London’s historic buildings face growing structural threat as summers get hotter

London is facing historically high levels of subsidence risk after five consecutive heatwaves dried out the clay soil on which much of the city is built.

Insurance claims linked to subsidence — a phenomenon in which prolonged hot and dry conditions cause downward sinking of the ground beneath a building's foundations, putting additional stress on walls and resulting in cracks and serious structural damage - reached a record level last quarter, according to data from the Association of British Insurers (ABI), as cited by Bloomberg.

Households claimed an average of £20,000 for subsidence-related damage, the highest quarterly average on record and 15% higher than during the same period in 2025, the ABI said.

Laura Hughes, head of general insurance at the ABI, said the trend was likely to continue.

“We expect to see more subsidence cases because of the hot weather,” she said in an interview.

London residents have taken to social media to describe the impact of subsidence on their homes. Homeowners reported “horrendous cracking” in their properties and doors via social media posts, becoming difficult to open as buildings shifted. One resident described it as “genuinely scary” to discover that their kitchen had moved as the foundations of the house shifted. Another user recounted contacting a structural engineer for assistance.

“Before I could finish explaining he laughed and said, ‘You and 20,000 other people in southeast London’,” the homeowner wrote.

“It’s crazy, what’s happening now,” said Otso Lahtinen, chief executive of Geobear, an engineering company that specialises in repairing subsidence damage. “It’s the new norm, and it seems it will happen more often in the next 20-30 years.”

Data shows that some of the capital’s most sought-after areas are also among those most exposed to subsidence, including Westminster and Kensington and Chelsea.

Global warming accelerating demise

Subsidence has affected London properties for decades, but climate change is intensifying the problem. The risk of subsidence in the UK is concentrated in and around London and parts of southeast England.

London’s clay soil is particularly sensitive to changes in moisture. It expands when wet and contracts when dry, meaning increasingly hot and dry periods can cause the ground to shrink beneath buildings.

In the four years to 2025, insurance payouts for subsidence damage increased by around 90% to a record £297 million (approx. $402 million), according to ABI data.

The properties most vulnerable to the problem are Victorian and Edwardian homes built directly on the upper layers of London clay. Modern office buildings in areas such as the City of London and Canary Wharf are generally less exposed because they typically have much deeper foundations.

In recent months, extreme temperatures have forced schools to close, contributed to bus driver strikes and prompted some banks to relax office attendance requirements to protect employees from excessively hot commutes. Much of England has also been affected by drought, while hospitals have come under increasing pressure during periods of extreme heat.

London Mayor Sadiq Khan has warned that the capital will need to attract private investment to help pay for the costs of adapting to rising temperatures. His office estimates that London could face an annual bill of up to £36 billion (approx. $49 billion) through the 2050s to prepare the city for the impacts of climate change.

By Nazrin Sadigova