Cob: RE: Better than a cob "sandwich"

[Chuck & Linda]

-----Original Message-----
From:	Majordomo [mailto:majordom at deatech.com] On Behalf Of Bob
Sent:	Friday, August 25, 2000 2:15 AM
To:	coblist at deatech.com
Subject:	Cob: Better than a cob "sandwich"

Thanks for all the improvements on my suggestion of sandwiched straw.
Bob,

I second Sarah's vote for Strawbale. I live in Wisconsin and unless you want
to be chopping wood day and night, find a way to use straw.  If you build
with a good foundation so that bales are well off the ground and ideally
wrap porches around your north, east and west sides, then snow and rain will
be far away. I have built things with Cob and Strawbales and the two
together. Two inches of cob plaster is more than enough thermal mass, add an
earthen floor and your all set.
There is no reason for straw to decay, it requires a very high percentage of
moisture to achieve this. Nobody in Wisconsin is experiencing decay.

Earth when it is dry will hold  somewhere between 2-5% moisture depending on
who you talk to. Straw averages around 8-12% thus the earthen plaster
assuming there are not intense vapor barriors to interfere will wick the
moisture out of the straw, thus ensuring the health of the straw.

My house will have those porches everywhere except the south with earthen
plasters inside and out. The only place I will have vapor barriers is in the
bathroom.
If you have a woodstove internal moisture is not a problem.  If you are bent
on this double cob wall, then I would think that straw would be a good
insulator or recycled packing peanuts.

Chuck



I understand one of the problems with straw bales is they settle more and
longer than cob.  In our area straw bale is allowed by the  building code
only if it is used as a curtain wall.  This means one has to frame the
house first so that there is not much saved in building effort.

Isn't straw bale too new to have a track record?  Can we assume it will not
powder over time and lose its strength, something we know cob, with a long
track record will not do.

Bob