Install the bearing insulation layer of the new waterproof membrane on top of the dry expanded clay layer. This makes the construction more elastic when people are moving on the roof.

For more stiffness, install two insulation layers on top of each other. This solution load evenly distributes the load from walking and reduces deflection in the expanded clay layer. Two layers also improve the firmness of thick insulation layers.

Fix the bearing layer together with the waterproof layer to the substructure through the insulation layer. If you are mechanically fixing the bearing layer, use fixing screws that penetrate through the old waterproof layer to the insulation layer. In this case no additional holes are made in the vapour barrier.

Flat roof, steel 7
New additional structure:
  • New waterproof roof membrane
  • Mechanical fasteners
  • New bearing layer: PAROC ROB 80t, 20mm OR Bearing layer + reinforcement layer: 2 x PAROC ROB 80t, 20mm
  • Dry expanded clay

Existing structure:
  • Old roof membrane 
  • Old thermal insulation: mineral wool
  • Vapour barrier
  • Supporting structure: corrugated steel