42" Elevated Foundation Build in Coastal NC
So, if this is “What is the best foundation system?” I’ll give it a go...

Do not use soil for fill. Use evenly graded “crushed rock”.

You have fill tested to make sure it’s compacted to 95.% density. (You can’t get 100%.) Install it in 6” layers and compact as you go.

When you have that much fill, (over 18” or so) you need to use larger rocks to save money. I’d go with 6” minus. That means you’ll have big big rocks in the fill. By installing a 3” layer of 3/4” minus rock you’ll have a nice uniform layer for the concrete slab and rebar.

Yes you need a base regardless. Do not use wire mesh in your slab...there isn’t an adequate amount of rebar and the slab will crack. Use temperature steel. Do you know how to calculate the amount needed?

A vapor barrier may not be necessary , that high above grade. We’d need more info to decide.

Length of service by your termite treatment depends on strength, quantity, etc.


Btw, if you use 3,000 psi concrete, then by Code you’ll need it tested. Why not use 2500 psi concrete and skip the cost of testing?
Also, that high above grade, why not use wood framing and skip the fill, compaction, etc.?