When the Rietveld building was renovated in 1999, a new office wing designed by Greiner Van Goor Huijten Architects BV was added to the southwest side. This enlargement was necessary so that the growing numbers of staff could be located in the museum itself . The offices are not open to the public. It was decided to make the new addition a tall, narrow variant of the previous office block located here, because this form best suits the surroundings.
The office wing is designed as an abstract volume that joins in the play of Cubist forms making up the museum. The glass facade is placed 60 cm outside the structure, like a bell jar over the building. The proportions are in line with those of Rietveld’s building.