Non-capillary PAROC stone wool is the ideal material for under-slab insulation. For loads up to 20 kPa (equal to a 2000 kg load), use the PAROC GRS 30 ground insulation slab. For loads larger than 20 kPa, use extruded polystyrene (XPS).

Ground floor 2
  • Floor covering 
  • Floor board
  • Step sound insulation: PAROC SSB 2t
  • Vapour barrier: plastic foil
  • Supporting structure: Concrete slab
  • Thermal insulation: PAROC GRS 30
  • Capillary break: gravel

Passive house structure:

Ground floor, passive house

  • Floor covering
  • PAROC SSB 2t (d1)
  • Wall vapour barrier extended at least 500 mm under the floor
  • Concrete slab
  • PAROC GRS 30 (d2 = edge area; d3 = mid area)
  • Gravel
  Block of flats
Recommended U value W/m2K  ≤0.08 - 0.10
d1 mm  25
d2 / d3 mm  330 - 400 / 250 - 350
Total insulation thickness mm   355 - 425 / 275 - 375

According to definition of a passive house provided by the Passive House Institute, the annual heating, cooling and primary energy demand should not exceed certain values. Although good thermal insulation plays a major role in achieving the Passive House standard, it alone cannot ensure compliance. The requirements for other building components and devices can be determined by various calculations tools, such as Passive House Planning Package (PHPP), available at