The four interior columns “organize the center of the structure and situate the family’s space in the music salon, this is a homage to his mother whose piano dominated the orthogonal intersection of the axes and the line of the western apse […].” (Jacques Gubler, Professor, Department of Architecture, EPFL, revue Architecture, 15.11.1987)

The opening of the French doors placed between the central pillars defines a space free of support (3 x 14 m), that the father of the architect called the “transept of the cathedral.”

In 1912, the walls were painted in light colours, with the exception of the entrance hall, the library and the small salon, which were re-wallpapered in jute, and the room of Charles-Edouard on the upper floor, which was painted ochre. The door connecting the library to the salon was walled off shortly afterwards, and the salon was then wallpapered in a floral motif, which was reprinted in 2005 based on known fragments.

The floors of the hallways, the kitchen, and the bathrooms have been re-covered in blue and white checked (partially restored) linoleum. The tiles of the entrance vestibule are white and black checked.