Many property owners believe that it is the municipality’s responsibility to ensure that their houses do not get flooded in heavy rain. However, Sweden’s official climate adaptation strategy states that responsibility lies with the property owner.
“We need to increase awareness that the property owner has an important role and that there’s much that can be done that doesn’t involve renovating the entire property,” says Sofie Storbjörk, associate professor at the Department of Thematic Studies—Environmental Change at Linköping University.
Many buildings at risk
Even large municipal property companies may be uncertain about how to go about preventive work. To find new ways of working, the research team has collaborated with four municipally owned companies.
Studying flood risk maps, the researchers found that many of the buildings were located in places with a high risk of rising water levels. This was the case for about half of the rental properties and one third of the buildings used for preschools, nursing homes and similar operations. The researchers carried out on-site inspections at 604 buildings to look for design weaknesses. Among other things, it turned out that one third had openings at ground level and that up to half of the inspected buildings were at risk of wastewater getting into the basement because there were no backflow valves. Many also had open holes or cracks in the foundations or the facade.
A worst-case scenario
The large number of problems made it difficult for housing companies to know how to proceed. The researchers then conducted several workshops with key actors to find new approaches. The participants had to make a list of the worst things that could happen in the case of a flood event. There were a limited number of points: injury to people, evacuation of tenants and damage to technical installations or other critical functions. These feared consequences were then linked to the weaknesses discovered in the buildings. Which of them would likely contribute to a worst-case scenario?
But even among the large housing companies there was a perception that the municipalities bear the main responsibility for the preventive work. The researchers then helped to analyse what the property owners themselves have the power to carry out. It turned out to be a lot. For example, they can move key operations from the basement, install watertight doors, install backflow valves, raise entrance thresholds, make sure the ground slopes away from the building, and reduce the number of hard-paved surfaces.
Help for tenant-owned housing associations and homeowners
The researchers conclude that the best way to work is to start from the worst-case scenario and the weaknesses of the buildings concerned. They also think that it is important that both municipalities and the large housing companies are open about what measures they are taking. That would be very helpful for small property owners such as tenant-owned housing associations and homeowners. Another study published by the researchers in the journal Buildings shows, for example, that tenant-owned housing associations greatly underestimate the risk of being affected by flooding, and that even those affected multiple times have not considered working preventively. A major contributing factor is ignorance.
“It will be much, much clearer what you can do if housing companies and municipalities start to inform people of what they have done. Then, as a layperson, you can copy it,” says Mattias Hjerpe, senior associate professor at the Department of Thematic Studies—Environmental Change at Linköping University.
The research was funded by Länsförsäkringsbolagens Forskningsstiftelse.
Artiklar: Introducing a severe impacts approach to guide adaptation to pluvial floods in residential and public buildings, M Hjerpe, E Glaas, S Storbjörk, Building Research and Innovation (2025), published online 16 april 2025, DOI:10.1080/09613218.2025.2489573
The Patronization of Pluvial Flood Risk and Adaptation Among Tenant-Owned Housing Associations in Sweden, M Hjerpe, E Glaas, S Storbjörk, Buildings (2025), published online 20 januari 2025, DOI: 10.3390/buildings15020300
