Sonneveld House has a steel skeletal structure and concrete floors, enabling it to dispense with loadbearing walls, thus allowing the spaces to be divided with greater freedom. Walls were used only to separate spaces. To create optimal openness and flexibility, on this floor the architects opted to divide the spaces with sliding panels and curtains rather than fixed walls. In this way it was possible for the living room to stretch across the entire length of the house. The bands of windows running the full length of the building admitted a sea of light. When required, the sliding wall provided more privacy. For example, in the evenings Mr Sonneveld closed the library off from the living room and used it as a smoking room.