Introduction

THE TOP REVOLUTION

The benefits of topping are many, and it's not hard to see why. First, it offers the opportunity to create tens of thousands of new homes at existing locations. This is done without having to demolish the existing buildings, but by recycling them, as it were. This process makes it possible to reuse scarce building materials and provides significant energy savings. In addition, the residents of the buildings do not have to leave their homes or only temporarily while the topping is being completed: the structure is often manufactured in a prefabricated factory and can then be installed on top of the existing building within a few days, without much inconvenience to residents.

Another important advantage is that a roof structure must be light, which leads to the use of materials such as wood or other bio-based alternatives. This not only contributes to saving energy, but also to storing CO2 in the long term. Perhaps the biggest environmental benefit of topping is that it saves green areas. This is not only crucial for biodiversity, but also for water management: less pavement means more space for nature to absorb rainwater effectively.

There is also a financial advantage for privately-owned apartment complexes: the proceeds from the newly built homes benefit the community. This income can then be reinvested in making existing real estate more sustainable, for example by installing insulation or providing the building with heat pumps and solar panels. This increases the value of the existing apartments while reducing energy consumption and associated costs (Den Butter, 2023, para. 3)

Housing crisis
Sustainable Renovation
Maintenance
Climate Change
Press
Het Parool
In Buitenveldert and Oost, existing houses are being built: “We can add 8,000 homes to the city in this way”
August 3, 2024
AT5
Upstairs: topping up is on the rise, but on a large scale still a long way away
May 20, 2024
Architects' Journal
Vertical building extension method Topping launches in the UK
November 28, 2024
FD
Up to the roof: tackling housing shortage with 'topping'
For outgoing housing minister Hugo de Jonge, topping up is one of the ways to quickly build additional homes, now that the new construction production...
Presentation

We show that it smarter can

A.J. Ernst Street 700
‍pre topping

€60,000 - €100,000 renovation costs per apartment
costs per apartment

A.J. Ernst Street 700
‍After Topping

20 extra homes
> €800,000 paid out to the homeowners' association (VVE)
Sustainably maintained
A+++ new energy label
18% increase in property value

Focus on Sustainability

By prefabricating with wood and other biobased materials, these materials store CO₂ instead of emitting it.

A.J. Ernst Street 700
‍Before Topping

€60,000 - €100,000 renovation
costs per apartment

A.J. Ernst Street 700
‍After Topping

20 extra homes
> €800,000 paid out to the homeowners' association (VVE)
Sustainably maintained
A+++ new energy label
18% increase in property value

Focus on Sustainability

By prefabricating with wood and other biobased materials, these materials store CO₂ instead of emitting it.

The potential of summits in the Netherlands

“Realistic task of adding around 100,000 homes through summits”
Research by Stec group.pdf
Research CCS.pdf

10% of the Housing Challenge by 2030

With 100,000 potential new homes on top of existing buildings, optoppen can fill as much as 10% of the total housing challenge by 2030. This makes it an indispensable solution in the fight against the housing shortage, especially in urban areas where space is scarce.

The potential of topping out in Amsterdam

The potential of topping out in Buitenveldert

The potential of topping out in Buitenveldert

The potential of topping out in Buitenveldert

The potential of topping out in Europe

The potential of topping out in Amsterdam

The potential of topping out in Buitenveldert

The potential of topping out in Buitenveldert

The potential of topping out in Buitenveldert

The potential of topping out in Europe

Topping up at the World Urban Forum of the United Nations in Cairo, 2024

At the World Urban Forum in Cairo (2024), experts explored summits as a sustainable strategy for urban expansion. The discussion emphasized the role of summits in addressing housing shortages, while maintaining existing infrastructure and minimizing environmental impacts.

Stop at Pakhuis de Zwijger in Amsterdam, 2024

At Pakhuis de Zwijger in Amsterdam (2024), industry leaders presented concrete applications of summits in the Netherlands. The event showcased innovative projects and strategies that effectively integrate vertical expansion into urban planning.
Explanation

Top up interpreted

Foundations, technical connections, costs and benefits and the trias energetics. We make these videos and guidelines to explain summits to everyone.

Financing

Discover how, as a VvE, you can finance the sustainability of your apartment complex. From subsidies to innovative solutions such as topping - we cover all options to make your building more energy efficient. This practical explainer shows how you can pay for the investment and what it brings: lower energy costs, a higher home value and a smaller ecological footprint. With concrete examples and clear explanations of available regulations such as the VvE Energy Saving Loan and subsidy options.

Trias Energetics

The Trias Energetica forms the core of effective sustainability of a building: first minimizing energy consumption through insulation, then using renewable sources such as solar panels, and finally the efficient use of any fossil energy. This proven method maximizes your sustainability return.

Technical connection

Connecting a topping to an existing building involves various technical challenges. From fire safety and noise control to the connection of utilities such as water, electricity and ventilation. With the right expertise and controls, we ensure a safe, comfortable and seamless connection between old and new.

Foundation

When erecting buildings, the foundation plays a crucial role. Not every foundation can carry extra floors just like that. By making smart use of light materials and various construction methods - such as an intermediate or table construction - we still make topping possible. Post-war buildings in particular offer opportunities for this because of their often oversized construction.

Type of congestion

Mega Optoping
Transformation & Topping
Popups in occupied condition

Guidelines

Flora & Fauna.pdf
Fundering.pdf
Aansluiting.pdf
Erfpacht.pdf
Congestions

Topping up is a global phenomenon. We figured it out

Find out more at at toppen.org

Did you know that the solution to many urban problems simply lies on our roof? Literally. Topping up, or topping up, is the way to make our cities smarter, more sustainable and more efficient. By adding extra floors to existing buildings, we are not only creating more space, but also building a cleaner future.

How does that work? Simple. With light roof structures made of wood and biobased materials, we turn empty roofs into carbon sinks. Yes, you read that right: we store CO₂ in the city. At the same time, we make use of what is already there. No new land, no new infrastructure required. Less waste, more value.

Smart building for a smart future


Topping up isn't rocket science. It's common sense in action. More space, less impact. It fits seamlessly with circular principles: building with materials that do not burden the Earth and make buildings more energy efficient while we densify. As Kelly Harrison from Whitby Wood puts it:
“Do we really want to move forward? Then we need to work together and share our knowledge.” That's why pioneers such as Creative City Solutions, Holland Houtland and Built by Nature are collaborating on an open-source platform. A place where owners and urban planners can easily see: What's possible on my building? How much value do I create? How much CO2 can I save?

Topping up: more than building

This isn't hype. This is a movement. It's not just about extra floors, but about a future that we're building smarter together. With Optoppen, we are transforming cities — layer by layer, roof by roof. Because the solution? It is already ready for us. All we have to do is look up.

Vertical

Expanding vertically and making it more sustainable can be complicated & expensive...

Complicated regulations by type of owner
Housing Corporation I
Housing Corporation II
Investor (s)
Owners Association
Owner-occupant
100%

The owners should like it..

Vertical extensions are often pilots
High development costs
Specialized knowledge and
Complex network of companies
Fragmented ownership
Voting rights (participation)
Inspiration

All you can imagine is veritable

— Pablo Picasso

Le Taureau - Picasso

Where ideas become reality

With this statement, Picasso means that the imagination creates a form of reality — as soon as something exists in your head, it already has some kind of right to exist. In art, but also in architecture, innovation or dreams: the boundary between fantasy and reality is fluid.

Top Up: The Art of Omission

Urban renewal does not start with building more, but with smarter construction. Like Picasso in Le Taureau reveals the essence by omitting unnecessary details, we are building the city of the future. Not through large-scale expansion, but by making smart use of what is already there.

Adding value without waste

Traditional construction projects consume resources and take up valuable space. Optoppen takes a different path: with light, sustainable materials such as wood and biobased structures, empty roofs turn into valuable places — in the middle of the city. No new foundations, no large-scale interventions. Less concrete, more nature. Less CO₂, more living space.

The Power of Simplicity

Optoppen is about sophisticated interventions that make an impact without burdening the city. Just as Picasso captured the essence with one smooth line, we create space without unnecessary ballast. The optop revolution is revaluing the city itself — building with vision and respect for what is already there.

The future does not lie in breadth, but in height

The Optop Revolution
Sustainability, densification, improvement

See how we go about it
Conclusion

Building smart cities,
one roof at a time

Optoppen is transforming the city by building more efficiently, sustainably and future-proof. Instead of expanding outward, we're building upward — new homes on top of existing buildings, while maintaining resources and minimizing environmental impact.

We explore innovative construction methods, sustainable materials and smart urban solutions to use space without waste.

Get involved and contribute to the future of housing and urban development.
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The content of this website has been compiled with the utmost care. However, the possibilities for sustainability and their results depend on the concrete situation on site. On this website, we only provide general information about sustainability and renovation; the information on this website is therefore not intended to provide concrete advice or guarantee of a particular result and cannot be construed as such. For this reason, you cannot derive any rights from this website. Creative City Solutions BV also accepts no liability for using the information on this website.