Monitoring buildings from space – a subsidence breakthrough

January 11, 2023

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Subsidence claims can be expensive and time consuming to manage, often taking up to a year or more to resolve. However, the ability to track building geometry from space is edging closer, and this will mean insurers and claims management companies can collect reliable historical and current property movement data more quickly, easily and cheaply.

Climate change

The Met Office projects that future summers in England will be longer and drier due to climate change. Last summer, the UK’s warmest on record, is a good case in point. And prolonged periods of warm, dry weather will inevitably drive an increase in subsidence claims. 

However, while this year has been declared a subsidence surge year, claims numbers were nowhere near those of 2003 and 2006. This is because the local authorities and general public awareness around managing trees and vegetation – particularly those that notoriously desiccate the ground, such as plane, willow and oak – located close to properties has improved in recent years. And this has undeniably helped mitigate claim numbers. 

Subsidence surge – the cause

There are various reasons why the ground might move below the foundations of a building, but in a subsidence surge, most claims involve properties located in clay soil areas where mature trees are growing close to the property. 

In complex cases, site investigations are required to identify the soil type, the roots beneath the foundations of the building, and any evidence of the soil drying. And the correlation of all these things, specifically to the property damage, will confirm the cause. 

If it’s found to be due to the proximity of a tree, and the tree in question belongs to a local authority or is protected by a tree preservation order, at least 8-12 months of labour-intensive ground monitoring will be required before a decision to remove the tree can be taken. 

While this might not be a popular outcome, in our experience, even aggressive pruning rarely works as it stimulates further tree growth. Felling the tree is, in fact, kinder to the environment compared to the remedial works that might otherwise be required for the building – such as underpinning, ground stabilisation using geopolymer cement or installation of a tree root barrier. 

We also support a carbon offset programme where for every tree we remove, another is planted in a more suitable location to counteract the environmental impact. 

Subsidence – the future

In August 2022, volumes of subsidence claims increased by nearly 500%, with surge conditions continuing for 17 weeks, and it’s estimated that around 21,000 claims were received across the industry. In surge events, 75% of claims reported are usually valid, whereas in a typical year, this figure is more likely to be 50%, and the average cost of claims also increases by around 14% as the damage tends to be more widespread. 

As subsidence looks set to become an ongoing problem, it’s crucial that we find faster and more cost-efficient ways of handling this type of work.

Sedgwick recently participated in a pilot, providing sample subsidence claims data to help calibrate a new satellite tracking service. The initial results show an excellent agreement with ground-based monitoring evidence — indicating that the practical application of this technology could improve service delivery and save insurers substantial sums in resolving subsidence claims.

Satellite monitoring

While satellite monitoring of subsidence claims is new to the insurance market, the technology is already routinely used in a wide range of scenarios – to monitor the stability of entire rail networks, for example. 

Using sequences of satellite radar images, this service can measure the movement of ground locations with millimetric accuracy. The historical data it collects can show how long subsidence has occurred and whether there’s continued movement on almost any individual address. And you don’t need people or instruments on the ground.

Submitted subsidence claims can then be immediately supported with reliable evidence that justifies previous and ongoing movement in the building. This information might otherwise take at least one year to collect using traditional ground monitoring methods. 

There’s still some way to go in validating the information gained by satellite monitoring, and local authority acceptance that the data is well-founded will be key to its future success. But this could be a huge breakthrough that will potentially transform how subsidence claims are handled in the future.

Tags: building, Claims management, climate, climate change, Data, environmental, Environmental impact, Property, Technological advances, Technology, UK, United Kingdom