Call me lazy - but the spot in our backyard where I want to build, used to be the neighborhood sand/rock dump for mixing foudations for the neighboring homes. It is literally 100% coarse sand and rock mix (rocks about 8 inches in diameter). Am I wasting my time digging a foundation? Seems silly to dig rocks OUT just to replace it with... rocks. Drainage won't be a problem, because it's near the top of a small slope. Does the concept of frost heave only apply to soil and things that retain moisture? What I would like to do is get some 2-3 ft. diameter boulders delivered from the neighboring rock pit, arrange them in a circle, and cob on top of that. (The cob comes from the same neighboring pit. Roof will be a huge overhang of repurposed old metal shed roofing.) The location is Spokane, WA (eastern WA) - frost depth is 2 ft.
