Natural stone vs firebrick for thermal mass

[PerryPizza]

Has anybody used natural stone instead of refractory bricks to build the dome? The old local bread ovens are all constructed using local stone, and I have a huge amount of it just sitting around waiting for a use. If the thermal mass properties are similar I might give it a go... but I'll wait to hear the forum's views of course

[PIZZAMANMIKE]

Re: Natural stone vs firebrick for thermal mass

I Would Give It A Try, If It Works Great ,if Not, It's Just Some Time And A Few $'s And You Can Use Them On Something Else. At Least Your Deck Will Be Done And The Second Time Around You Should Save Some Time On Your Dome.

[dmun]

Re: Natural stone vs firebrick for thermal mass

Lots of traditional ovens were built with stone, but make sure it's not a sedimentary stone like slate that's going to flake off in heat. Any hard stone should work fine. Don't go overboard with the traditional construction and try to skip the insulation top or bottom: That's a must.

[nissanneill]

Re: Natural stone vs firebrick for thermal mass

dmun,
you have me a little confused:

Don't go overboard with the traditional construction and try to skip the insulation top or bottom: That's a must.

Why would one recommend not to insulate unless they live in a forest of dead trees with someone keen to cut them up?

Neill

[dmun]

Re: Natural stone vs firebrick for thermal mass

Why would one recommend not to insulate unless they live in a forest of dead trees with someone keen to cut them up?

There are a bunch of traditional oven sites that recommend insulating with useless stuff like sand, gravel, or broken glass. If they come here with odd ideas about construction materials, they may have absorbed the no-insulate "lesson" as well.

A word to the wise: Insulate! Insulate! Insulate!

[PerryPizza]

Re: Natural stone vs firebrick for thermal mass

Don't worry, I've done my homework & think I've got a reasonable grasp of the principals of brick oven dynamics.

I love the idea of using the local stone instead of refractory brick though, it just seems more in keeping with the house I live in. I also prefer working with irregular shapes which seems crazy to some of my fellow builders, but I get more satisfaction during and after the construction, it brings out the hippie in me. Not sure I'll be saying that once I get stuck in though! But when it comes to insulation modern methods & materials come into their own..... unless anyone has had success with duck-down, which is also abundant locally!

[Frances]

Re: Natural stone vs firebrick for thermal mass

I love the idea of using the local stone instead of refractory brick though, it just seems more in keeping with the house I live in. I also prefer working with irregular shapes

I can't wait to see this, sounds great! Please make sure to take lots of pictures and tell us how it works out (or not as the case may be... ), I'm sure there'll be builders who will want to follow in your footsteps.

[Wiley]

Re: Natural stone vs firebrick for thermal mass

Pizza Perry, So what is the local stone?
Wiley

[PerryPizza]

Re: Natural stone vs firebrick for thermal mass

Good question, I'm no geologist but would like to find out. I live in the Dordogne region of France (Perigord Noir). Here are some images of the village, maybe someone can help?

Sainte-Orse village de Dordogne dans le P?rigord

Whilst looking I found an old barn for sale in Ste Orse with a bread oven (which doesn't look like it's been used for a while!)...

[Wiley]

Re: Natural stone vs firebrick for thermal mass

Ahhh, The Dordogne, a very beautiful region and one selected by prehistoric man to live because not only did it have a temperate climate at the end of the last ice age but because it had wonderful caves. Lascaux, Les Eyzies de Tayac... Grotte de font de Gaume... been there done that :-)

The regional rock is limestone and here's a link to quicklime:
Calcium oxide - Wikipedia, the free encyclopedia

Which you will no doubt find interesting. 825 C is hot even by our WFO standards. I would think it would work but I would also think that making sure that it is weather tight as limestone is usually porous and any leak would allow water to infiltrate the stone itself which might result in problems with spalling from the water turning to steam and poping off the surface and perhaps deeper than the surface.

Lucky you, the Dordogne Valley is very beautiful!

Wiley

[Wiley]

Re: Natural stone vs firebrick for thermal mass

A second look at the photo you attached.... the arch over the entrance is made with Roman bricks. I wonder how old the oven is and whether it was made with recycled materials at the time of it's construction or perhaps actually dates to a time the Romans occupied the region.
Wiley

[PerryPizza]

Re: Natural stone vs firebrick for thermal mass

I took down a partition in my house which was made with the same terracotta bricks & I have a pile of those too, which I was also considering using in the oven construction. The Romans were certainly here, I live next to a Roman church, though I've always imagined the bricks were made more recently. Having said that, the buildings are made with anything going - I have a round column laid horizontally in one of my walls - I have no idea what that was used for before. There's no telling how much recycling has gone on over the centuries, and will continue with me!