Steve,

Thanks for that info. Until I started to dig into it (so to speak) I never knew there were so many foundation options. I was raised in a nineteenth century farmhouse with a dry laid stone foundation, but just assumed that most contemporary work was atop poured concrete or mortared block. I've been playing catch-up with all the modern variations (FPSF, ICF, etc) as well as new twists on old ideas (rubble trench, etc.)

I do have the advantage of good soils on a well-drained site and the ability to drain to daylight. With the exception of a root cellar under one bay, the rest of the area enclosed by the foundation will be an above grade crawlspace. (The central supports for the barn will be footed piers.) I'm assuming that I can just put down a layer of poly and a few inches of sand to keep any moisture from affecting the timbers in the floor.