Cob Fibrous Cement & How To Join ESSA/ earthship listserv (reply)

[Don Stephens]

Craig,

I agree, I'd love to see some hard, reliable test data!  If this stuff is
basicly wood fiber, sand, cement and, once it drys, some air where the
water was, then one might expect practically no R-value from the cement,
sand or dirt and about i i/2 per inch for the wood fiber.  Add a little
air and it might creap up toward 2, but I'd doubt it gets above that.
Still it might just be a good "brown-coat" for low-R stuff like cob in
colder climates - put up the cob with short sticks projecting to tie into
the F/C stucco, slap on several layers of F/C to build up 8" - 10" of it
and then finish stucco, for a wall with a high mass, an R-value of ~ 20,
and 0 infiltration! I wonder.... Don

On Sat, 20 Jun 1998, Craig Hull wrote:

> 
> 
> > Fibrous cement is amazing stuff.  Mike makes adobe like blocks from it
> > and uses it like adobe blocks.  Properly mixed fibrous cement has a load
> > bearing strength greater than adobe, and is lighter than adobe and has
> > an R value of 2.8 per inch.  That means a 1' wall has a value of about
> > 33+ R value a 2' wall would be 66.7. It will hold a screw, you can build
> > the structure then cut the doors and windows with a chainsaw.  Mike
> > builds the walls and roof from this material.   Fibrous cement will not
> > burn and termites will not eat it. You can paint it, use it like
> > plaster, seal it with hot tar or cover it with elastometeric plastic
> > coatings.  It is easier to work with than regular cement since it is
> > lighter and too much water simply drains away instead of weakening the
> > mixture.   It is not satisfactory for footings or situations where it is
> > subject to high continuous moisture saturation.  Mike does construct
> > buried structures.
> 
> Does anyone have any test data on this stuff. The above description sounds
> too good to be true. Especially the R2.8 per inch. Would this make a good
> plaster for straw bales, with or without the claimed R values?
> 
> 
>