advice on cladding masonry dome

[afrompa]

Hi all - I've completed my masonry oven dome, and I'm at the point of cladding it. The dome is regular brick with homemade refractory mortar of fireclay, sand and portland cement. I've mostly used Wing/Scott The Bread Builders for design and materials guidance, but I find myself without adequate guidance on what to use to clad the dome. Do I use a mix of vermiculite/Portland cement/fire clay or portland cement/lime/sand? Any advice, I'd appreciate. I'm in a location where we get as cold as a few degrees below zero farenheit in winter, as warm as low hundreds in summer. The whole thing will be enclosed by brick, when completed. Thanks in advance for your help.

[afrompa]

I guess I spoke English in a French speaking country. Sorry for the faux pas.

[Tscarborough]

You can use perl-crete, but loose fill insulation in the house will be even better.

[Ken524]

I wouldn't add more mortar to the outside. You don't need the thermal mass. You want insulation, and lots of it.

The very best thing would be 3"-4" of refractory blanket. If that isn't an option, you'll also get great results with the mixture of vermiculite and portland cement (4" or more). Don't add fireclay to the vermiculite/portland. Fireclay is thermal mass, not an insulator.

You might want to download the free Pompeii oven plans. They will give you lots of detail for your next steps:
Brick Oven Plans | Build an Italian Brick Oven

[david s]

Originally Posted by Ken524

Don't add fireclay to the vermiculite/portland. Fireclay is thermal mass, not an insulator.
]

Portland is not a good insulator either. Even at 10;1 you are adding more mass to the mix from the cement than the vermiculite.

[Ken524]

Originally Posted by david s

Portland is not a good insulator either.

I agree! Even more reason not to make things worse with fireclay