While much of the UK experiences exceptionally high temperatures, prolonged periods of hot and dry weather could increase the risk of subsidence to homes and businesses.
Heatwaves in the UK and Europe have been occurring more frequently and with greater intensity in recent years, with many scientists attributing this to climate change. The UK’s Met Office National Climate Information Centre has stated climate statistics over time reveal an “undeniable warming trend for the UK” and that climate change is making heatwaves more likely.1
Heatwaves in the UK and Europe have been occurring more frequently and with greater intensity in recent years.
Subsidence, where the ground beneath a property loses moisture and sinks, can be caused or made worse by a variety of factors, such as prolonged dry spells, geology, the presence of trees, or the affected building’s characteristics.
The last significant heatwave event in the UK in Summer 2018 featured the highest level of subsidence claims since the 2006 and 2003 heatwaves, according to the Association of British Insurers (ABI). Over 10,000 households made claims worth £64 million during this period, up from £14 million—a 350 per cent increase year over year.2 More recent heatwaves in 2020 and 2021 also featured substantial claim volumes but not as high as 2018.
From an insurance perspective, understanding how a property is vulnerable to subsidence, heave, and other types of risk associated with ground movement is essential for accurate rating and evaluating true loss exposures.
A growing problem
Houses that are built on shrink-swell clay soil are the most likely to claim for subsidence damage, with over 70 percent of domestic subsidence claims estimated to be from clay shrinkage.
Large areas of clay and shale can be found in England and Wales and are examples of where properties could be more susceptible to shrinking and swelling. Many cases of subsidence are reported across a particularly large band of clay known as London Clay, which affects much of London, Essex, and Kent. While many properties that are situated on areas of shrink-swell clays are typically more exposed to subsidence and heave, factors such as rainfall, vegetation, property characteristics and historical claims must also be considered so insurers aren’t overestimating the risk or taking on a risk where they’re underestimating a property’s true exposure.
Last year, the British Geological Survey (BGS) warned that climate change is causing the area of properties susceptible to subsidence in Great Britain to expand significantly, rising from 3% in 1990 to 6.5% in 2030 and 10.9% in 2070. In areas of London, this figure is expected to rise from 20.1% in 1990 to 43% in 2030 and 57.3% in 2070.3
Research from LV= General Insurance in 2021 also found that subsidence claims are becoming more frequent, with larger claims costing around £30,000 and some in excess of £500,000.4 With the increasing frequency of claims – which could increase in size subject to labour, material, and rebuild costs – subsidence could pose a huge challenge to insurers in the future.
Quantifying subsidence risk with Verisk
Understanding a property’s vulnerabilities and the likelihood of a claim is an integral part of accurately rating subsidence, heave, and other types of risk associated with ground movement.
Verisk’s Subsidence Insight, part of the Perils Insight suite of data models and available at postcode or address level, uses the latest property data — together with detailed vegetation and tree data, geology, long-term climate data, and claims history — to model the level of subsidence, heave, and other ground movement risk for insurers. It’s the unique interaction of these variables that helps insurers more accurately rate such perils. Subsidence Insight is also available in real-time via our Data Insight Hub for delivery at the point of quote.
With climate change potentially making claim volumes in the future more volatile, it will be critical for insurers to use mapping technologies and external data models to better understand their exposure to a worst-case scenario.