Properties in ‘Geohazard Hotspot’ West Sussex Could Face Costly Subsidence Threat

New data from the British Geological Survey (BGS) has identified West Sussex as a geohazard hotspot, ranking it alongside Devon, Dorset and Hampshire as one of the UK’s most vulnerable regions.

According to the report, a range of underlying geological conditions and processes are driving these risks, most of which are linked to ground movement. This instability poses a growing threat to properties and infrastructure across the region, with the potential for costly damage if left unaddressed.

Subsidence is one of the most underestimated and costly risks that property owners should be aware of. While British businesses and many homeowners may not be strangers to the sub-structural issue, few are aware that delaying the reporting of subsidence can result in increased repair costs, considerable disruptions to operations and even irreversible damage, making properties unsafe.

The news from BGS comes as figures released by the Association of British Insurers (ABI) show thousands of claims relating to ground movements are made every year, costing millions to remediate. Homeowners and businesses could face financial pressure if repairs are prolonged, adding to the overall cost of restoration.

Subsidence, the gradual sinking or shifting of the ground, can cause cracks in walls and floors, collapsing foundations, making surfaces uneven and compromising structural integrity. When left untreated, its effects only worsen, often leading to more expensive repairs and in severe cases the partial or total collapse of the properties and structures.

Unfortunately, across both residential and commercial spaces like warehouses and office blocks, subsidence issues aren’t reported until it’s too late. This often results in higher repair costs and often significant disruptions to daily operations or leaving occupants needing temporary accommodation in the case of housing.

Adam Fleet, Technical Sales Engineer at Ground Engineering firm Mainmark UK is urging property owners to take a proactive stance on subsidence early detection and reporting to control remediation costs.

“If caught early, initial subsidence is a quick fix. It is resolved using non-disruptive methods such as resin injection technology. However, if the issue is ignored, the same case may require a more complex solution, such as underpinning, at a far higher price within just a few years.

“Delaying intervention doesn’t just increase the direct cost of repairs, it’s knock-on effect can also lead to business disruption in warehouses, unsafe conditions for workers and lost revenue/decreased value for landlords. Businesses and property owners want to avoid extra costs for repairs due to subsidence risk being overlooked.”

Mainmark has worked on several projects in the region, including the filling of voids beneath a subsiding footway outside retail units in a Retail Park in Chichester. Voids beneath the footway had caused it to sink directly outside the shops, creating a trip hazard. Approximately 150 linear metres of footway was treated with the firm’s Teretek® Resin Injection to fill voids, provide support and allow resurfacing works to commence.

Adam continues: “Regular subsidence assessments must be a priority, especially in areas deemed such a high risk geohazard hotspot, and while the initial inspection costs may seem high, they pale in comparison to the financial consequences of delayed repairs. Raising awareness of subsidence indicators across various settings is crucial to enabling prompt intervention.  Cracks in walls, uneven floors, doors and windows sticking, sagging or sinking foundations, and persistent pooling water are all early warning signs of ground movement that should be addressed without delay.”

The message is simple: subsidence is an issue that should never be ignored or left unchecked until it’s too late. While reporting subsidence issues early might appear as an extra expense, it’s the best step towards safeguarding commercial properties and minimising future costs. The urgency of this issue must be recognised, and proactive steps must be taken to address subsidence before it escalates.