Paul Dunne
By Paul Dunne, Partner in Building Consultancy at Rapleys.
With the mercury rising to an all-time record in England of 40.3 degrees in 2022, and flash flooding regular (gone are the memories of the 100-year storm – in fact, we are running out of names for them so frequent they are), it should come as little surprise that our buildings are struggling to last.
In the last 12 months to August, subsidence payouts totalled £54m, up by 21% compared with the same period in 2022, according to the Association of British Insurers (ABI), while home insurance premiums have rocketed following storms and flooding leading the ABI to call for building regulations that make homes more resilient to such climate change challenges.
Subsidence is a structural problem caused by the foundations of a house – or other type of property – sinking into the subsoil. This can be triggered by water leaks, drought, tree roots and so on. Early signs are cracks in the walls, misalignment of doors and windows but the reality is that if left, the structural integrity of the building can be compromised and can cause partial (or total) collapse. It can be fixed, but it is very expensive – hence the rise in insurance payouts.
With longer, hotter drier summers in the UK, soil shrinkage is cited as the main reason behind this increase. Claims are likely to get worse as the soil conditions continue to change over time.Throw into the mix flooding, which in itself causes £700m of damage per year, and we have a perfect storm of conditions that ultimately can lead to subsidence.
But how can we protect our buildings from the weather?
The short answer is we can’t effectively right now as subsidence measures are largely reactionary. But, there are some simple things we can all do to reduce the risk. Trees remove large volumes of water from the soil so removing trees or bushes that are planted near housing and replanting elsewhere could help – although each instance would need to be reviewed on its specific merits. Otherwise, inspecting the exterior of properties paying particular attention to pipework, gutters and draining systems in case of leaks and blockages is another pre-emptive measure.
Soils that are largely cohesive like clay and silt are most likely to contribute to subsidence as they shrink and swell depending on moisture, thus hugely impacted by the weather. By understanding the soil composition around housing or on sites can help in prevention.
If subsidence is threatening the structure of a property, then the main fix is underpinning, which is expensive – hence the insurance pay outs.
With the climate getting more extreme, it’s about time that this was factored into new developments and planning consents. Soil remediation for example should be a requisite for development on sites or locations with high clay content. Planting should be guided with rules about how close to the proposed structures they can be.
Increasing subsidence is just one example of the impact of climate change on our buildings and, like subsidence, ‘future proofing’ is not always possible and could be too late. Modern foundations can be designed to accommodate these anticipated and actual new levels of movement but the existing stock will be equipped with foundations that were the typical practice of the time, through the decades, that are less likely to be equipped for the more extreme conditions now being experienced where the soil conditions may cause issues.
The built environment deserves to last and so we must think earlier about planning for the weather. If that means another look at building regulations for the long-term, so be it.
