Architectural Designs

How deep to dig for a rubble foundation when I build a small cob house? Is similar to adobe or caliche weight.

I've just bought land near downtown San Antonio and plan to build a 120 sqft cob building to practice cobbing and to have storage. So far, I have dug a hole 4 feet deep to see what kinds of soil layers I have. It is nothing but that dark gray clay that is rock hard when dried out and sticky when wet. I suspect the bedrock is far,far below since this is a river city. What is the min. depth builders/construction workers dig to when constructing caliche, brick or adobe structures on expanding clay? I thought of making the walls 16 inches thick at the bottom.

Public Comments

1. one meter should be more than enough in normal ground ,if it is hard packed soil and it is just a one story house half a meter will do that is about 2 blocks down
2. ask bldg. insp. when you get permit