Cob Structures: Got the "Good Hat" idea, but need help with the "Good Boots" idea

Hello,
I've been kicking around the idea of building something out of cob for some time. I have to finish a barn up that has only a roof. I figured cob would be a fantastic material to do it with. My only question that I can't seem to find a definitive answer for is how to build the "good boots" and the foundation. I have searched this forum, I just can't seem to find anything that really fits what I'm dealing with here. Where I live used to be a bean farm. There is a lot of clay in the soil, and when it gets wet, you get taller when you walk around (sticks to your boots that bad, literally!). The only material I have to bring in is sand.

So here's the question: How do I build a foundation for a cob structure? I've seen flat rock stacked, and gravel type things in pictures, but nothing that really addresses what to use, and how to use it, as a foundation. As I said, the soil here has a high clay content. When it dries, it shrinks so bad you can step in the cracks. When it's wet, it holds water. Since it holds water, I know that cob directly on the ground will be a bad thing... might dissolve the walls!

I was thinking of digging a footer way wider than the wall, so it extends out past the perimeter of the walls about two feet to act like a French drain, but I think the first two feet of the wall would need to be something other than just cob...

The region I'm in is in Clark County, Arkansas. The reason I'm considering cob is because of its ease of construction, simplicity, abundance of materials, and to fight the climate! The summers here can be absolutely Hellishly hot! (105+ for a few weeks) and when it rains, it just rains and rains and rains... We are stuck between the moist air from the Gulf of Mexico, and the cool air coming down from the Great Plains, so the weather can change very quickly. I went to work one day at 6 am. It was a balmy 77 degrees, 800% humidity (yes, eight-hundred)... at 3 pm it was 27 degrees and snowing.

We are also kind of outgrowing our cabin now. The kids are getting a little bigger. We need just a little more space. I am hoping to learn enough with the barn and possibly a picnic/tiki kind of area with fire pit and oven/grill kind of thing to be able to build a suitable home. I also have about 9 acres of cedar for structural use (that's what the barn was started with).

And hey, Paul, and all you other Permie Gurus out there, thanks for being there for us noobs and answering our silly, redundant noob-ish questions.

Rich: Have you been looking at both types of building methods? You might try a combination of tire and bag building. Tires should be easy enough to come by. Go up about two feet with tires and then finish off with bags. You should be able to tie the bags and tires together with rebar... Just a thought. I don't have any experience with this type of building, but based on my research, this is the way I am leaning for building goat barns.

Thanks Chris! Good ideas... however, I'd like to kinda stay away from the whole benzine thing with the tires. Earth bags might be something to experiment with, though.

I got my hands on a copy of The Cob Builder's Handbook by Becky Bee. Awesome stuff! I'm about halfway through it. It did answer my foundation questions. It makes sense. I will have to put a great deal of effort into the foundation with drainage, gravel, rock, and sand. These three critical elements are not at my disposal here, but about 15 miles away is a wilderness/hunting area where those three critical elements are free for the taking, as long as no roads or hunting camps are disturbed. I have a friend who has been camping out there for decades. He knows the area like the back of his hand, and is willing to take me out there for whatever I need.

Good friends are a good thing to have. I think I will start with an outdoor cooking/hangout/firepit area where I can experiment with this fantastic ancient building technique. The clay is the one thing I have an abundance of. My son and I were looking after the animals this morning, and right in front of the barn, I had to use a shovel to pry his boots out of the mud. lol He's seven, probably 55-60 lbs, so he's not a massive little guy, it's just that mud was hungry for boots! And boy does that stuff HOLD water!

Anyway, I'll post pics when I start building.