Londoners find ‘horrendous’ cracks in their homes after successive heat waves
Londoners are facing historic levels of subsidence risk after five successive heat waves dried out the clay soil on which much of the city is built. Insurance claims tied to subsidence hit a record last quarter, with households claiming £20,000 on average.
Intelligence analysis by Llama
Londoners are experiencing historic levels of subsidence risk due to five successive heat waves, with insurance claims reaching a record high. The phenomenon is expected to continue, with subsidence claims making up an ever larger chunk of payouts.
Imagine your house is built on a big sponge that shrinks when it gets dry. That's what's happening in London, where the soil is drying out due to heat waves. This is causing cracks in houses and making it hard for people to live there. It's like a big problem that's getting worse and worse.
Analysis
London's Subsidence Crisis: A Growing Concern for Homeowners and Insurers
Londoners are facing a growing crisis as successive heat waves have led to historic levels of subsidence risk. The phenomenon, associated with hot and dry weather that shrinks the soil and destabilizes foundations, has resulted in a record number of insurance claims. According to data from the Association of British Insurers, households claimed £20,000 on average, a 15% jump from the same period in 2025. The upward trend is expected to continue, with subsidence cases likely to increase due to the hot weather.
The impact of subsidence is not limited to financial losses. It can also devalue a property by an average of 20%-25%, according to the Federation of Master Builders. In some cases, homeowners prefer to cover the cost themselves rather than wade through complicated claims processes. The traditional engineering fix for subsidence damage, known as underpinning, can cost anywhere from £20,000 to more than £100,000.
The phenomenon poses a significant challenge for U.K. home insurers, with subsidence claims making up an ever larger chunk of payouts. Deloitte has warned that U.K. home insurers risk losses in 2026 due in part to the trend. Along with flash floods and wildfires, subsidence is becoming an increasingly material climate-related risk, requiring insurers to display careful consideration in long-term exposure and risk management strategies.
The British Geological Survey estimates that under the RCP 4.5 emissions scenario, 1.8 million properties, or about 5% of the U.K. total, are highly likely or extremely likely to be affected by subsidence. The areas of London most at risk are some of the U.K. capital's most sought-after, namely the boroughs of Westminster, as well as Kensington and Chelsea. While subsidence has been affecting homes in the British capital for decades, climate change is making it worse. London clay is especially sensitive to fluctuations in moisture, expanding when wet and contracting when dry.
Key points
- Londoners are facing historic levels of subsidence risk due to five successive heat waves.
- Insurance claims tied to subsidence hit a record last quarter, with households claiming £20,000 on average.
- The phenomenon is expected to continue, with subsidence claims making up an ever larger chunk of payouts.
- Subsidence can devalue a property by an average of 20%-25%, according to the Federation of Master Builders.
- The traditional engineering fix for subsidence damage, known as underpinning, can cost anywhere from £20,000 to more than £100,000.
If the city can adapt to the changing climate, it may be possible to mitigate the effects of subsidence. This could involve using new materials or techniques to build homes that are more resistant to soil shrinkage. Additionally, the city may be able to implement policies to reduce the impact of heat waves, such as increasing green spaces or using cooling technologies.
The effects of subsidence are likely to worsen in the coming years, with more properties at risk of damage. This could lead to increased costs for homeowners and insurers, as well as a decrease in property values. The city may also struggle to adapt to the changing climate, leading to further problems for residents.
