insulation with vermaculite UNDER Rocket ..?? I don't understand ..

I'm not THAT intelligent always.. So excuse me if for some people this situation is very obvious .. I can't get my head around it..
How can I insulate the Rocket with vermaculite while this huge mass of stone and brick is build on top of it..?  I attache an image in which I added a purple arrow.

Thanks for getting me out of the mist

Well, you can use a vermiculite bed which gonna squash under weight. With some type of gypsum boards or something alike, as a base layer for the bricks and all above. A guy from northern europe used clay balls. You can also use a big layer of insulating firebricks, air entrained concrete and such like. Plenty of options.

Tho, i don't know what will be your base. If concrete, you don't need an air gap. It doesn't matter much. But if wood. The only solution to avoid charring, is an air gap. With the stove fitted on rsj (ipn)  or something along those lines.

Thanks for your reply Satamax. We might have been in contact before .. Southern Alps on the french sit. Me in the french Pyrenees. Anyway. Sorry I'm dutch living in FR  dunno wot RSJ or IPN means .. Can you explain.
And yes it is on a wood floor. How would I create a gap ? By making stone "walls" close enough to one another ot pose bricks laying flat on top of those .. ?

Ok Petra, RSJ stand for rolled steel joist

https://www.google.fr/search?q=RSJ&hl=en&biw=1227&bih=620&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiHnqbsn5fPAhUCshQKHUBlDwAQ_AUIBigB#hl=en&tbm=isch&q=rolled+steel+joist

But you can also use scattered bricks. Pay attention to where the joists are, and fit the bricks on top of those. Then two layers of fermacel for example, and build the stove on top.

In your language there's a good rocket site.

Not that i can read it. But here it is.   http://www.ecologieforum.eu/

You know, you can use all sorts of things, and make all sorts of shape. Are you aware of the latest developpement on the batch rocket?

http://batchrocket.eu/

thanks. Very helpfull and great the batchrocket site, its new to me. Gonna dive into it strait away. Laterz