Subsidence, the downward movement of the ground beneath a building, can cause a structure's foundations to sink. And this risk is accelerating.
In fact, subsidence-related insurance claims reached £153 million in the first half of 2025 alone, providing nearly 9,000 households with an average payout of £17,264 per claim1.
The evidence is quite clear: subsidence is no longer confined to older buildings or specific locations. It's a portfolio-wide risk that can affect any property you live in or manage — residential, commercial or mixed-use.
Reason for change
The fundamental driver behind this surge is climate change, translating directly into heightened geo-risk. The primary cause of subsidence in the UK is the climatic influence on clay-rich soils, particularly prevalent through the country. This is attributed to the reactive nature of these soils: they expand when saturated and contract aggressively when dry.
Soil moisture deficit levels recorded in July and August 2025 mirror those seen during previous high-impact years in 2018 and 20222. Subsidence claims have gone up following hot, dry summers, with damage typically becoming apparent only after consistent rain returns. This pattern is intensifying.
Climate projections point towards the UK experiencing more frequent periods of drought and heavy rainfall, creating a cycle of shrinkage and expansion, applying increasing pressure on building foundations.
The British Geological Survey (BGS) has identified subsidence hazards resulting from shrink-swell clay soils, inadequate foundation structures and tree proximity as leading causes of financial loss for property owners and managers2. For professionals overseeing multiple properties, these costs reach well beyond simple repairs, leading to higher insurance premiums, lower property values and, in severe cases, major engineering works that disrupt residents and place pressure on service charge budgets.
Who is affected?
While block management and residential freeholders are obvious targets, this risk is now sector-agnostic. Any organisation with an owned or managed property portfolio — from commercial offices and industrial facilities to educational campuses and retail sites — faces exposure. The risk doesn't consider property age, construction type or sector.
Subsidence is beyond just building repair cost; it is a business continuity risk. The operational impact can be substantial: structural repairs often require residents or tenants to relocate temporarily, creating communication challenges and potential complaints. Investigations and monitoring often require months, due to the coordination of specialist surveys and handling of insurance processes.
For block managers, complications can multiply. This includes explaining structural issues to leaseholders, navigating shared ownership responsibilities and managing service charge implications for major works.
Steps to manage and mitigate
- Prioritise drainage stability: Thorough maintenance of gutters, pipes and plumbing can help prevent leaks. Broken drains or leaking pipes can either saturate the soil or wash away the underlying structure, causing instability. Schedule regular drain surveys; this is particularly important in high-risk areas.
- Manage vegetation strategically: Consult a qualified arborist to assess the proximity of large, high-water-demand trees (like oaks or willows). Implement strategic pruning or install root barriers to control moisture extraction from the soil near foundations. Clarity on tree ownership (e.g., local authority vs. freeholder) is essential for liability.
- Implement early detection protocols: Appoint site and maintenance teams to investigate key visual signs. Cracks appearing diagonal, wider than 3 millimetres and visible both inside and out require immediate action. Also, look for sticking doors and windows. Date-stamped photographic evidence is vital.
- Build for resilience: For capital projects or major works in high-risk areas, invest in deeper or reinforced foundations. Consider ground stabilisation techniques to future-proof the asset and minimise long-term maintenance costs.
Why acting now matters
Subsidence claims are expected to become more commonplace as climate-related risks intensify. The combination of record temperatures, changing rainfall patterns and vulnerable soil types creates ongoing exposure across various property portfolios. Intervention is key.
The financial implications can extend beyond immediate repair costs. Properties with subsidence history could face higher insurance premiums, and when you're managing multiple properties, even a modest premium increase can compound quickly. Service charge implications for major structural works can strain leaseholder relationships, whilst reduced property values affect your clients' asset performance.
Reputation matters for property and block managers. The ability to identify risks early, coordinate effective responses and minimise disruption to residents demonstrates the value of professional management. Conversely, failing to spot warning signs or delaying action can lead to more extensive damage, higher costs and unhappy residents and property owners.
More importantly, early action provides options. Detecting movement in its initial stages often involves straightforward solutions, such as resin injection to stabilise soil, rather than extensive underpinning work that requires residents to vacate, often leading services to a standstill for months.
How we can help
Connect with a Gallagher specialist today to get a clear, thorough assessment of your portfolio's subsidence vulnerability and to structure a resilience plan that protects your long-term assets.
