Vermiculite Questions

[lhuhn]

I finally located vermiculite in the garden section of Lowe's. Is this the same product as what is used in the oven construction? I read somewhere that the correct ratio is 5:1 but nothing more. I assume this is 5 parts vermiculite to one part portland cement by volume. Is this correct?

[GianniFocaccia]

Correct. I have seen builds here on the FB site that utilized ratios from 5:1 to 12:1. Understand that the higher the percentage of portland cement,the stiffer the mix will be and the lower the insulation value and vice versa. I went with 8:1, right in the middle. I made a slurry of the cement in water and added it to the vermiculite in a wheelbarrow and added just enough water for it to become (gently) combined, or in cook's terms, incorporated.

[RTflorida]

Yes, garden variety vermiculite is what you want. You may want to try calling any local growers or landscape suppliers. The Lowes around me only sell the small bags at a pretty steep price. The plant growers usually have the large 4 cu. ft bags for $18-$30.
5:1 ratio is recommended for the under hearth insulation. If using the same for the dome, you can stretch it to 8:1 or even 10:1. Yes this is the ration of vermiculite to p cement
RT

[eatingmorefood]

Hi All,
I'm busy cooking and eating, all the time, but finally I am Builiding my first oven, likely a 36 in. ID Pompeii style!
Wondering how thick my support slad should be ? Hearth is 48 x 48 in. and plan to use 10 pieces of 1/2 rebar in slab. Then a second slab of vermiculite - concrete mixture on top of the slab. Is this correct so far ?
thank you !
Chef

[fxpose]

Originally Posted by eatingmorefood

Hearth is 48 x 48 in.

You should go a little bigger than that for a 36" oven.

[eatingmorefood]

Fxpose,
How big should my Pompeii oven be if My hearth plan is 48 in x 48 in ?
Would you think I am crazy to build it next to my WOOD DECK ?
What are the chances of sparks jumping out ?
Thanks!
EatingMoreFood

[dmun]

George is right: 36+9+8 = 53, not counting cladding or enclosure, and you'll need more for the entry side unless you're planning a corner opening.

[eatingmorefood]

Hi Dmun,
Your oven is amazing. Thanks for the reply, maybe it will be 32 inch ID ....
Wondering how thick my support slad should be ? Top of concrete blocks stands at 48 x 48 in. ( I could pour slightly larger) plan to use 10 pieces of 1/2 rebar in support layer of the slab. Then a second slab of vermiculite - concrete mixture on top of the slab. Is this correct so far ? Plan to use my large supply of 14 in x 16 in. x 1 in. pizza stones (cutting them up).
Would you think I am crazy putting this oven 1 foot from my wood deck ? I want to be able to cook off the high deck. The oven will have a door, of course. Do many sparks pop out the front of your oven?
thank you !
EatingMorefood - Chef