Rock & Wood Foundation

[Winn Cook]

I live in Durango, Colorado and am thinking of putting in an offer on a home that has a foundation made of wooden beams and large rocks.  It was constructed in 1946 and is slightly unlevel in parts.  It is a small home, about 700 square feet and has been lived in continuously for 30 years.  

My question is if anyone has experience getting a home appraised with this style of foundation?  There is some risk that it will not be appraisable, but I still think it is worth my time.  Any tips or advice on this issue would be very much appreciated.