With handcrafted formwork of rough-sawn boards, the high quality of the exposed concrete is continued in the extension building as a reference to the old building. For the system partition walls, feco-feederle was chosen as the most cost-effective supplier. The corridor walls of the offices on the 1st floor and parts of the ground floor meet the architects’ high design standards. Continuous skylight strips with the frameless, flush fecostruct glazing with all-round 20-mm-thin edge bonding transport daylight into the corridor zones. The solid wall and door leaf surfaces have a white finish. The fecotür H70 with Rw,P = 37 dB and visually identical H85 with Rw,P = 42 dB corridor doors have concealed frames and flush door leaves on the corridor side. The flush, lacquered wooden skirting boards are visibly screwed on. By mounting the feco system partition walls on pre-assembled sleeper timbers, the system walls are acoustically decoupled. Together with the high sound insulation test value of the fecowand solid wall of Rw,P = 52 dB with a wall thickness of just 105 mm, excellent sound insulation of the offices is achieved and the coexistence of communication and concentration made possible.