Anyone used cob as material?

[benhunt]

Hi everyone. I'm new to the forum. I've joined because I'm getting married in August this year and I'd love to build a wood-fired pizza oven in our garden for the 3-day garden party we're planning.

I've watched Jonathan Townsend's video about building an 18th-Century-style cob oven, and wondered if there's any reason why this won't work for my project?

I've never worked with cement/concrete and so I'm drawn to the rustic and simple cob approach, which I'm guessing will be more likely to give me a good result.

Here's the video: https://www.youtube.com/watch?v=i0foHjPVbP4

The biggest difference I can see is that his oven, being designed to run at lower temperatures than a pizza oven, has no chimney in the "access tunnel". Q: Is the chimney essential for cooking pizza, and why?

Additionally, I'm not constrained by space, so I'd be interested to know what internal dimensions you guys would suggest as being ideal for a family? Will a bigger space take a lot longer to heat up, or does it just use a bigger fire? (Very newbie questions, I'm sure!)

Thanks in advance,
Ben

[cobblerdave]

Gday
A cob oven like shown is more than capable of exceeding the temps required for a pizza and burning them.
A chimney and entrance is s great way to keep the super hot gases out of your face and take them away safely over your head hieght. It can literally only take 1 sec to lose the front of your hair, your eyebrows and any facial hair. I recon a chimneys a must.
That is a small oven you could increase its size to 30 to 40 inches. Yes it will increase the wood required to operate. Time till heat up stay the same as a big oven has a bigger fire and a small oven can only have a small fire.
Regards Dave

[benhunt]

G'day Dave. Thanks for the feedback. I'll definitely incorporate a chimney then.

I assume the rule he mentioned of proportion to entrance/dome internal height should be about 63%, even if you've got a chimney?

[cobblerdave]

[QUOTE=benhunt;n387548]G'day Dave. Thanks for the feedback. I'll definitely incorporate a chimney then.
G'day
Yes that's right. Having an oven mouth at that ratio makes it breath correctly. The fresh air is drawn in low and exhurst leaves high. It works for diferent shape ovens mouths as well diferent shaped ovens. It's one of those things you just except works and try not to overthink it.
Regards dave