Could the space above existing buildings help answer one of Europe’s biggest housing challenges? Survey results from LIFE Reno Tides partner RoofUz show that housing companies and cooperatives in Germany see real potential in rooftop extensions. The opportunity is there – but turning it into more homes will require simpler assessments, clearer processes and more predictable costs.
Creating more homes within the existing city
Rooftop extensions can create additional housing without requiring new building land. They can also be combined with the renovation of existing buildings, making them particularly relevant in areas where space is limited and energy upgrades are already planned.
To better understand how the sector views this opportunity, RoofUz conducted an exploratory online survey between February and May 2026. The analysis includes responses from 36 German housing companies and cooperatives, together representing around 1.16 million homes. The survey is not representative of the full market, but it provides valuable insight into current opportunities and barriers.
Strong potential, limited implementation
The results show broad support for rooftop extensions as a way to create new homes. Among housing cooperatives, 77% described them as a strong opportunity for urban densification, compared with 57% of housing companies. Only around 9% of respondents saw no relevant potential within their own building stock. Many others indicated that potential is likely to exist, but that assessing individual buildings is still too time-consuming or costly.
Most organisations therefore continue to make decisions on a building-by-building basis. Around 70% take this project-specific approach rather than working with a wider portfolio strategy.
Complexity remains the main barrier
The survey shows that rooftop extensions are not held back by a lack of interest. The main challenge is the combination of economic, technical and organisational complexity. Respondents highlighted uncertain cost-benefit ratios, high planning effort, bureaucracy, structural questions and the lack of proven, repeatable solutions. Previous experience has not always made organisations more confident: many participants said that projects would need to become more standardised before they would consider repeating them.
These challenges are often particularly significant for smaller cooperatives, which may have fewer internal resources available for complex development projects.
Can standardisation create a breakthrough?
The findings also show clear openness to more cooperative and systematic approaches. Fewer than 13% of respondents were negative about participating in a consortium focused on rooftop extensions. At least two-thirds indicated that they would consider using a product standard developed around their requirements. For this to work, however, standardisation needs to go beyond the construction system itself. Housing organisations also need reliable cost information, clear responsibilities, simpler procurement and more certainty about planning, budgets and delivery times.
From potential to practical action
Within LIFE Reno Tides, these findings will help guide the development of better screening methods, decision-making tools and more standardised approaches. The next step is not immediately making a major construction decision. It is helping housing companies and cooperatives quickly identify where rooftop extensions are realistic and worthwhile. By reducing uncertainty early in the process, more promising buildings can move from potential to implementation.
