Cob: RE: Insulation - vermiculite

[Kelly, Sean]

Grace and Holly, 

thanks for the info (you learn something new everyday!)  That stuff is like
some sort of air popped rock, right (not really styrofoam)?  I didn't know
the name, but the description nailed it for me.  I would kind of (maybe
not... it IS very small...) wonder what it would do in the mix of cob.  What
about this?  A full cob wall 2-3' thick - straight cob.  Add a 6" layer of
vermiculite laden cob to the outside as a very thick outer coat?  or even a
foot if you like...  the straight cob would be the mass of the wall, so
would do most of the load bearing, the outer coat like a plaster coat, so if
it comes off, you can just put more on...  I guess insulative value would be
proportional to how much vermiculite you add to the mix, but what about the
idea?

-----Original Message-----
>From: Grace Benjamin [mailto:grey_sea at hotmail.com]

>Vermiculite is the fluffy, white, lightweight material often found in 
>commercial potting mixes.  You can buy it seperately, and it has the 
>texture and consistency of polystyrene (styrofoam) "popcorn" just 
>much, much smaller pieces.  I assume Lyle's intent is to incorporate it 
>evenly into the cob mix, just like it is mixed into potting soil- and for 
>very much the same reason- to keep air spaces in the mix.

>While a terrific idea, my only concern is denigrating the stability of the 
>wall as a whole; has anyone tried this?

>Grace