Existing joists battened and lined with ply 30mm below top of joist.
IDEAL panels cut to fit tightly between.

Jupiter Edge Zone (EZ) panels used to provide 3 pipes per joist void.
Flow and return pipes as well as circuit pipes channelled through joists.

T&G Screed Replacement tiles laid directly on top of System panels (separating foil protects pipes from glue).
Tiles act as load bearing surface for final stone floor.