Cob: RE: Cob insulation idea

[lightearth at onebox.com]

Subject: RE: Cob: insulation idea
Date: Sat, 12 Oct 2002 10:43:48 -0400

Hi Jen,

What we're doing in Wisconsin, USA is to 'sandwich' strawbales, laid on their side, between an inner and outer cob wall. The cob walls are aprox. 5 inches thick on either side. This creates the need for aprox. 28" or more thick foundation walls which is the downside. To make the foundation simple and cheap (and urban local) we like rubble trenches with urbanite (broken concrete) stacked on top of the rubble trench (a detail on itself).

 Also the inner and outer walls need to be tied together in several places to stabilize them. This we can do with 28 inch 2 X 4's scrounged from construction sites as cross ties, nestled in the bales. Interestingly the strawbales act as additional stabilizing support and are stacked like concrete blocks with the seams half-way across the one below.....

Best of luck, we have similar needs and my observation is that standalone Cob is NOT adequate insulation for COLD climate winters and requires large amounts of internal heat added.....but we want to sculptural, empowering, low-tech solution, low-cost options that we were taught by Cob Cottage.....kudo's to Cob Cottage for infecting us with the ideals, it's up to us to adapt them for our particular areas!

Marlin Nissen


-----Original Message-----
From:     "jen walker" <jwalker at magma.ca>
Sent:     Sat, 12 Oct 2002 05:04:05 -0400
To:       coblist at deatech.com
Subject:  Cob: insulation idea

Hello again cob folk,
So I'm gathering as much info as I can, hoping for assurance that a cob
cottage could fly in West Quebec where it can sometimes be -40 celcius (but
generally -20 celcius) in the (usually very sunny) winter.
So far I've figured out that the following could help us along... As much
passive solar design as possible, less windows on the north and west sides
and the addition of a slip-straw mix to either the whole building or at
least the north and west sides. Also lots of inside cob to retain warmth in
the house. I was thinking of a lime based plaster to protect the place from
drifting, melting snow against the house (also wondering if snow would help
insulate).
My idea is what if an inside cob wall was built parallel to the north/west
wall area (like a panel). There would probably have to be breaks in it for
windows. Anyhow, perhaps the gap between the walls that would be created
could be stuffed with straw, fleece or whatever just for the winter then
removed in spring and a fresh lot of dry material inserted the following
cold season. The gaps could be closed somehow at each end (even with
cardboard) to prevent dust perhaps. Is this crazy, would it make a
worthwhile enough difference?
I'd really appreciate any comments on this plan that could improve it or
pointers where we may be going wrong.

Thanks,
Jen Walker & family