What would the warmer floor sip panels on piles or concrete with polystyrene under concrete.
Or do you place the floor sip panels on top of a concrete slab. I have to be 450mm above ground for 100 year flood. How can I find out the best solution.
Options options... Because you need quite a high FFL, I like an economic solution of using a "well known" framed floor combined with relatively 'thin' SIP panels. Timber piles and joists that every builder is very familiar with, and lay SIPs on top, spanning only between the joists @600mm crs. therefore no timber reinforcement is required. SIPs will give you high R value for the floor, airtight and strong... but you need to protect these from moisture underneath. Maybe soffit lining, or simply good quality building wrap, or maybe corrugate steel?
Alternatively, the joists could be inside the core (thickness) of the SIPs.. basically spanning the floor. However a bit more care needs to be taken during installation.