For Owners

Adding Extra Floors and Converting Buildings Could Deliver 2.7 Million New Flats


March 2019

The lack of development land is one of the biggest obstacles hampering efforts to combat the housing shortage in Germany. Especially in the conurbations, where the housing shortages are most pronounced, undeveloped land is extremely hard to come by and very pricey. The high relevance of urban infill densification has therefore been the subject of frequent discussion, and all the more so after a survey published by the University of Technology at Darmstadt in 2016 suggested that 1.5 million new flats could be created by adding floors to existing residential buildings alone. The same university lately expanded its survey to include non-residential buildings – and identified enough potential for another 1.2 million flats in the process (source:  

Steady Decline in Infill Densification in Germany

This means it would be possible to build a total of 2.7 million new flats, and to do so without any need for undeveloped building land or the provision of entirely new infrastructure. According to the survey, 1.5 million flats could be created on top of residential buildings raised between the 1950s and 1990s while another 560,000 flats could be accommodated on top of existing office and administrative buildings. Add to this an additional 400,000 flats on the roofs of single-storey discount supermarkets and other retail buildings, 20,000 flats on top of multi-storey car parks and 350,000 flats by converting vacant office and administrative buildings.

The stated goal of the Federal Government is to ensure the completion of 1.5 million new flats by the end of 2021 so as to relieve the gravest housing shortages. This objective and far more could be achieved solely by adding extra floors to existing buildings, and it would thus be advisable to seriously step up infill densification measures. Yet the reality on the ground looks very different, as the number of planning permissions for existing-building retrofits declined by 8.4 percent over prior-year period during the first eleven months of 2018 (source: In 2017, the sum total had already dropped by a hefty 19.5 percent (source:

Survey Provides Many Recommendations for Action

It appears that something is going to have to change, and even the survey by the University of Technology at Darmstadt emphasises that the current framework conditions are not suitable for raising the potential for new apartments. This prompted the survey authors to call for amendments of a number of building code and planning law requirements. They urge a simplification of adding extra floors, for example by permitting developers to exceed the approved number of floors, by lowering the requirements for handicap accessibility or by waiving the mandatory number of parking spots.

Permit procedures for adding floors should be simplified or abbreviated in their opinion while changes of use should be made easier. They also propose government allowances for adding extra floors, for example by creating a special depreciation allowance for builders. The available options for addressing the housing shortage are numerous, or so the survey by the University of Technology at Darmstadt suggests, but whether the body politic will act on these recommendations for action is a different matter altogether.

Further readings

For Owners

Insulation isn't everything - smaller measures with a big impact

10. May 2024

Insulating the façade is one of the most important measures in the energy-efficient refurbishment of a building. Find out here how you can successfully reduce the energy consumption of your property.
Continue reading
For Owners

The new property tax: questions and answers at a glance

19. March 2024

The property tax reform in Germany: What will change for owners and tenants? Berlin responds with measures. The questions and answers about the new property tax now in our ACCENTRO blog.
Continue reading