Jim, I live in a large suburban town. I started the planning with a trip down to the town permit office. We are on the same page. It was kind of eyeopening to me. They consider anything larger than a "shed" (which is loosely defined) as an "accessory structure". An accessory structure goes up to 600 sq ft, is lower than 16' tall, and does not need frost protection. The last point blew my mind for something that large. I plan on going down past frost - 4' here, although, this winter could change that depth!

I like the pier idea because I didn't want to dig down four feet all the way around, and its less concrete/blocks to deal with. I understand the solid feel and will look into it. I wonder if that large of a footing would change the town's view of the structure? thanks