The extension contains flexible office space. The ground floor is occupied by The Norwegian Library for Talking Books and Braille. The extension is separated from the existing building, whilst retaining relationship of cornice lines, base height and the sheer proximity of new to old.
The floor plans increase by 200 mm in every direction for each floor. This and the twisted geometry, emphasises the extension as an solitary object, yet connected to the existing building.
The structure of the building consists of columns and floors of concrete. The facades are clad with pre-patinated copper in the colour Nordic Brown. Sun-protection is solved by screens in the same colour as the copper cladding.