This is currently the only "basement" we have. It is about 3 feet deep. The "crawl space" under the main part of the house is about 6 inches deep. Our plans are to get as close to a full basement as possible.  We're going to make the house as light as we can, gutting interior, stripping roofing shingles, etc. Then we will brace the house, see how extensive the foundation is, and start digging.