Check your postcode for London subsidence risk

London’s subsidence timebomb is ticking with new data revealing that the vast majority of the capital’s properties will face significant risk by 2080. Figures from property data intelligence firm Chimnie, published exclusively by the outlet, indicate that without intervention, London could become effectively uninsurable. A market freeze looms.

The rising trend is already apparent in the £307m insurers paid out in subsidence-related claims in 2025 alone, according to the Association of British Insurers.

Risk is highest in the east and south

Currently, the risk is unevenly distributed across the capital. East London faces the highest probability of issues, with 46% of properties currently classified as at probable risk of subsidence. This is followed by southeast London, where the figure sits at 41.9%.

Southwest London holds 36.9%, while west London sits at 30.5%. The remaining areas of the city, including the rest of the eight major postcodes, see risks well below 2.5%.

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Forecast to 2080 and insurer reactions

These current levels are just the baseline. As the Intergovernmental Panel on Climate Change (IPCC) forecasts higher drought rates, the soil will continue to lose moisture. This leads to the clay shrinking and pulling away from the foundations. The situation is poised to worsen significantly in the coming decades.

The capital sits atop a geological layer known as London Clay, which is notoriously unstable when moisture levels fluctuate. Unlike granular soils that compact and stay put, clay acts more like a sponge. When it absorbs water, it swells under the weight of a house; when it dries out, it shrinks, leaving the structure suspended on empty space. This physical behavior creates a perpetual stress test for the housing stock, particularly where older construction methods are involved.

The long-term outlook is stark. By 2050, only the East Central (EC) and West Central (WC) postcodes are projected to keep rates of probable subsidence below 48%.

The fall-off accelerates quickly after that. By 2080, the data from Chimnie suggests that not a single postcode will have risk levels lower than 94%.

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Jonathan Francis, founder of Chimnie, noted the severity of this timeline. ‘The data shows the risk is largely stable to 2030, then erupts between 2050 and 2080, mirroring IPCC projections for UK drought frequency,’ Francis stated. The founder suggests that insurers have a roughly 25-year window before standard coverage for subsidence becomes unavailable.

Insurers are already reacting to localized threats. Colin Herrington, head of claims at Brown and Brown, explained that risk is factored into area ratings. However, the plasticity index of the soil in high-risk postcodes can lead to entire areas being ‘redlined.’ The market reduces for individual homes that have had previous problems with subsidence and many insurance providers may entirely avoid houses with previous claims or repairs.

Potential solutions and future planning

To prevent a total market collapse, experts believe the industry must adapt. Herrington advocates for better collaboration with the British Geological Survey (BGS) to improve predictive capabilities. From a claims perspective, Herrington suggests a shift away from repairing only the specific damage and toward making the whole property more resilient. Non-traditional methods like resin injection will likely play a larger role as the frequency of events increases.

Herrington also pointed to the need for regulatory changes. New build projects may need to incorporate subsidence considerations into their design to prevent adding to the vulnerable housing stock. While the window for action is narrowing, starting these adaptations now remains the most viable path forward.