Solid materials characterise this building, and there is a connection between the exterior and interior, something which bestows the building with a "cast in one piece" character. The early modernism of the 1920s and 30s was generally characterised by smooth surfaces and light colours. In the 1960s and 70s, however, more robust materials were employed, such as "natural concrete." For this building, polished natural stone was employed on the pedestal.

"Natural concrete" is a concrete surface that was developed by the Norwegian architect Erling Viksjø in the 1950s. This method involves using river sand as an aggregate in the concrete. After the concrete is poured and the formwork removed, the concrete is sandblasted and small stones are flushed to the surface.

The windows and glass parapets were replaced around the year 2000. The original windows had teak frames, while the new ones have brown anodised metal frames.