Dome/Hearth ratio

[mbutler315]

I want to build a pompeii style oven (I currently have an AS style that I built a few years ago). This will be a pizza only oven. I want it to heat quick and cook extremely well. Is it necessary for the hearth thickness to match the dome thickness? I want to use the FB pompeii plans. However, will 2" FB Board with a 2.5" thick firebrick hearth work well with a 4.5" thick dome covered in 2 or 3" of FB blanket? Or do I need to stand the bricks on edge to give a 4.5" hearth?
Thanks- Mark

[KINGRIUS]

Re: Dome/Hearth ratio

will 2" FB Board with a 2.5" thick firebrick hearth work well with a 4.5" thick dome covered in 2 or 3" of FB blanket? Or do I need to stand the bricks on edge to give a 4.5" hearth?
Thanks- Mark

You do not need to stand the bricks up on their edges. The FB plans call for laying the bricks down flat. If you use the 2" FB insulation board under the hearth bricks you will be very well insulated. 2 or 3" of insulation will be sufficient. But the moddo around here is "insulate! insulate! insulate!" so if you can afford any more insulation around the dome it won't hurt. But yes, 3" is plenty around your 4.5" thick dome.

Darius

[rbirchell]

Re: Dome/Hearth ratio

I agree on the floor; lay the bricks flat. The 2 inches of insulation board is more than adequate. One area of deviation is the thickness of the dome. If just for pizza's then a 2.5 inch thick dome would work fine too. Note the geodesic design for example. The thinner design will heat up faster (significant?) but hold less heat for extended baking. I went with the 4.5 for more mass and dome stability. Note my opinion is to be taken without any expertise behind it. I built an oven. But, that is where it ends.

I ordered 2 boxes of insulation blanket and doubled up on my 36 inch dome. I liked that route as opposed to all the bags of vermiculite it would have required. I think the 2 boxes gave me about 5-6 inches over most of the dome. I ran it up the sides of the arch and chinmey also. Enclosing the oven versus an igloo finish will play a role though. I did the enclosure and wasn't too precise with fitting the blanket. The first layer is snug and the rest flopped on.

The 16 inch dome cooks pizza's very nicely. But, I would have to experiment with a taller dome to compare the behavior differences. So many variables come in to play when making what I consider the perfect pizza. That is the art aspect.

Enjoy your build.