Good evening. I was looking at some alternative construction and found "earthship" building that basically build into the ground but uses old tired rammed with dirt as the walls. While reading about this type of home (not as appealing as a log home) I started to think about the savings that could be had IF that type of wall could bear the weight of a log home. One of the FAQ's on the website is as follows:

"Q. Do I need to use a concrete foundation under the tire walls?
A. A concrete foundation is not necessary because tire walls are so thick (2-1/2' for rammed-earth tire walls and 5' for tire bale walls). Both the rammed-earth tire wall and the tire bale wall have just at twice (almost 4X for the bale wall) the bearing surface of a standard concrete "footer". The key to the difference is in the "footprint" of the wall. A framed wall needs more footprint to hold up the roof, a tire wall doesn't."

The question is, what is the ability to bear the weight of the log home above. Does anyone have any ideas? Of even the answer?

Thank you

Eric