In the southwest, houses cracked by clay soils

“In thirty-four years, the crack had not moved,” says Annie, in front of the wall of her house in Castelmoron-sur-Lot (Lot-et-Garonne). But the overwhelming heat of this summer was right for the small stone facade.

One morning in August, while the retired nurse goes around her garden, she discovers on her wall a lezarde several centimeters wide. The crack crosses the room it arranged to welcome her family. “I am afraid that the wall falls into the slope,” she breathes, anxious.

Castelmoron-sur-Lot was suffocated during the heat wave that hit France in August: up to 42 ° C. In clay soils, the earth, first swollen by increasingly strong rains, has retracted with drought. So, on these moving terrains, the houses have tanned and cracking. The southwest, which combines repeated droughts and sensitive soils, is one of the regions most exposed to this remoncing of clays (RGA).

“At night, before falling asleep, I hear the crackles. It’s a bit scary, ”admits Sylvie, who lives below in the village. Above her, a crack crosses the outer facade of her house. With her husband, they bought this pavilion built in the 1980s five years ago to live their retirement. “These light individual houses, with shallow and underground foundations, typical of recent decades, are the most fragile,” explains Valentin atAubernard, an expert in building pathology.

11 million houses in France concerned

The first cracks appeared at the end of winter, while drought already settled. Patrick and Sylvie share their concern with the deputy mayor, who came to the damage: the aggravation can be fast and repairs cost an average of 15,000 euros. They are far from an isolated case.

About 11 million houses in France are affected. And this figure could increase to 16 million in 2050, if the scorching episodes continue to fall with the same intensity.

A precedent in 2022

In Castelmoron, the town hall is preparing a request for recognition of the state of natural disaster so that the victims are compensated. “Afterwards, it is the state that decides,” said the assistant, Jean-Claude Vigneau, with a resigned air. The mayor, Line Lalorie, knows something about it: “After the drought of 2022, we did not obtain recognition by the State.”

Sitting at her office, she reads the ministry’s response aloud: “The meteorological criterion set by the circular … is not fulfilled.” The appeal filed by Castelmoron and 27 municipalities in the department has not succeeded. From this Kafkaesian maze remains a strong feeling of injustice: “All the neighboring municipalities have been recognized.” Result: the majority of the fifty homes affected in 2022 could not initiate the necessary work. “This year, we start again!” , she said with determination.

The cost of claims explodes

Even in the event of recognition, compensation is an obstacle course. Expert battles to establish the link between cracks and RGA are frequent. In reality, the State – which supports half of the compensation linked to natural disasters – and insurers are reluctant to open the boxes too largely.

Because since 2016, expenses have exploded. An increase that should continue: between 2020 and 2050, the cumulative cost of the RGA would reach 43 billion euros, three times more than between 1989 and 2019. To limit breakage, prevention appears to be the main hope. Some solutions already exist: erect a sidewalk around the house so that the sun does not hit directly on the floors and does not dry the earth too close to the walls; Rehumidify them from the inside via membranes that are buried; Monitor water flows and surrounding vegetation. You still have to be informed

“The vast majority of municipalities are not at all prepared at all,” deplores the deputy Vincent Ledoux, author of a report on the subject in 2023. He hopes that the municipal elections of 2026 will arouse a start: “Mayors must accompany the inhabitants, who are often not aware of the risk when they buy.”

Martine, who contemplates the village from her garden, on the hillsides, too is looking for a remedy for the multiple cracks that have been appeared for four years on her house. In the meantime, it holds paper to avoid drafts. She wants to preserve this little corner of paradise, so that her eight grandchildren continue to brighten up her summers.

* The first names have been changed