ROTTERDAM, 16 March 2026 – Rotterdam is accelerating its push to add homes on top of existing buildings through optoppen, the Dutch practice of building upward on flat roofs. With 18.5 square kilometres of flat rooftops across the city, the municipality says the approach could create thousands of extra homes while helping older buildings become more sustainable.
Rotterdam says dozens of rooftop homes have already been completed or are under construction, helped by looser rules and the appointment of an optop regisseur around a year and a half ago. The city is positioning itself as a national frontrunner, turning roof space into a more serious part of the housing conversation rather than a side idea.
Simpler rules for rooftop homes
According to the municipality, the policy around optoppen has been made easier and cheaper in several ways. It is now simpler to deviate from car parking standards, the minimum dwelling size has been reduced, design rules for rooftop additions are set out more clearly in the updated aesthetics note, and optoppen is being embedded in the city’s environmental vision to support faster permitting.
For affordable housing projects, the municipal fee has now also been scrapped following a recent council decision. That lowers the threshold for housing associations, homeowners’ associations and developers who want to explore rooftop construction in Rotterdam.
SOR projects show what is possible
Some of the clearest examples are already taking shape through housing association SOR. The projects named by the municipality include Klapwiek with 44 senior homes, Noordschans with 7 apartments and Meyburg with 12 homes. Bigger plans are also being prepared for Katshoek in ZOHO and Westblake, where optoppen is being combined with wider transformation.
Alderman Chantal Zeegers, whose portfolio includes climate, housing and construction, said: “We are taking major steps with optoppen in Rotterdam. By easing policy, strengthening cooperation and getting concrete projects off the ground, we are making our city smarter, more sustainable and future-proof. By abolishing the additional payment for the affordable segment, we are also rolling out the red carpet for initiators.”
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Support for VvEs and new pilot
For VvEs, the Dutch homeowners’ associations known as Verenigingen van Eigenaren, the process remains harder because decisions can take longer. To help with that, the municipality and the Province of South Holland are asking VvE010 to support VvEs from feasibility check to realisation, including links to maintenance and sustainability work. The first pilot is due to begin this year.
Rotterdam has also started learning and working tables with housing associations, builders and architects to discuss obstacles and possible solutions for adding more homes through neighbourhood densification. The city says that should lead to more transparent processes and, potentially, further policy changes.
Rotterdam draws wider attention
The municipality says the optop regisseur is partly funded by the Province of South Holland and the national government. Rotterdam is now presenting itself as a leading example for other Dutch cities, while also acknowledging that not every barrier can be solved locally. Knowledge-sharing remains a big part of the approach.
That broader attention is already visible. The city points to coverage by Germany’s RTL, which filmed the Santos building in 2024 as an innovative example. Later this year, Rotterdam also plans to publish a practical guide for initiators, taking them step by step from early idea to completed project.
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Why this matters for Rotterdam
For Rotterdam, the bigger picture is clear enough. In a city under housing pressure, with limited room to keep expanding in the usual way, the roof is increasingly being treated as part of the answer. Not every flat roof will become a housing project, but the city is now building the policy framework to make that option far more realistic than before.
More information
More information: www.rotterdam.nl/rotterdam-optoppen
RTL video on Santos building: https://www.youtube.com/watch?v=4qsZxO6PvB8
