building earthbag on expansive clay

I got wind of this site from TSP podcast, which I thought was great. I was hoping to get some help getting information on specifically what to do with expansive clay in re-guard to the foundation phase. I have been studying up on building an eco dome , but with all the reading and the videos they only mention that building on expansive clay is different and they dont go into what to do about it. I have not been able to google anything that has really detailed information on what to do to prep the site before building the structure.  I understand what expansive clay does to normal construction over time, but I'm not so sure as to how it will effect the eco dome. I live in s. central texas, I have done my field tests to find out what percent cement I will need ( 20%)and I'm just about ready to order some bags and get started but I need to fully understand the foundation phase before I get started ya know. I hope someone can help me out!

Well I got word back from the Cal-Earth people, and this is what they suggested..

How do local builders address this.  Some places in California require
> that the ground under the foundation be completely saturated to achieve
> full expansion. Then sustain the water in the ground through irrigation.
>
> My suggestion is to find the condition which is the easier to sustain.  If
> the ground is usually wet then build when the ground is wet.  Remember to
> keep it wet during drought.  If dry, then keep the ground surrounding and
> under dry with french drains, steep grading, paving the surface with
> bricks, plastic sheeting with ground cover, and or stabilized earth.
>
> The impact of expanding or heaving soil on these buildings will be less
> damaging than to rectangular building, therefore, look to local successes.
>
> To maintain the longevity of the barbed wire in the foundation wrap the
> bottom layer with plastic in order to damp proof it and then damp proof
> the exterior with more plastic or below grade waterproofing.
>
> Frank Lloyd Wright had used an idea call a floating footing with some
> success look at this link:
>
> http://cobstudio.blogspot.com/2006/06/rubble-trench-footing_12.html

Now that I have better information I can finish my final design and maybe get the darn thing built this year!

Interesting....  This is good to know.

OffGridGrower wrote:

> Frank Lloyd Wright had used an idea call a floating footing with some
> success look at this link:
>
> http://cobstudio.blogspot.com/2006/06/rubble-trench-footing_12.html

The Imperial Hotel designed by Frank Lloyd Wright survived the Great Kanto Earthquake, the most devastating earthquake in Japanese history.

Here is the hotel:



After the earthquake, a bank to the right burns, while the hotel at left is fine, partly thanks to the large water garden Wright included in the design, along with various seismic engineering.