Wooden foundation?

[George Batton]

Hi, I'm new to this site but I've recently gotten into studying real estate investing. There's a house I'm looking at that looks like a really good deal but I've looked around the bottom of it and all I see is wood going into the ground. Is there such a thing as a wooded foundation that complies with building code? If not, is there a possibility that there is concrete behind the wood? The house is about 23 years old and has a nice finished basement and it's in a good area, but I haven't seen any sign of water damage in the basement. I was told that the house was built as passive solar meaning that there are rocks under the house that the sun heats up and heats the house. I'm not sure if that might be why the foundation that you can see is wooden.