you could probably go with up to 4" of mass, then the insulation. This would still require several hours to heat up.
I would seriously consider building from the Pompeii oven plans available here (free at the Forno Bravo store). This is a great compromise for multipurpose use.

I'm also questioning you insulation choice...anything styrofoam is not suitable for the high temps associated with a wood fired oven...it will melt. Again, check out the available plans and read, read, read, the many informative threads on this site...there is a wealth of information here that has been proven to work.

RT