[Cob] Garden wall foundation

[Shody Ryon]

I do not have experience with this problem, I am only writing from the reading I have done.
You might wish to contact an architect or do an internet search to see what the frost depth is in your neighborhood. there exists a think called "frost heave" which might ruin the wall in a few years, if the foundation doesn't extend below the frost line depth. I believe Portland OR has a depth 14 inches  in the lower elevation areas which might be extended deeper if there were a longer than normal period of colder than normal temps.
That is why I would consider building the foundation as deep as 18". A 2 story house can some times have a foundation less than 14" deep accept for the possibility of frost heave if built in portland, so I would assume that your house has an 18" deep foundation partly because of frost.

--- On Sun, 7/13/08, Dulane <silkworm at spiderhollow.com> wrote:

> From: Dulane <silkworm at spiderhollow.com>
> Subject: RE: [Cob] Garden wall foundation
> To: qi4u at yahoo.com, coblist at deatech.com
> Date: Sunday, July 13, 2008, 1:29 AM
> Thanks for the response. 
> 
> I want to extend a wall from my little round house, just to
> make a 'c'
> shaped privacy area. It would begin under the roof
> overhang.
> 
> My house foundation is about 18" deep. I left some
> holes in the wall to join
> to, but no immediate overlaps for joining to the
> foundation. The ground is
> level, and it would only bear its own weight, with a little
> protective roof.
> 
> The ground drains well and I'm in Seattle, so freezes
> aren't too bad.