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It could be done but you get a more even heat distribution if you stay with the dome design. The opening may be rectangular. The arches we are employing today are for more of an aesthetic purpose. The first builds were square.
A couple of years ago I was asked to put together a modular kit oven that was of this configuration. They were cast panels that interlocked. It was quite a clever design and I was told it performs ok, although its insulation was inadequate.sorry, I can't remember the name. The front and back panels were vertical while the sides were angled in and the roof sat horizontally on top. All the panels were designed to interlock.
A dome may be considered a series of arches rotating around a vertical axis, with gravity holding all the bricks together in compression, and is therefore very strong.
A flat ceiling would need to be a one piece cast item as per Dave's anecdote. If it was made of bricks mortared together, the forces of gravity would not hold the bricks together in compression. You couldn't make it from brick, or it would fall in.
Also I believe the arches used for openings today are for more than aesthetic reasons. Done correctly, the arch marries into the dome shape better than a rectangular opening and will not require any additional buttressing or lintels.
A rectangular opening with a flat ceiling will need a lintel to stop the bricks falling in (see brickies question - what holds it up applies to openings too). A rectangular opening with a shallow curved ceiling may required buttressing to stop the shallow curve pushing the vertical walls out.
Thats what I said........
The English language was invented by people who couldnt spell.
"A flat ceiling would need to be a one piece cast item as per Dave's anecdote. If it was made of bricks mortared together, the forces of gravity would not hold the bricks together in compression. You couldn't make it from brick, or it would fall in."
That's not exactly true. While mortar won't hold together a flat roof made of bricks, there is another way to do it. I built a kiln many years ago with a flat brick roof. I didn't invent the idea, but the bricks were held together unmortared with threaded steel rods through their centres and placed over the kiln in sections (5 bricks at a time from memory) many other kiln builders have used the same technique. I used dense firebricks, but it can also be done with insulating firebricks or solid reds for that matter. Someone might like to experiment with this idea for a WFO.
Last edited by david s; 09-14-2012, 04:19 PM.