Nearly half of French homes face climate risks, INSEE finds

Researchers Mathias André, Inès Moutachaker, Sacha Nass, and Julie Sixou analyzed the characteristics of the housing stock and households alongside detailed maps of four climate hazards: expansive clay soils, wildfires, river flooding, and coastal submersion. This approach allows for a broader assessment of geographic exposure beyond past disaster events.

Expansive clay soils pose the most widespread risk, potentially affecting around 34% of current housing stock. This phenomenon refers to the movement of certain clay soils based on their moisture content, potentially impacting building foundations and causing cracks. However, exposure does not confirm the existence or severity of any structural issues.

The study estimates that 8% of homes are exposed to at least two of the four identified risks. This overlap complicates risk assessment, as a single property can be subject to multiple, distinct issues requiring different prevention measures.

The INSEE report specifically mentions the Gironde, Nord, and Pas-de-Calais regions as particularly vulnerable. However, it emphasizes that risk levels vary significantly within these departments, depending on the specific location and type of hazard.

Interestingly, the study revealed a complex relationship between economic status and risk exposure. Housing occupied by higher-income households generally faces greater risk, except in the case of coastal submersion. Conversely, the relationship between risk exposure and the income of homeowners is more complex and often decreases with income levels.

This distinction between occupants and owners is crucial, as the risks affecting daily use of a property may differ from those impacting the owner’s assets. The study presents statistical data on exposure and does not establish a causal link between income and risk.

The findings underscore the need for households to assess risks specific to their address, rather than relying on national averages. For local authorities and real estate professionals, the data highlights the importance of combining geographic information with building conditions and prevention needs. The report does not predict future insurance premium increases, housing price declines, or construction costs, as these factors are influenced by numerous variables. However, it demonstrates that adapting the housing stock is already a significant concern for a substantial portion of French homes, with highly variable local situations.