Piecemeal post and beam frame assembly

[Don P]

A rose by any other name, if a 2x4 starts as a log, call it log construction and we're good.

My objections to piers are mainly twofold, first is overturning, you have what are called constrained piers now, the slab is locking them from overturning. Second is independent settlement, each one finding a different depth to settle to depending on soil and differing loads. Hope its not an issue.

Read up on frost protected shallow foundations, that is the foam skirting you are talking about. I think it'll be in chapter 4 here, some climate data may be in chapter 3, can't remember for sure;
https://codes.iccsafe.org/content/VRC2015
that's my state, yours will read the same.

The biggie for frost heave is it requires moisture. We build to frost depth as a worst case preventative but in reality if you can keep the moisture down or if the soil is free draining it can't heave