Any wine cellar experts? Or do you know of a good site?

[FortFunFoSho]

Working with my father on a cellar he is building. We are starting to think about how we need to insulate the floor. The book he has deals mainly with factors that affect you r-value, but we are looking for actual materials we can use.

Anyone built their own cellar? Or know of a helpful site on the matter?

Thanks in advance.