SubFloor Acoustic Flooring has been used here for apartments in Sweden.

The flooring acoustically dampens any step noise up to 28 dB and allows you to raise the floor to the desired height. Impact noise between apartments is greatly reduced and installations/wiring can be fitted in the added space.

These apartment floors were assembled from heights of 58 mm to 112 mm with a 22 mm chipboard on top.

System: SubFloor Acoustic Steel System

Products:
Steel Joist 45 x 30 mm
Subfloor Screw 100 mm
SubFloor Acoustic Foot

Construction:
Joist separation: c/c 600 mm
Building height: 58 – 112 mm