Just crawlspace, no basement. No subfloor. The car deck is completely sufficient.
The entire house is built on trapezoidal piers that I have poured 8 feet on center. (My snow load is engineered to 55 lbs !!)
I have structural steel footer collars cast into the exterior perimeter piers that act as the base for my timber post columns.
The entire structural joinery system is pre-engineered by a company out of PA called Socket Systems. The columns are free-span, tilt-up and seated into the collar by pinning to the footer. The wood sits about 2" above the surface of the pier.
Immediately above the collar on the base of the column, there is a 2x12 hanger plate lag bolted to the timber columns creating a full perimeter. The joists are then hung from this perimeter by inserting them perpendicular between the outside perimeter and the field laminated 4x12 ((2, 2x12s lag bolted together)intermediary cross beams that are pinned to #4 rebar that I cast into smaller, interior support piers. Rebar sticks out 4 inches above top surface. Cross beams are pre-drilled in center and matched up to rebar pins.
Vapor barrier and insulation fill between joists and the car decking is pinned on the top surface across the joists.