Homeowners in the United Kingdom are bracing for a surge in subsidence claims, with experts predicting the highest number in more than three decades due to an unprecedented summer of heatwaves and prolonged dry weather. This could lead to tens of thousands of pounds being lost from property values, with some homes at risk of devaluation by up to 25%.
Millions of properties are expected to show new, significant cracks in the coming months. The primary cause is soil drying out during extended dry periods, leading to ground movement beneath homes. Insurers are preparing for a substantial increase in claims, with Aviva's chief executive, Amanda Blanc, already warning that the company may need to increase its reserves to cover the anticipated costs.
Why Claims Are Soaring
Andrew McColl, chairman of the Residential Property Surveyors Association, explained that homes situated on clay soil are particularly vulnerable. During wet winters, clay soil swells, and in hot, dry summers, it shrinks, causing the ground and any structures on it to move. This year's pattern of extreme wet followed by prolonged dryness in many parts of southern England has exacerbated the issue, causing the ground to shrink more rapidly and significantly than usual.
As clay soil loses moisture, it contracts, weakening the support structure of houses and potentially causing them to sink. This movement shifts masonry and brick walls resting on the foundations.
The current situation follows a similarly dry 2025, which also saw a high number of claims. The Association of British Insurers (ABI) reported a record payout of £307 million for subsidence claims last year. This year is being described as a potential 'super event year' for subsidence claims, with soil moisture levels mirroring those of 2025. Insurers are concerned about a potential 'double tap' of high claim volumes, a phenomenon not seen since 1990-1991.
Professionals are already experiencing a backlog of work from last year's dry summer, leading to strains on the repair supply chain. The British Geological Survey has identified millions of homes in areas such as London, Essex, and Kent as being at high risk.
Identifying Subsidence
While new cracks can cause alarm, not all are indicative of subsidence. Key signs to watch for include stiffening windows and doors that have become difficult to open or close, as frames can warp with house movement. Diagonal, step-like cracks are also a common indicator, often appearing wider at the top and narrower at the bottom, frequently seen near bay windows, corners of houses, or around door frames.
The ABI also notes that wallpaper beginning to wrinkle, ripple, or tear without an obvious cause can be a symptom. If a significant crack appears both inside and outside a property, it may signal a more serious structural issue. Subsidence cracks are typically at least the width of a pound coin. Fissures less than two millimeters wide are usually attributed to minor causes like seasonal temperature fluctuations or plaster shrinkage.
Homeowners are advised to note any changes in their home's behavior, such as previously level floors becoming uneven or wallpaper affected by something other than damp starting to wrinkle.
Properties Most At Risk
Properties built on clay soil, common in London, the South East, and East of England, are most vulnerable. Older homes, such as Victorian and Edwardian properties, with shallower foundations are also at increased risk. Extensions and conservatories, which often have less substantial foundations, are particularly susceptible to movement.
Large trees planted near homes on clay-rich soil can also contribute to subsidence. Their roots absorb significant amounts of water, and during dry spells, they can draw moisture from the soil, causing it to shrink and the ground to sink. Older, larger trees, including oak, poplar, elm, horse chestnut, and willow, are typically more problematic than younger saplings.
Insurance Coverage and Repair Process
Most standard home insurance policies include subsidence cover, though a higher excess, potentially £1,000, may apply. Without this cover, repair costs can be substantial. Insurers could face payouts of up to £600 million if this year sees a high volume of claims, comparable to previous 'event years'. Between April and June this year, insurers paid out over £72 million for domestic subsidence claims, with the average claim costing £20,000.
If signs of subsidence are noticed, homeowners should contact their insurer or a surveyor. The process of diagnosis and repair can be lengthy, often taking months or even years. A professional assessment may involve monitoring the property's movement over time, and repair work cannot commence until the root cause is identified. Following completion of repairs, a certification of structural adequacy may be required, which is crucial for selling the property later without a reduction in market value.
Repair costs vary depending on the severity of the subsidence, with complex cases potentially exceeding £100,000. Solutions can range from resin injections to underpinning foundations. However, many issues can be resolved by addressing the underlying cause, such as removing problematic trees. Homeowners are advised to seek professional advice from insurers, tree surgeons, and structural engineers before taking any action, as removing certain trees can sometimes lead to soil swelling and further structural damage.