London Homeowners are being urged to stay alert for symptoms of subsidence, as temperatures are predicted to surpass 27 degrees Celsius in the wake of the UK’s ‘Indian Summer’ this week.

Forecasters have suggested that parts of the UK will reach nearly 30 degrees in September in the Southeast of England, with the hottest regions centering around London.

While a welcome break from the drizzle for many in the capital, news of the mini heatwave comes just a few weeks after the London Climate Resilience Review estimated that 40 per cent of London homes are likely to be affected by subsidence by 2030.

Now, ground engineering experts are warning residents that excessive drying of the clay soil in London’s foundations could lead to structural damage for homes across the Capital. During sporadic periods of heat, this makes homes more susceptible to damage and could ultimately impact the value of your home.

What is subsidence?
Subsidence occurs when the ground beneath a building sinks, causing unstable foundations, damage to homes, and compromising a structure’s safety.

Homeowners looking to sell could risk losing 20 per cent of their property’s value if severe subsidence is found according to Open Property Group which, in a volatile housing market, could result in a significant financial loss to the seller.

At a time when mortgage rates remain at the highest level for 16 years, homebuyers and those remortgaging already must pay a lot more than they would have had to a few years ago.
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So, to prevent further financial losses for homeowners looking to sell, subsidence expert Mainmark Ground Engineering (UK) is advising homeowners take an ‘improve before you move’ approach when selling your home.

Freya Chapman, Residential Lead at Mainmark, said: “With the UK’s continued changing weather patterns – with more wet and warm summers predicted – we all need to consider the wider impact, especially on our homes. Periods of extreme heat can for example also lead to subsidence, a problem which effects around 40,000 properties a year.

“In the UK alone, an estimated 6.64 million properties will be at medium to high risk of subsidence by 2030. This puts you at a higher risk of flooding during rainy periods and affects property value. Homeowners are also likely to see their insurance premiums increase as subsidence-related insurance claims peak to a whopping £1.9bn.

“While it can take many years for it to show any effects on structures, it’s best dealt with as early as possible to minimise the work that must be carried out during the repairs.”

What are the symptoms of subsidence?
The most common sign of subsidence is cracks appearing in the walls, naturally weakening a property’s structure.

While small cracks could be simply cosmetic (usually common in properties more than 30 years old), indicators of subsidence will be cracks wider than five millimetres, a difference in the height of the two sides of the wall, or cracks following a stepped or zigzag pattern. Water stains can also be an indicator of a crack in the outer wall letting rain into your property.

Weaker points of a structure – for example, where you have a door or window – are more prone to the early signs of subsidence. This might cause gaps to appear around the frames, or the frequent jamming/sticking of your windows and doors.

Older properties, which may not have the same quality or depth of foundation, are also susceptible. If you’re a homeowner of an older property, who is looking to sell, it’s also best to get a professional opinion on your groundworks to ensure you don’t lose value in the future.

Sinking floors are the most obvious signs of subsidence in your home. Often this is concentrated to the middle of the property or in a corner, where the ground slopes in either a ‘dish’ shape or floorboards start to pull away from the skirting boards.

If any of these symptoms are occurring in your home, you may need to look for ways to strengthen and re-level your foundations.
Non-invasive ‘keyhole’ surgery
Thanks to advances in technology, subsidence can be fixed in one day using methods like keyhole surgery. Long-gone are the days of costly, resource-intensive and disruptive renovation works, which take days or weeks to complete.

Resin injection is a non-invasive technology, whereby resin is injected into the soil below the foundations to reinforce the ground. For a homeowner, this has many benefits: it is efficient and more economical than tradition concrete underpinning, which may involve you leaving your home for a period of time while work is carried out.

The resins are an environmentally inert alternative to energy-intensive ground excavations. It’s a straightforward and cost-effective process, and will save homeowners a lot of time, money and hassle long-term.

Mainmark Ground Engineering (UK) Ltd is a subsidiary of the Mainmark group of companies established in 2016. The company, located in Milton Keynes, has extended its UK offering of 15 per cent off the full price of a subsidence survey for residential jobs up until the end of August 2024.

For over three decades, Mainmark has established itself as a pioneering force in the industry, leading the way in developing and delivering cutting-edge solutions. Mainmark has earned international recognition as an award-winning ground engineering organisation.