France: The Impact of Extreme Weather Events and Adaptation Solutions

To anticipate flood risk, the first priority is to strengthen protection on lower floors and limit the installation of critical equipment in these areas. This can include using rot-resistant, non-water-absorbent materials (such as tile), installing water detectors, or waterproofing basements.

In some exposed areas, it may even be useful to elevate building structures. Green roofs can retain rainwater and help prevent drainage systems from being rapidly overwhelmed.
At the urban scale, drainage systems can also be oversized to accommodate higher flow rates. Retention basins or levees can also be installed to slow water runoff and prevent erosion.

After a flood, repair work should focus on thoroughly drying out and remediating the structure to prevent irreversible damage to the building. Any material in poor condition—meaning extremely damp, waterlogged, or showing early signs of rot—must be removed and replaced.

If water has severely weakened a building’s structure or foundations, repairs may also require resin injection, sealing, or structural reinforcement.

The first priority is to keep heat from entering buildings through high-performance thermal insulation, particularly in roofs and walls, solar-control glazing combined with movable shading solutions, and high-albedo finishes. Materials with high thermal mass can then help retain cooler indoor temperatures.

In addition, nighttime ventilation helps release heat accumulated during the day, while ceiling and other air-circulating fans improve perceived comfort. At the urban scale, vegetation and high-albedo ground surfaces also help reduce the urban heat island (UHI) effect.

Unlike other climate hazards, heat causes less direct physical damage to buildings. Nevertheless, when rising indoor temperatures become unavoidable, remedial solutions need to be considered.
The main option is to install cooling equipment—such as adiabatic cooling systems, district cooling networks, or air-conditioning systems—used in a targeted and measured way. These systems can cool either an entire building or shared cooling refuges, for example at the neighborhood scale.

Because drought is closely linked to water stress, it requires optimized water management through rainwater harvesting, graywater treatment, and interconnected water networks. Increasing surface permeability is equally critical: reservoir-structure pavements and vegetated permeable parking areas can store rainfall and promote infiltration.
However, vegetation must be carefully managed and should not be planted too close to buildings, to avoid drying out the soil around foundations. Finally, to prevent risks associated with the shrink-swell behavior of clay soils and protect buildings, other structural solutions are available, including geomembranes, resin injection, micropiles, and innovations developed by Cerema.

Once buildings have been affected, ground movements associated with the shrink-swell behavior of clay soils require major structural interventions.
Repairs may include treating cracks with specific coatings combined with fiberglass mesh, or using structural tying, stitching, or grout-injection techniques in the soil. In addition, surrounding underground pipes—particularly water pipes—must be inspected regularly to monitor their condition and repaired if damaged.

In the face of high winds and the significant damage caused by increasingly large hailstones, strengthening the robustness of the building envelope is the priority. Recommended measures include reinforcing anchoring and fastening systems, replacing conventional glazing with laminated or tempered glass—especially in roofs—and using reinforced shutters.

As with flooding, during storms it is essential to protect mechanical and utility rooms and the sensitive equipment they contain. Particular attention should also be paid to the wind resistance of installed systems: for example, a solar-shading device intended to protect against extreme heat must also be able to withstand high winds.

Like damage caused by drought or flooding, severe weather can seriously weaken buildings and urban infrastructure such as bridges.

Repairs may therefore require structural interventions—such as the use of specific resins or reinforcement systems—as well as replacement of components damaged by impacts.