Cover the ground with plastic foil or insulation to reduce the amount of moisture underneath. Insulate the foundation from both sides. Install frost insulation in ground around the house to keep the whole structure from freezing.

The structure of ventilated floors is very similar to wall construction. 

Ventilated floor
  • Floor covering 
  • Floor board
  • Vapour barrier, plastic foil
  • Supporting structure: Timber joists / PAROC eXtra
  • Wind protection insulation: PAROC WPS 3n
  • Support for wind protection insulation
  • Frost insulation for foundation: PAROC GRS 30
  • Ventilated space

Insulation solution with U value
PAROC eXtra (floor joists) 175 mm   100 mm 100 mm  125 mm  175 mm
 PAROC eXtra (floor joists)
100 mm 150 mm 175 mm 200 mm
 PAROC WPS 3n 55 mm 55 mm 55 mm 55 mm 55 mm
 U value, W/m2K 0.17 0.15  0.13  0.11 0.09 

Passive house structures

Ventilated floor can also be used in passive building.
Ventilated passive house floor
  • Floor covering
  • Flooring boards
  • Vapour barrier (tape all joints)
  • I-Joist / PAROC eXtra (d1)
  • PAROC WPS 3n (d2)
  • Ventilated space
  • PAROC GRS (on the exterior side of foundation)
  • Frost insulation (XPS / EPS )
  Block of flats 
Recommended U value W/m2K  0.08 - 0.10
mm  350 - 450
mm  50
Total insulation thickness mm  400 - 500
According to the 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 the Passive House Planning Package (PHPP), available at