This building was exciting to see (I am an Engineer after all). It is a wood foundation. To be clear, a wood foundation is not normal and customary practice in this area. We are aware of a total of three such whole-house constructions in New Hampshire. However, wood foundations are permitted by the Building Code and, if properly maintained/repaired, we believe this foundation could continue to serve adequately.
We would be excited to see and assess the structural integrity of your unusual building construction, if you want to buy, sell or simply repair one.