My wife and I are building a bermed home.  We started with large tires approx. 5'x4' (very fat tractor tires).  They are laid as a foundation giving me a 4' high basement. We used a large front end loader as a packer on the tires by wetting them down and drivng on them while moving dirt around very solid now. We are now going to pour walls and roof with concrete before berming it on 3 sides.  The size is 30'x40'x8'. First Question is has anyone done this before?  If so any suggestions?  If anyone knows a reason we can't do this?  How deep should we pour the concrete under doors? We live in West Texas,  not much rain fall and the ground is a very very sandy clay.  We also have large earth bags we plan to use to level areas amd for landscaping. Thanks for the help.