This year’s heatwave will exacerbate the problem of clay soil contracting; Leslie and Margaret Owen in Saône-et-Loire are still fighting insurers over drought cracks that appeared in 2020 Pic: Alamy Banque D'Images / Leslie and Margaret Owen

Thousands more houses in France are expected to be left with sizeable structural cracks after this summer’s early heatwaves as they are built on clay soil which contracts during droughts.

More than 10 million homes across the country are at risk after the official map of affected zones was enlarged last year. 

However it is difficult for homeowners to claim for damage as this requires the commune to be declared a catastrophe naturelle (natural disaster) zone by the state – but often the damage does not appear until months, or even years, after.

Many have to fight for years for repairs.

Almost half (48%) of land in France is now deemed at risk, including all along the Mediterranean coast. Detached houses are particularly affected.

This year’s heatwaves – and climate change in general – are exacerbating the problem, with droughts causing the soil to contract and cause subsidence and building foundations to shift, leaving significant structural cracks.

Read more: Vehicles, homes: claiming compensation for weather damage in France

A recent report from government research body Cerema said: “The increasing frequency of extreme droughts observed over the last six years will make buildings more vulnerable and have a cumulative effect on damages, which will require more expensive repairs.” 

Insurance federation France Assureurs estimates the cost of drought damage will total €43billion between 2020 and 2050, triple the amount of the previous 30 years.

Read more: Drought map update: See the French departments with water restrictions

A catastrophe naturelle declaration to open up insurance claims has to be published in France’s Journal Officiel, giving those affected a few weeks to apply.  

It is used for floods and other natural damage but is ill-suited to subsidence claims because of the length of time it can take for signs to appear.

One homeowner told The Connexion that she noticed cracks in her home in the Ain department following a long dry spell in 2018 and is still awaiting a solution.

Hélène Niktas said: “The outside wall had a centimetre-wide crack, a door no longer closed, an unpainted part of the ceiling was exposed from where the wall had moved.

“I didn’t immediately notice that air was coming in because it was August but by November, cold air started coming through a small crack, so I had to fill it. 

“This required opening it slightly so I could put the product in, and that’s when I noticed the masonry was damaged.” 

Rather than strengthening the foundations to protect the structure in the future, her insurer only suggested repairing the cracks. 

So she took the case to court, where it awaits an outcome. “I still haven’t had any repairs to date,” she said.

Efforts led by the Charente senator Nicole Bonnefoy to have the system of insurance claims for this reformed were not adopted by the government.

“As far as we can tell, there is nothing happening at the moment,” said a spokesman for Senator Bonnefoy. 

“All the momentum built up under previous Macron governments has been lost and it no longer seems to be a priority.”

New building regulations have been in place since 2020 to ensure new-builds are stronger and more able to resist clay movements. Half of the homes affected were built post-1976.

Key to the new standards is having the soil on building plots analysed for clay before work begins, and where it is present, having deeper, larger and stronger foundations.

‘Shrink-swell’ mainly affects detached houses, as apartment blocks generally have deeper foundations. 

Old homes, especially stone buildings with wide walls, also cope better than modern ones which are built out of concrete blocks.

Talks between insurers and the government were interrupted by the elections and are likely to resume in the autumn.

During earlier discussions, insurers wanted to change the rules so only the structural cracks would fall under natural disaster rules.

Ms Niktas, who now volunteers with Les Oubliés de la canicule, an association which guides victims through drought insurance claims, said the biggest problem was firms refusing to pay for durable, structural repairs over short-term fixes.

“They prefer to refuse claims as they know most people don’t have the time, courage, or the money to pay for a lawyer and take them to court.”

She accused insurers of sounding the alarm about droughts so they would be removed from the catastrophe naturelle regime and homeowners would have yet another policy to pay for.

While waiting for new talks, insurers have given their full backing to an experimental technique called MACH (Maison Confortée par Humidification) developed by Cerema which could be approved in the next year or two. 

It was tested between 2016 and 2020 on a house with cracks and involved collecting rainwater in tanks, and then releasing it through pipes near the foundations when sensors in the soil showed the clay was drying out. 

Existing cracks in the house did not get any bigger and no new ones developed.

Cerema says installing a MACH system will probably cost €15,000, compared to €16,300 for the average cost of traditional repair systems.

Factors other than drought, such as problems with drains, the pumping of underground water, planting trees or waterproofing of areas around buildings, can also cause clay soils to swell or shrink and crack houses but are not usually covered by catastrophe naturelle insurance.

Leslie Owen and his wife Margaret are still fighting to get their insurance provider to cover repairs to cracks which appeared in their farmhouse in Saône-et-Loire in 2020. 

Over the summer the couple, who moved from the UK in 2013, spotted several cracks in the stone walls and along the floor. 

“The wall has also moved relative to the timber beam built into it. If it keeps going the wall will collapse,” said Mr Owen, a former architect. 

The insurer claimed this was not a result of the drought but the Owens hired an expert to dispute this and are waiting to find out the cost of repairs. 

“In my naïveté I thought I had an all-risks insurance policy,” Mr Owen said.

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