220 mm partition wall on a double IntraProfil ® CW75 steel structure with 2 layers of 12.5 mm fire- rated gypsum plasterboard GKF(DF)/GKFI(DFH2) on each side of the partition and 1 layer of 12.5 mm fire- rated gypsum plasterboard GKF(DF)/GKFI(DFH2) between the CW75 studs. Sound insulation with 75+75 mm glass wool Rw= 70 dB