During the refurbishment works up to the year 2000 substantial parts of the complex and extensive technical services were placed in the basement of the house with its 6,200m² gross floor area, since from the point of view of the monument protection an arrangement outside the building or on the roof was not possible.

Because of the groundwater levels which have risen by approx. 1.0 m since the refurbishment, parts of the basement and the walls have been subjected to the pressure of ground water, which the existing waterproofing does not withstand.
In the medium and long term the operation of the Bundesrat can only be ensured by the subsequent installation of a waterproofing system in the basement conforming to regulations. Within the framework of the waterproofing measures, parts of the technical installations, routes and pipes will be removed from the existing basement and partially transferred to newly built rooms. Furthermore, the access routes will be optimized.

The refurbishment takes place during the ongoing operation of the Bundesrat and the print shop located on the ground floor. Construction procedures, construction site accesses, building site equipment and storage areas as well as safety, cleanliness and noise protection are planned and implemented in such a way that the sensitive operation of the Bundesrat can be maintained at any time without substantial restrictions. The construction is carried out in small construction sections due to the building services that need to be maintained functioning.