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By Gautam Naik
It’s increasingly
clear that the summer of 2025 left deep scars on
some of London’s most sought-after homes.
After a year
of record-breaking heat, owners of homes across
the UK capital have been witnessing a sudden
rise in cracked walls, warped door frames,
and sloping floors. The phenomenon driving such
occurrences — known as subsidence — is
associated with bouts of hot, dry weather that
shrink the soil and destabilize the foundations
on which properties stand.
A crack in
Barbara Richardson’s living room. Photographer:
Carlotta Cardana
Those studying the
development closely estimate that well over a
million London properties will be at risk of
subsidence by 2030 as temperatures rise. Data compiled by Aviva
Plc suggests that subsidence has the potential
to affect most of greater London. High-end
boroughs such as Kensington and Chelsea, where
homes can cost several million pounds, are among
those most at risk.
Subsidence
is nothing new, but the intensity with which
it’s affecting London is now on the rise. The
city’s vulnerability stems from its clay-rich
soil, thirsty trees, and the many Victorian and
Edwardian-era homes built on shallow
foundations. Those risks are now being
exacerbated by global warming, according to the British Geological
Survey.
For homeowners, the
development is proving deeply unnerving.
Barbara Richardson,
the owner of a £1.7 million ($2.3 million) house
in the London neighborhood of Dulwich, says “the
cracks appeared suddenly.”
Richardson says she
first spotted a large split in her living room
wall after the end of summer, in September.
“I lay in bed
thinking that the house was going to fall down,”
she says.
Louise Clark,
manager of general insurance policy at the
Association of British Insurers, says the
threats posed by subsidence are becoming “more
acute as climate change worsens.” The
association estimates that insurance claims tied
to damage done by subsidence hit a record in
2025.
In the first half
of 2025, total UK insurance claims for
subsidence rose 23% to £153 million compared to
the year-earlier period, according to the
Association of British Insurers.
Meanwhile, Axa notes that subsidence issues have
the potential to wipe 20% off a
home’s value.
In the past two
decades, there have been about six so-called
subsidence surge years in Britain, of which 2025
was one. At the same time, the cost of tackling
the issue has been rising steadily. Even in
2024, which statistically didn’t qualify as a
surge year, UK insurers covered twice as many
subsidence claims as they did six years earlier,
with the average payout nearly doubling to
£15,100. In the summer of 2025, the average
payout exceeded £17,000.
In recent years,
extreme weather conditions have helped
destabilize the foundations on which London’s
properties sit. In 2022, an exceptionally dry
summer led to nearly 3 millimeters of ground
sinkage in some areas, while a particularly wet
winter in early 2024 drove ground levels up by
close to 3 millimeters in parts of greater
London, according to data provided by
Value.Space, an insurance technology company.
The threat to
property values posed by such developments has
spawned a cottage industry of companies offering
engineering remedies to desperate London
homeowners. Many such firms say they’re now
struggling to keep up with demand.
“We are maxed out,”
says Otso Lahtinen, chief executive and majority
owner of Geobear, a UK-based
engineering firm that strengthens foundations
weakened by subsidence.
According to
Lahtinen, rapid growth in Geobear and other
companies targeting subsidence is drawing
considerable investor interest. “We’re
constantly talking to private equity firms,” he
said.
Mainmark Ground
Engineering Ltd., a unit of
Australia-based Mainmark, has also noticed a
sharp increase in demand for its work. It
charges homeowners as much as £35,500 to tackle
subsidence issues threatening a typical
four-bedroom detached house, depending on the
method used.
Alice Morgan, who
owns a £1.5 million home with her husband,
Daniel, in the south London district of
Wandsworth, says that even though their
insurance policy is supposed to cover damage
caused by subsidence, they’re choosing to cover
the cost themselves, in part after struggling to
get previous claims covered.
To fix their house,
they’ve now hired Geobear at a cost of £15,000.
A Geobear
team at work on an Edwardian-era home Photographer:
Carlotta Cardana
Those affected by
subsidence generally don’t want to talk about
it, Alice says. It’s “a dirty secret that people
feel ashamed to admit,” she said. “It’s like
having rats.”
Read the full
piece to hear other homeowners’
stories. This is the fourth story in Disaster
Industrial Complex, a series that looks at the
business of defending against and rebuilding
from climate disasters and how it increasingly
drives the economy. Read the first, second,
and third story.
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