Red clay roof tiles fire resistance?

Hi everybody.

Well, i would like to use a type of corbel vault whhich is used in france usualy with dry stones.

To build a wood fired oven. Does anybody here has the slightest idea on the fire resistance of red clay roof tiles? I'm planing to find a bunch of thoses, secondhand.


Something like thoses. To make domes like theses. http://www.pierreseche.com/cabanes_detoiturees.htm

Roof tiles usually have been considered to have a one hour fire rating, meaning if they are on wood directly the wood "shouldn't" ignite within 45min to 1hour, but I am not sure of the resistance to structural failure under repeated heating use....

Thanks a lot Chadwick.

If ever i bump onto some around here (i live too high for tiles, here's slates, roofing stones, steel or wooden shingles land) I will fire aa few in another rocket, to see what they cope with.

I used red clay roof tiles for ducts in my rocket stove-- but that wasn't extreme heat. AFAIK, they are the same sort of clay as red bricks. Of course, not as thick, and if they are like those in Slovakia, they have hollow chambers in the inside (I guess to reduce weight).

But where will you be putting the tiles? On the outside like a roof?

Andrew, i was thinking of making it like the dry stones huts showed in the link. That would be inside of the vault at one end of the tile, and outside of the vault at the other end. Fitted with cob in between. They would serve as a "mineral charge" kind of. I mean, a wood fired oven can be made of only cob. But you have to hold the vault somehow during the building process. And then after, you have to protect it. In this case, it would be self protected. And self holding. Which would be intresting.

Well, i've never seen hollow roof tiles in my life. Never ever. But i can tell you, thoses are not hollow. They are usualy old. There's still some factories making thoses. But now adays, they tend to be more formed. Than flat tiles.

You're wanting to build a cooking oven with them right? They'll stand those temperatures easily but the cob between them will shrink but the tiles won't, which might cause problems.
I think the 'need' for support while building arches is grossly exaggerated in the 'west'. There are thousands of domes and arches in the middle east that were made without support, and some of them are huge. For some reason western builders don't believe that they were built without support and insist that everything be supported. Which is probably not a bad thing for 'health and safety' on large structures, but small stuff really doesn't need it, especially when using cob. Any half taught pottery student can build a pretty decent coil pot with normal clay, and cob is even easier to build with.

I've managed to find a couple of videos that show the possibilities:
These are amazing and a lot thinner than I've seen 'irl'. If you do try building this way, be aware that each layer has dried and stiffened a bit before the next layer is added. (just a bit, nowhere near completely dry, still soft enough to blend with the next layer)


This one uses cob and is completely different from what I was expecting, but still gives a lot of ideas.


The one I saw being made was a lot bigger and made like a coil pot, the finished item being a cross between the two types, and set into the ground rather than a barrel.

Friends have recently built an oven using sand as a former, and had problems with cracks. I strongly suspect that this was due to the sand former preventing the clay from shrinking normally, like a pot would!

Thanks a lot Marion for the reply.

The portuguese oven ressembles quite a bit the "chiminea" https://www.google.fr/search?q=chiminea&rlz=1T4SAVJ_enFR550FR551&prmd=ivns&tbm=isch&tbo=u&source=univ&sa=X&ved=0CCAQsARqFQoTCPSs0urVrcgCFYJUGgod9eYDHg

Don't know if they're built the same. But there's a link somewhere.

Well, the tile oven thing is also to see if i could do that type of colbel dome. I realy would like to make a dry stone one once in my life. There's several interests comming into one in this idea.