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Glossary

Vulnerability Classification

The categorisation of development types by their sensitivity to flood risk, as defined in Planning Practice Guidance. The classification determines which uses are appropriate in each flood zone.

The vulnerability classification system, defined in the Planning Practice Guidance, categorises all types of development according to their vulnerability to flood risk. This classification is fundamental to the flood risk planning process, as it determines which developments are permitted in each flood zone and whether the Sequential Test and Exception Test are required.

The five classifications are:

  1. Essential infrastructure: Transport infrastructure, utility infrastructure, and water treatment works that must be located in a flood risk area for operational reasons.

  2. Highly vulnerable: Police, ambulance, and fire stations; emergency dispersal points; basement dwellings; caravans and mobile homes for permanent residential use; and installations requiring hazardous substances consent.

  3. More vulnerable: Hospitals, residential dwellings, student accommodation, drinking establishments, nightclubs, hotels, and non-residential uses for health services, nurseries, and education.

  4. Less vulnerable: Shops, offices, general industry, storage and distribution, car parks, restaurants, and leisure uses.

  5. Water compatible: Flood control infrastructure, water treatment, navigation facilities, docks, ship building, lifeguard and coastguard stations, and amenity open space.

The compatibility matrix in the PPG combines vulnerability classification with flood zone to determine whether development is:

  • Appropriate: Development can proceed, subject to a site-specific Flood Risk Assessment
  • Subject to the Exception Test: The Exception Test must be passed
  • Not permitted: Development of that vulnerability should not be allowed in that flood zone

Correctly identifying the vulnerability classification is a critical first step in any FRA. An incorrect classification can lead to unnecessary test requirements or, worse, a flawed assessment that is rejected by the planning authority or Environment Agency. Aegaea’s flood risk assessments always clearly state the applicable classification and its policy implications, as detailed in our flood zones guide.

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