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GianniFocaccia 04-09-2010 10:06 PM

Soapstone Hearth
Now that my outdoor kitchen patio and walkways are almost finished I am very close to starting work on my actual oven! I came across a local ad for a guy selling a 36x36" soapstone slab for $90. It is 1 1/2" thick.

What is the practicality of placing this in the center of my 42" oven and surrounding it with the 2.5" firebrick that I'll be building the rest of the dome with? I understand normal fire placement is on the perimeter of an oven, and that I will have to build up an inch of oven floor under the soapstone.

The two questions I have are: Should I build the 1" soapstone 'base' out of fireclay/sand or 1" firebrick splits? Would a soapstone/firebrick oven floor heat evenly enough to be worth the added cost?



lwalper 04-19-2010 01:15 AM

Re: Soapstone Hearth
Soapstone is a great heatsink. I forget the math, but that sounds like a perfect hearth combination. Go for it!

SCChris 04-19-2010 11:42 AM

Re: Soapstone Hearth
The thickness of the stone is likley 3cm or 1.2 inches so you'll have a bit of work to get the level of the 2.25 inch thick firebrick and soapstone to match. You may find that the same place has a few leftovers to fill in the gaps. The other way to handle it would be to put the 1/2 thick bricks around the stone. I think they call these veneer bricks. I'll bet you can find the SStone leftovers. If I were going to put a SStone floor in my oven I think I'd consider putting in another inch of rigid insulation.


dmun 04-19-2010 12:38 PM

Re: Soapstone Hearth
Soapstone makes a great floor. Is it worth the cost? That's your call. Firebrick works fine.

Here's a link to a mha project: an oven with a soapstone floor.

GianniFocaccia 04-20-2010 09:27 AM

Re: Soapstone Hearth
Thanks Dmun. Excellent example of a 'partial' soapstone floor. A local stone yard says it has relatively inexpensive remnants that I think could be cut to fit inside my dome. They may not match but I'm not picky. Obviously, the fewer seams, the better.

Because soapstone reportedly heats up quickly, I'm thinking of laying it right on top of my firebrick floor instead of directly on my insulation (2" of Insblok on top of 3 1/2" of vermicrete). Would a 4" thick floor require a significant increase in wood to heat up?

SCChris 04-20-2010 10:14 AM

Re: Soapstone Hearth
I don't know what to tell you on the additional heatup time, it will take more time to heat more mass. I know that the SStone that I have is heavy. If I had to guess it would be that SStone is about twice the weight per volume relative to firebrick.

I don't know and can't guess how SStone cooks relative to brick. SStone is non-porous where brick is highly porous so cooking directly on these surfaces has got have some differences.

I'm very happy with the SStone entry surface it's easy to keep clean and to slide things in and out. The brick works great as well and in this inner oven area it is "self cleaning". I would also say that pushing things around within the oven isn't a problem with the brick but things would slide easier on the SStone.

Keep us posted on where you go with the SStone.


GianniFocaccia 04-20-2010 01:41 PM

Re: Soapstone Hearth
Thanks for the info, Chris. The soapstone looked attractive because of its smooth surface, much more accommodating than the rough (wirecut?) Pacific Clay firebricks I bought.

It will all come down to the cost I can get for the pieces.

edsalldw 05-25-2011 12:10 PM

Re: Soapstone Hearth
Hey Gianni,
Did you ever go ahead withthe soapstone/ Did it work well? Do you make bread with it?
I am about to build a 27" oven and can do the whole floor in one piece of soapstone. BU tsince it transfers heat 4 tiems as fast as brick Does it run the bottom of teh laoves. like brad buildrs says. But no one has yet said " I do it and it does burn - or does not burn."


GianniFocaccia 05-25-2011 06:50 PM

Re: Soapstone Hearth

Good questions, all. Yes, I did go ahead with the soapstone but haven't completed the oven yet so I can't comment on the effectiveness of cooking bread on it. Some random thoughts that might affect the construction of your oven with a SS floor:

1) try not to use a single piece of SS. If it ever needs to be replaced (it is very soft) a single piece would be impossible to remove. If you look at my thread OctoForno, you'll see what I did.
2) try to augment the amount of underfloor insulation if you go with soapstone on top of firebrick like I did. I have a total of 5 1/2" of vermicrete and ceramic board under the floor.
3) I have been told that once the floor has equalized down to the proper bread-making temperature it should work fine.

I am ecstatic that I was able to secure the soapstone in the dimensions I did at the relatively inexpensive price I paid: $200. I wanted to try a non-traditional floor and be able to report back on the relative merits of this kind of floor and whether it is worth it or not. The fact that east coast builders can reportedly get soapstone even cheaper makes me jealous. I feel a 27" pizza oven with a soapstone floor is a definite winner.

lwood 05-27-2011 10:02 PM

Re: Soapstone Hearth
Hi John,
I'm interested in how the soapstone performs. Soapstone has a higher thermal conductivity than firebrick but about the same heat capacity. Given that, it should give you a better oven pop than firebrick. Or lighter, fluffier crumb. Does it brown the bottom faster, don't know(that would not really be a good thing). Will be interested in your comments after you have used it a while. I am planning soapstone on my next oven.

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