Cob: Good Foundation?

[lightearth at onebox.com]

Hey Michael, good to hear from a fellow Great Laker!

We have and do use rubble trench foundations that are about 24-28 inches deep and well drained here in Wisconsin and N. Illinois. There's a drain to daylight coming out of the foundation + insulation board around the outside of the foundation (foam unfortunately) and there's also swales that divert surface water away from the foundation just a foot or so outside of the footprint of the building.

No bad experiences with doing something like this yet and don't think there will be......the river stone that we use just won't heave unless it's completely filled with water and flash frozen (then the water heaves of course)...the rock provides a good substrate to support whatever your stiff foundation is that comes above grade for your cob, in my opinion. Cob seems to do better on top of 'jagged' foundation so the rubble trench allows the possibility of broken concrete chunks and rocks on top of it for the Cob to key into.

Also I worked on a strawbale project in Indiana where there was a rubble trench topped with a poured, reinforced, cap over the rubble. That seemed to work pretty good, too concrete intensive, but flat for the strawbales too.

Chuck, are you there ? Great Lakes question....tell them about your choice of foundation too....

Marlin

p.s. let me know in Michigan how the insulating/non-insulating choices with Cob go.


     Marlin Nissen
   - Outta The Box-
  lightearth at onebox.com
(608) 213-9405  Cell/voicemail

"Nothing great was ever achieved without enthusiasm"  - Emerson



-----Original Message-----
From:     "Amanda Peck" <ap615 at hotmail.com>
Sent:     Tue, 29 Apr 2003 07:59:57 -0500
To:       coblist at deatech.com
Subject:  Re: Cob: Good Foundation?


Welcome to the list.  I'm not official, but welcome anyway.

I'd consider rubble trench or well-tamped gravel for the foundation, 
especially if you have to go that deep (and, remember, WIDE--two or more 
blocks worth).  The log-house guy helping me this spring was a bit dubious 
about that until he talked with some friends that are working that way up in 
Kentucky, then he became moderately enthusiastic.  Of course it hasn't stood 
the test of time in my (difficult) site yet.  His friends in Kentucky (need 
deeper foundations than here where they are usually only about 18 inches, 
but not no four feet) only went down about a foot.  Don't know if that's 
good or bad, but it would bear research.
..............




I am considering a small 200 sq. ft. outbuilding. Can I use concrete 
stabiized earth block for the foundation (foundations are 4' deep in 
Michigan) or will I have to buy cinderblock?

Michael Fitzgerald
Anthropologist/Woodcarver/Puppetmaker



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