What to use as cooking surface?

[charbob]

Getting ready to build a clay wood fired pizza oven, and I'm stuck on the cooking surface. Fire bricks are extremely expensive, so I've been looking into alternatives/homemade options. I'm a little confused though: it seems like there are two types of fire bricks but the term is used interchangeably. Unless I'm just missing something! One type is for insulation and the other (refractory?) holds heat for cooking. Or again, maybe I'm just confused and they're both the same.

I found a recipe for refractory cement that uses Portland cement, perlite, silica sand, and fireclay, but no information on whether it's safe to use as a cooking surface. I'm kinda thinking that refractory cement isn't the same as what fire bricks are made from; I get the impression that it's used as the form for the oven, not as the bottom.... thoughts?

Another recipe for homemade fire bricks uses just fireclay and perlite, and these "look" like the right ones, but I don't know if I'm supposed to be using a different type of brick (this is where the confusion about refractory bricks comes in!). Are all fire bricks the same or is there a difference? Can I use the clay and perlite mix to make fire bricks as the bottom/cooking surface of my oven? Or do I need something that has actual cement and/or sand in it?

If I use these homemade fire bricks on the bottom of the oven, do I still need something underneath the fire bricks as insulation? I'm building the base out of cinder blocks and wood.

I think that's all the pressing questions I have for now. If someone has made fire bricks successfully, please direct me to their information! Most of what I have seen have been used in forges or to build the oven dome, not the bottom. Thanks, everyone!!

[UtahBeehiver]

I am going to suggest you download the eplans from Forno Bravo, they have a good brick primer in the appendix as well as good overview of materials and building processes. Although somewhat dated it is a good baseline. The cost is 2-3 bucks. What do you define as extremely expensive for bricks, most new bricks can be found under $2 each and with a little time and searching, surplus bricks under $1. Since you doing a clay oven you are only talking the floor. If you want your oven to perform well you will need insulation under the floor and well as over the dome. All of this is covered in the eplans.

[Gulf]

What price range for fire brick are you seeing in Missouri?

[charbob]

Cheapest I can find is nearly $5/ea. That's way too high. I can make them (if either of the above referenced recipes would work) for less than $0.50/ea.

Yes, all I need information on right now is the bottom; thanks for clarifying the insulation question for underneath the fire bricks/cooking surface!

[charbob]

The local places I'm seeing sell multi packs that average $5-7 each. Even if I build the oven out of clay and only use fire bricks for the bottom, that's still WAY out of the budget!

The local clay supply store suggested using a kiln shelf as the cooking surface; has anyone done this? I would rather use fire bricks because they would be cheaper if I can make them myself and more easily replaced.

[charbob]

My replies aren't showing up for some reason...

[charbob]

Never mind, there's just a delay between posting and them showing up. So are all fire bricks the same? Or is there a difference between types?

[Gulf]

It sounds like you are pricing at "fire place" stores. Many of them are way overpriced. Look for a brick/masonry yard or local building supply in your area. You need to buy where the contractors are buying. their materials.

[charbob]

So can anyone she'd some light on the homemade versions I posted? And especially on whether there's a difference between types of firebrick? I'll see if I can find a masonry supply, but just in case, I would like to know if the homemade versions could work. Thanks!!!

[Gulf]

Both of the recipes you listed above are for an insulating refractory. Neither are good for a cooking surface.

[charbob]

So there is a difference between fire bricks and refractory bricks?

[Gulf]

The fire brick that we need for a cooking surface and the dome are a refractory brick. But, they are a dense refractory that is harder.and will hold the heat. The formulas that you listed are for less dense, softer, insulating refractory material.

[Jerry Sumrall]

Wouldn't it be better to use some type of flat stone for the cooking surface?

[Johnnyd943]

Essentially, a refractory fire brick is a flat stone...man-made ( MMFS) Using many of these MMFSs on the oven floor allows for the expansion/contraction of each individual stone...Therefore, much less likely to crack.