I was up at the mountain last night - cleaning ditches and leveling the road with the loader. I got a chance to visit with some of Structures' sub-contractors as well; nice bunch of guys.
It looks like the foam forms for the foundation are set and sealed. Each form section was laid individually and the space between them was filled with dense spray foam. Here's a closer look...
[Each form measures about 6' long by 3' wide by 2' tall.]
[Next, gravel then concrete.]
[Concrete will be poured level with the top of the forms.]