Project information

client:                  Rijksgebouwdienst (Government Building Agency)
user:                    Ministry of Defence
assignment:         renovation and interior design
location:               Den Haag
area:                    41,114 m² 
start design:        2006
completion:          2012

The glass roof designed by Sander Architecten covers the inner courtyards of the Ministry of Defense like a camouflage net. The concrete structure with pyramidal roof-lights in a composite material is magnificently designed. Through innovative engineering and cooperation at an early stage, something truly special has been achieved.

The core department of the Ministry of Defence is accommodated in various buildings on Het Plein and the Kalvermarkt in the citycentre of The Hague. In the recently completed renovation the inner courtyards between four buildings have been roofed over as part of a completely new arrangement of the building complex.

In designing the roof, architect Ellen Sander of Sander Architecten was inspired by the theme of defence to create a roof like a camouflage net. Unlike many recent examples of glass roofing over internal courtyards, she did not look for the lightest and most transparent solution but, on the contrary, for a conspicuous sculptural form. This roof is both robust and subtle. The diagonal lineation with a placing at 45 degrees relative to the facades of the buildings avoids spatial conflicts, because the existing facades are not positioned at right angles to each other and have their own dimensional systems. Moreover, the shape of the net helps to unify the different types of buildings that it

 The supporting columns under the roof appear to be arbitrarily distributed, like trees in a wood, but in order to arrive at this unusual positioning several design sessions were held to optimise the admission of daylight and the elegance of the roof.

The realisation of the organically shaped columns, demanded special attention. At the top of each column is a crown with four beam supports. The beam grid between the crowns was poured in situ with a high-grade self-compacting concrete. Highly accurate polyester formwork was used for pouring the concrete roof grid. After removal of the formwork the concrete surface was primed and painted matte white with an elastic coating. The effect is surprisingly austere. The matte finish gives the concrete surface a soft character.

The concrete roof grid is provided with a secondary grid consisting of pyramidal roof domes. The glass sheets have been fitted into grooves in the composite plastic roof domes and structurally glued.  The glass sheets have been fitted into grooves in the composite plastic roof domes and structurally glued. The glass of the domes is covered with a screen print to screen out excessive heat. The screen print displays a hexagonal pattern, inspired by Friedhoff’s ornamented brick facade from. Besides an imposing 18th century listed building, the Ministry consists of several buildings by the government architects Friedhoff and Hoekstra, and later extensions.

Integral development

Sander Architecten is convinced nothing about this roof is standard; manufacturers and advisors were involved from the very beginning of the design process to ensure a truly integral development approach. The certificates and inspections were also arranged before the call for tenders, so that the contractor could set to work with a fully engineered design. Only these conditions could have brought the achieved result.