Do you have any recommendations or comments on the preserved wood basements versus concrete. All weather wood foundations are a fine system and have some special benefits in colder areas. The APWA - American Plywood Association has some good information about such foundations. This is a relatively new system and one which does require special skills and knowledge. As such, it is even that much more important to choose a contractor who is skilled in this type of construction.
Concrete foundations are also very good system.
They can be insulated. Q My home currently has no under-floor insulation and I was thinking of having some installed. My home is heated by electric heat pump. My floor joists are on 32-in centers and they consist of 4x4 posts, so they are not very deep. I think my joists are too shallow for R-30.