Frame/foundation connection

What are some ways to anchor a stud frame to an uneven foundation, such as stone or stacked urbanite (scrap concrete)? I have built a cob home on an urbanite stem wall, but the cob conforms easily to an uneven base, and the walls are also heavy enough that they don't need to be anchored down. Some ideas. (1) Attach a thick sill, like in a timber frame, to the stem wall, which would be stiffer and easy to level, then build off of that. (2) Pour just enough concrete on top just to level it out. In both of those, I still need a way to tie the wall to the weight of the stem wall. Maybe some long rods that go through the stem wall and are cast into blocks of concrete at the bottom of the rubble trench. Other ideas?

I like your idea of casting rods into the stem wall and attaching this to your frame. Possibly you could even just fasten bolts directly into your stem wall by making a level platform with concrete as long as it is substantially thick enough. Another option is to do what straw bale builders do when building a load bearing wall and want to anchor and compress the bales. Run an opening (4 inch tubing) under your stem wall and use high tensile wire to secure a bond beam in place. If you can keep the urbanite relatively level during building you could also think about using earthbags as final layer to give a more level stem wall to attach your stud frame on. Anyone got any other ideas?

One of the goals on the small house I'm designing is minimizing concrete. So leveling the top of the urbanite with concrete would be great, but I also would like something more massive to tie the house down to. That's why I'm thinking if I can tie it to some anchors at the bottom of the rubble trench, I have all that weight of the rubble holding it down. Maybe a combination: rebar cast into some blocks at the bottom of the trench, and also cast into a level bond beam at the top of the stem wall, which also has anchor bolts set for the sill.
Your house looks awesome. Would love to find a time to look through your whole blog. How big is it? I'm trying to squeeze a design into about a 300 sq ft footprint for our first couple years' shelter on our new land in Colorado.

Thanks. The house is somewhere around 350 square feet with the loft. Definitely glad I went that small.

I would say implementing a few different techniques is a good idea, that way you get the most secure attachment. Definitely post some photos as you go along. I would love to see it.

Look in code IRC Foundations no need to try and reinvent the wheel.

Actually I feel like much of natural building is all about reinventing the wheel, the "wheel" being conventional, code-prescribed building practices that are restricted to industrial, manufactured materials. As I said, a goal for me is keeping concrete to an absolute minimum.
I am not familiar with the IRC, and have no particular desire to delve into it. Is there a particular section you know of that addresses my question?

Rebar cast in concrete blocks at the bottom of your trench sounds like a good idea. In framed buildings, you really should have each piece of your building mechanically fastened vertically to the next from the roof all the way down to the bottom of your foundation so the roof doesn't blow off in a gale. Don't depend on gravity and nails to keep it all together. They make lots of different kinds of strapping for attaching one piece to the next. Tennons and pegs, or dovetails will probably work for the larger wooden members if you want to minimize steel and costs.