Cob: RE: RE: Insulation - vermiculite

[Sojourner]

Grace Benjamin wrote:
> 
> Hello All
> 
> 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.

No, you're thinking of perlite.  I presume you could use that for
insulation as well.

Vermiculite is super-heated mica.  It "explodes" into little vaguely
accordian-shaped bits.  It's a sort of shiny silver/goldish color.

I don't know how to describe it any better.  Hope that's good enough.

> 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?

Again, perlite could be used as cavity fill, or as you say above,
directly mixed into the cob.  I agree, it might affect the strength of
the cob.  As for anything you use as a cob additive it would behoove the
user to do some testing before relying on it.

Holly ;-D

> 
> Grace