What is a Flood Risk Assessment? 

As would be expected, Flood Risk Assessments serve to assess the flood risk associated with a development. Where relevant, they will also include mitigation measures to reduce to remove the flood risk. 

Where that risk is low, the Flood Risk Assessment is likely to be succinct and straightforward. Where the risk is high, the Flood Risk Assessment must be exceptionally thorough. 

What Flood Risk Assessments do Planning Direct offer?

Planning Direct offers entry-level Flood Risk Assessments only, covering the following circumstances:

  • Most developments in flood zone 1 (if a Flood Risk Assessment is required – see below); and
  • Development in flood zones 2 and 3 where there is no intensification in use OR a change of use is proposed to a use that is not more vulnerable to flooding.

If you require a higher-level Flood Risk Assessment, we can commission this for you. 

When is a Flood Risk Assessment required?

Flood Risk Assessments are required for all development in flood zones 2 and 3, no matter how minor. 

In flood zone 1, Flood Risk Assessments are required in the following circumstances:

  1. The site area is 1 ha or more;
  2. The site is subject to critical drainage problems, as identified by the Environment Agency;
  3. The site is identified in a strategic Flood Risk Assessment (i.e. a Flood Risk Assessment conducted by or on behalf of your local council as part of their local plan preparation) to be at increased flood risk in future; or
  4. The site may be subject to other sources of flooding and the development would introduce a more vulnerable use. 

How do I find out what flood zone my site is in?

The government provides a flood map that you can access for free online. Simply enter your postcode (or map reference) and you’ll be shown a map of the local area with all flood zones identified. There’s also an option to download a PDF report, with the map included, that identifies the flood zone of your site. Helpfully, this report will also tell you when a Flood Risk Assessment will be required for development at that site. 

What are the different flood zones and what do they mean?

The flood zones range from 1 to 3, although flood zone 3 is divided into two sub-categories 3a and 3b.

Flood zone 1: Low probability of flooding;

Flood zone 2: Medium probability of flooding;

Flood zone 3a: High probability of flooding; and

Flood zone 3b: The Functional Floodplain (land where water must flow or be stored during a flood event). 

What uses are vulnerable to flooding?

The Environment Agency has separated most uses and developments you could think of into different flood vulnerability classes. 

The classes are:

Essential infrastructure – this is development that must be located in flood risk areas, often because its purpose is to control and/or reduce flood risk;

Highly vulnerable – this is development that is the most vulnerable to flood risk, normally because it is has limited flood resilience, is subject to human occupation and opportunities to vacate in a flood event are limited;

More vulnerable – this is development that is still very vulnerable to flood risk, normally because it is subject to human occupation and/or would need to remain in use during a flood event;

Less vulnerable – this is development that is not considered to be at any notable flood risk;

Water-compatible development – this is development that is water-based or otherwise likely to withstand a flood event without issue. 

The below table identifies the flood vulnerability classification for some of the most common types of development:

Highly vulnerableBasement dwellings; caravans, mobile homes and park homes intended for permanent residential occupation
More vulnerableOther dwellings; hospitals; residential institutions (such as care homes and prisons); drinking establishments; health services; educational establishments; holiday let sites and short-let campsites and caravan sites; landfill sites
Less vulnerableCommercial sites (such as shops, offices, cafes, restaurants, industrial sites, leisure sites); agricultural sites; sewage treatment works
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