Concrete vent, flat entry

[Poetryart]

Okay, Christmas is over, so it's time to get back to work. I had everything planned out as to how I was going to create the arched entry, etc., but being "of a certain age" has led to trying hard to remember my plans. Instead of a graceful arch, how about a flat entry, with a graceful decorative arch only where you'd see it? and then, how about a cast concrete vent? The question I have for ya'll is: does the concrete need to be the mix of perlite or vermiculite or can it be ordinary ol' concrete? I still plan to sculpt a really cool something to fit over the whole thing, but that won't be ready for months. Once the entry's decided, or done even, then I can finish the dome. ...and the insulation..and the stucco...and...and... when will I ever get to make the pizza?...sigh.
Thanks! - Shelley

[brickie in oz]

Any thing with portland cement in it wont take the heat of an oven, concrete included.
You can buy refractory concrete that will withstand the heat though.

[jab49]

Hmm, the plans just call for standard concrete, if I'm not mistaken. One would think the vent wouldn't be taking anything like the heat present inside the oven. However, the plans also don't mention that a thermal break might be a good idea. I see others have built thermal breaks before or after the vent. As I'm following the plans directly, perhaps the plan author could advise us on this?

[david s]

I think the FB plans call for a brick entry. However there is no reason you can't cast one, in fact there are great advantages in casting it because it is easier to create funneling to the flue pipe, it is also easier to create a shallow entry for easier oven operation. Don't use standard concrete though, as others have advised, use a castable refractory.

[Amac]

Instead of a graceful arch, how about a flat entry

Do you mean an entry with an angle - iron lintel? I found the semicircular arch to be the easiest solution in theory and - since I have just finished the dome arch transition - also I am more than happy with the outcome. The thought of contaminating the dome with angle iron just didn't appeal.
http://www.fornobravo.com/forum/8/39...tml#post127957 (39" Stargate Pompeii)
Aidan