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Underground extension museum Paleis Het Loo
Underground extension museum Paleis Het Loo
40,000 m³
sand excavation
4,000 m³
underwater concrete
year of construction of palace
Show on map

Ten meters deep digging, right next to and below existing monumental buildings. With the underground extension of Paleis Het Loo by Volker Staal and Funderingen, there will be more space for temporary exhibitions and public facilities and the extensive collection can be better presented to museum visitors.

In mid-2017, VolkerWessels company Volker Staal en Funderingen (VSF) was awarded the contract for the underground expansion of Museum Paleis Het Loo in Apeldoorn. Paleis Het Loo will be substantially renovated and rebuilt over a period of a few years. The contract for the underground concrete building pits, (auxiliary) structures and (re)foundations is one of the six sub-contracts of the total renovation and expansion. 

Underground expansion

The underground extension connects the wings of the current palace with the Corps de Logis (the main building). The extension will include a generous entrance area and new exhibition halls. This will create a beautiful ensemble with the palace, the gardens, the exhibition rooms, the Junior Palace for children and the House of Orange, where the permanent collection and temporary exhibitions will have all the space they need.

In order to be able to expand the museum underground, a ten-metre-deep cofferdam of almost 4,500 m² has been constructed using a multitude of foundation techniques tailored to the subsurface and the location. The large construction pit (De Bassecour) consists of CSM walls anchored and stamped with grout anchors and steel fibre underwater concrete floor anchored with GEWI anchors.

Underground connections

Particularly special are the four underground connections under the existing steel-framed buildings of the palace, which dates from 1686. These construction pits consist of a sequence of jet grout columns or soil injection with underwater concrete. Possible subsidence of the existing buildings will be compensated in advance by dozens of augers that have been placed on a special steel structure.

At the end of 2018 we made a vlog (in Dutch) about this spectacular project:


The construction of the underground extension was completed in June 2019. The reopening of the completely renovated palace is planned for spring 2021. 

Involved VolkerWessels companies

Volker Staal en Funderingen