Understanding the risk of flooding on the UK’s housing market

The UK Sustainable Investment and Finance Association’s (UK SIF) report with Public First Flooding the Market: The Climate Mortgage Trap highlights a growing and underappreciated financial risk: the UK mortgage market is increasingly exposed to climate-driven flood risk which is not adequately reflected in adaptation practices, mortgage lending, property valuation or housing policy.

Key findings

The report shows that flood risk is materially underestimated across the housing and mortgage market. Large numbers of homes at high or increasing risk of flooding continue to be built, sold and mortgaged, often without adequate flood protection, disclosure or long-term risk pricing. As climate change accelerates, properties that appear affordable and insurable today may become uninsurable, unmortgageable or significantly devalued over the life of a typical mortgage. This is particularly concerning given that risk assessments often rely on backward-looking data, insurance availability today or assumptions that public flood defences will scale fast enough to offset rising exposure.

The report warns that lenders, investors and policymakers are collectively locked into a short-term risk horizon, while mortgages routinely extend 25–35 years into a future with higher sea levels, more intense rainfall and overstretched flood defences. The result is growing misalignment between climate reality and financial decision-making.

The report also highlights distributional impacts: lower-income households are more likely to be exposed to flood-prone areas and have fewer resources to adapt, retrofit or absorb losses. Without action, climate risk could widen existing inequalities in home ownership and wealth.

What this means for the wider economy

At a system level, mispriced flood risk poses a financial stability concern. A sharp correction in property values in high-risk areas could affect banks’ balance sheets, mortgage-backed securities, insurers and pension funds showing that this is not just a housing issue but a macroeconomic one too.

UK SIF argues that avoiding a “climate mortgage trap” will require:

• Stronger building and planning regulations to embed flood resilience in new developments

• Integration of forward-looking climate data into property lending and valuation

• Better alignment between housing policy, planning, flood defence and financing

Without coordinated action, the UK risks locking households and financial institutions into assets that climate change will negatively impact, running the risk of today’s mortgages becoming stranded assets in the future.

If you’d like to find out more about physical climate risk and its financial impact, get in touch.