Rooftop extension

“With an ‘optopping,’ or ‘dakopbouw,’ or ‘topping up,’ a new construction is added technically on top of an existing structure.

This offers many opportunities for existing apartments:

  • One increases the building per area in top locations, creating differentiation in the skyline that benefits the appearance of the neighborhood and the city itself.
  • Additionally, one does not need to limit oneself to mere high-rise; various constructions attached to an existing building fall under this category.
  • One can attach an entirely new construction laterally or backward.
  • A combination of both is also possible; one can proceed with high-rise that ‘overflows’ into the side or back, allowing for completely different entrances to the buildings.

Josef Weichenberger Architects, Vienna, Photos by: Erika Mayer, Renovation and heightening Margaretenstra├če

An ‘optopping’ is thus not necessarily the ‘complement’ of an existing building; it can also be a perfectly standalone ‘supplement.’

In this whole process, the intervention of the architect is indispensable. There are many technical issues that require an architectural solution, as a structural analysis and/or feasibility study must be carried out. The architect must analyze whether to opt for steel frame construction or timber frame construction. Also, to ensure the uniformity of the building, the architect must intervene. Lastly, the new construction must also be permitted.

Why ‘optopping’?

‘Optopping’ provides a solution to multiple problems that the current real estate market struggles with.

  • Due to rising land prices and the incessant increase in legal requirements, it is not always easy or financially feasible to embark on a complete new construction (with or without demolition).
  • Additionally, land scarcity in densely populated areas means that the most coveted pieces of land are already occupied, which is problematic as the upcoming concrete stop means we must build more vertically.
  • Finally, ‘optopping’ provides a solution for renovations of buildings that are too young to be demolished but too old to be sustainable.


Shout it from the rooftops!

Crucial in this whole story is that it is a win-win-win for all involved parties.

The funds that come in through the ‘ground value/ground incidence value’ paid by the optopper can be used in various ways. Usually, this involves thorough renovation or modernization of the existing facade or structure, a new entrance hall, but also financing solar panels for everyone, or even a mere capital increase for the reserve capital of the co-owners and capital for the co-owners themselves. To avoid unnecessary inconvenience, these renovations and modernizations are best done together with the ‘optopping.’

The intervention of the architect who carries out the ‘optopping’ is desirable to ensure the aforementioned uniformity of the new structure with the existing structure. In this way, both works are managed simultaneously.

For the ‘optopper’ himself, this is also a complete ‘win’ because, through his rooftop construction, he can place a completely new building on an existing one, and that in a prime location.

Society in general also benefits for two reasons:

  • On the one hand, ‘optopping’ is particularly environmentally conscious; the new construction is not bound by the environmental impact of the existing structure and can, therefore, be made completely passive.
  • On the other hand, architectural creativity provides the opportunity to popularize the future need for high-rise by building ingenious and innovative constructions, both for commercial and residential purposes.

Josef Weichenberger Architects, Vienna, Photos by: Erika Mayer, Renovation and heightening Margaretenstra├če

DGDM builds with you.

Like many new projects, legal issues are also at stake with ‘optopping.‘ One not only has to obtain a permit but also negotiate with the co-owners of the existing apartment building.

Depending on the destination the new construction will have, the legal solution may be different. Since ‘optopping’ itself is not yet legally regulated, various existing legal constructs are possible. One can, among other things, appeal to building rights, new volume ownership, but also an adjustment of the deed of division.

Due to the multitude of possible constructs, a tailor-made legal solution is indispensable for ‘optopping’ projects.”

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Stable legal framework

DGDM guides you through the entire process and ensures complete peace of mind through a personalized, clear, and stable legal framework.