Cob: Re: thick walls, foundations

[John Schinnerer]

Aloha,

> People on this list have said in the past, that the cob houses that have
> survived  in England, tend to have massively thick walls, from 3-6 feet
> thick?

Yeah, 3-4 feet according to most sources.  This has been attributed to the
methods and materials of the time - only earth from the immediate site was
practical for building, which meant that the mix might be a poor one
compared to "modern" cob, where fossil fuel powers vehicles that bring sand
and/or clay from (relatively) far away to create a better mix.  Straw was
apparently often of poor quality also.  Thus the extremely thick walls to
make up for the structural shortcomings of the cob used.

> Many have a fairly high plinth--the stone base.  Of
> the pictures on the web I've seen, I haven't noticed any plinths--in
modern
> cob houses.  I know I would certainly want one, to prevent the base from
> eroding away.

All the cob structures I've seen or worked on have a hefty stone foundation
rising well above the ground to keep the base of the cob wall dry.  Quite a
few pictures on the cob cottage company site
(http://www.deatech.com/cobcottage/pics/) show this clearly.  Some also
show foundations that appear quite low, or have been plastered over almost
to the ground...not a good idea except in very arid climates.

John Schinnerer, MA
-------------------------
- Eco-Living -
Cultural & Ecological Designing
Human Habitat Design
john at eco-living.net
http://eco-living.net