Understanding Flood Risk Assessments

When planning a new development or redeveloping an existing site, understanding the potential for flooding is essential. As a developer or architect, you’re also responsible for considering how your project could impact flood risk in the surrounding area.

A Flood Risk Assessment (FRA) evaluates these risks and outlines practical measures to reduce or manage them. It is often a requirement for planning applications, especially in areas with a known flood risk, designated by the Environment Agency or your Local Planning Authority.

Whether your project is residential or commercial, an FRA provides a clear picture of the flood-related challenges and how they can be addressed. The level of detail in the assessment will depend on the nature, location, and scale of the proposed development.

A Flood Risk Assessment (FRA) is required under the National Planning Policy Framework (NPPF) and the Environment Agency (EA) guidance on development and flood risk when a development is located in i) Flood Zone 2 or 3, ii) a Critical Drainage Area, or iii) the site is greater than or equal to 1 hectare in size, for sites in Flood Zone 1.

Some Local Planning Authorities may have specific requirements that prompt Flood Risk Assessments in areas at any risk of flooding, including surface water and ground water.

You’ll also need to consult the Environment Agency if your development is within 20 meters of an Environment Agency designated main river. Flood permits will be required if the proposal includes temporary and permeant works within 8m of a EA river and 16m of a tidal EA river.

There may be additional circumstances that prompt the requirement of an FRA. If in doubt, get in touch with one of our Flood Risk Consultant.

What are the implications to my development?

The implications of a Flood Risk Assessment will depend on the scale and nature of a development.

If you are planning to extend your property or changing its use within Flood Zone 2 or Flood Zone 3b, then flood resilient and resistant measures are likely to be sufficient to address the requirements of your Local Planning Authority. These measures could include raising electric sockets and gas intakes above the design flood level, using flood resistant materials and opting for flood-proof doors.

However, if you are planning to develop a new property, flood resilient and resistant measures are unlikely to be sufficient. New properties (including single houses) will require a careful consideration of the site layout, by steering vulnerable uses towards low flood risk areas. Compliance with the Environment Agency’s standards is of essence, with properties affected by Flood Zone 2 and 3 requiring Finished Floor Levels to be raised above the design flood level.