Losses from flooding remain high in England and Wales in spite of improvements in the management of flood risk and the introduction of new regulations. An important reason is that new homes continue to be built in locations that are prone to flooding: over the last decade more than 120,000 new homes in England and Wales have been built on flood-prone land.

While there have been significant improvements in understanding flood risk trends in England and Wales, there is still a lack of understanding of how changes to the building stock through new developments will be exposed to flooding in the long term, which this paper addresses.

The authors find that new homes built in economically deprived parts of England and Wales between 2008 and 2018 are more likely, compared with new housing in more affluent areas, to become exposed to high flood risk over their lifetime as a result of climate change. This has implications for future spending on flood defences and highlights issues of affordability of private level flood protection as well as flood insurance in the face of climate change.

Key points for decision-makers

  • Flood risk is determined by the nature of the hazard, exposure and vulnerability. To determine the level of risk therefore requires understanding of changes and trends in different flood hazards, factors such as location, design and building characteristics that influence current and future exposure levels, and drivers of vulnerability including deprivation levels and government policy.
  • The authors investigate where new homes have been built over the last decade; how they are contributing to the current and future flood risk of their neighbourhoods; and how the socioeconomic development of the neighbourhoods in which they have been built might affect their long-term flood resilience under changing flood hazards as a result of climate change.
  • Annual building rates of new homes in flood-risk areas in England and Wales have increased only moderately when looking at the national average. However, significant differences between and within regions as well as between different flood types exist.
  • When considering today’s flood hazards the authors find that 5% of all buildings built between 2008 and 2018 are located in high-to-medium flood risk zones (HFR – those that have a 1% or higher annual chance of flooding from river and surface water and a 0.5% or higher annual chance of flooding from the sea). Another 10% of new homes are located in low flood risk areas (LFR – between a 1% [0.5% for sea] and 0.1% annual chance of being flooded).
  • Surface water flooding poses a particular problem: the majority of the 62,413 homes in HFRs are affected by river (42%) or surface water flooding (41%). This type of flooding has only recently been considered alongside other flood types but mapping of this hazard is improving.
  • There are high numbers of new-build homes in HFRs in parts of London and in the Thames Valley for current hazard levels. Other clusters include urban areas in estuaries such as in Liverpool, Hull and Bristol and smaller areas along rivers in the East Midlands and Yorkshire and the Humber.
  • The authors also analyse future flood risk levels under three different climate change scenarios (as used by the UK Committee on Climate Change). They find that without further action the share of homes built between 2008 and 2018 that will be at high risk by the 2050s is expected to significantly increase under a 2°C warming scenario, from 5% currently to 8%, and could almost triple to 14% under a high-end warming scenario.
  • New hotspots are also expected to emerge without further intervention, especially along lower-lying coastal areas in SE England, along the Thames in London and along the Ouse in Yorkshire and the Humber.
  • The spatial shift in flood risk areas as a result of climate change is expected to disproportionately impact homes in deprived areas, notably in multicultural urban neighbourhoods and areas dominated by increasingly struggling home-owners.
  • The authors also look at the implications of new-build for flood insurance, which is currently the key financial protection for homeowners. Under the current Flood Re subsidy scheme new homes built after 2009 are not guaranteed affordable insurance based on the expectation that new buildings should not be at high risk. The paper discusses that flood insurance could become unaffordable or unavailable in several of the deprived areas.
  • Finally, the authors show that flood risk needs to be considered at neighbourhood and community level, even if only a few individual homes currently appear at high risk: boundaries between risk areas can shift, and flood events can trigger property value loss beyond those properties directly affected. This could lead to sudden out-migration or an increase in mortgage defaults and foreclosures after flood events.
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