Flood Risk Assessment Guidance for New Development
Flood risk assessment guidance for new development is important, as it is a key requirement for planning permission in the UK.
A flood risk assessment (FRA) is required for any new development or change of use in flood zones 2 and 3 and even sometimes in flood zone 1 under certain conditions.
Get in touch today for a free quote and the fastest FRA 48 hr turnaround in the UK.
A site-specific flood risk assessment by RIDA Reports:
- Identifies the flood zone.
- Assess all flood sources (rivers, sea, groundwater, reservoirs, and surface water).
- Accounts for climate change
Performs flood modelling as required - Illustrate how the development will avoid and mitigate flood risk.
- Follows UK planning rules.
- Coordinates with the design team.
- Speeds up the application and approval process
If you’re unsure whether your development needs an FRA, you can contact our flood risk consultants to clear up any doubts and get expert answers and guidance.
Our Clients
Flood Risk Assessment for Permitted Development
Permitted development rights in the UK allow certain small developments without full planning permission.
But these are very specific cases, and flood risk rules still apply. For example, if your permitted development is in flood zone 2 or 3, you must have to submit a site-specific flood risk assessment.
Even in flood zone 1, your permitted development project may need an FRA if it is above the threshold or if any flood problems are identified at your site.
Many developments in flood zone 1 that are up to 50m² (typical PD limit) generally do not need a full FRA, but if the development is in a critical drainage area or the proposal is larger than 50m², a FRA might still be required
You should never assume an FRA exemption just because your project is small or in flood zone 1; always refer to the UK planning guidelines on permitted development.
RIDA Reports provide Project Brief & Planning Context as the first step of flood risk assessment and expert consultation.
Flood Risk Assessment for a Major Development
Major developments are basically larger projects with higher planning obligations. The UK’s National Planning Policy Framework (NPPF) defines major developments based on two categories:
- Residential: A project of 10 homes or a site of 0.5 hectare or more is considered a major development
- Non-residential: development with a floorspace of 1,000m² or more, or a site of 1 hectare or more.
Flood risk assessment for major developments by RIDA Reports follows the national comprehensive guides and includes:
- A basic sequential test shows there are no alternative sites for this development
- An exception test if needed to demonstrate the development provides wider sustainability benefits that outweigh the flood risks. A drianage strategy will be required.
- Assess all flood sources and account for climate change
- Performs 1D and 2D river flood modelling for different scenarios
- Includes flood risk mitigation strategies
Recommends safe designs.
Our engineers combine expertise, national guidelines and a quick 48hr turnaround to generate a site-specific complaint flood risk assessment report for planning permission.
Flood Risk Assessment for a Minor Development
Minor developments are small projects, and they also need a flood risk assessment. According to gov.uk , for it to count as a “minor extension” under the Environment Agency guidance, it must be:
- a householder extension, or
- a non-domestic extension up to 250m² floorspace
And an FRA if required for minor extension if:
- It is in Flood Zone 2 or 3.
- It is a non-domestic extension up to 250m².
Our engineers perform flood risk assessment for minor developments , and our reports clearly quote relevant guidance from the Environment Agency’s standing advice.
Initial Flood Risk Appraisal from £750
We provide an initial flood risk appraisal report in 24 hours and clarify important points such as:
- Is it possible to develop this site
- Which parts of the site are most at risk of flooding
- What type of development is possible on this site
- Planning and design advice
- Whether a full flood risk assessment is needed after appraisal?
We offer 20% discount on flood risk assessment if required at a later date after the flood risk appraisal.
Strategic Development FRA from £1,900
Full FRA for strategic developments up to 50,000 square metres within flood zones 2 and 3.
Our reports for strategic development include:
- First draft in 48 hours
- Final report in 25 working days
- Sequential test
Exception test ( if required) - Assess access and escape routes in times of flood
- Flood compensation calculation
- Account for climate change
- Appropriate mitigation measures
- Recommends finishing flood levels
- Allows for set of revisions following the first issue of the report.
Major Development FRA from £1,250
We provide flood risk assessment for major Developments under 5,000 square metres within flood zones 2 and 3. This assessment is ideal for:
- Vulnerable residential developments in flood zones 2 and 3
- 4-9 dwellings less than 5,000 square metres or 0.5 ha
- Industrial and retail developments under 0.5ha
- Travelling community site development between 0 and 9 pitches
- Developments within flood zones 2 and 3 without hydraulic modelling
Our reports for major development include:
- First draft in 48 hours
Final report in 25 working days - Sequential test
Exception test ( if required) - Assess access and escape routes in times of flood
- Flood compensation calculation
- Account for climate change
- Appropriate mitigation measures
- Recommends finishing flood levels
- Allows for one set of revisions following the first issue of the report
Minor Development FRA from £750
Flood risk assessment for minor developments with sites under 2,50m² (e.g. small commercial units, minor housing schemes).
Our flood risk assessment report for minor developments includes:
- Initial draft in 48 hours
- Final report in 20 days
- Obtain predicted flood levels from the Enviroment Agency
- Report compliant with the Environment Agency and with the National Policy Planning Framework
- Assess access and escape routes in times of flood
- Calculated flood compensation
- Advice on flood warning and evacuation procedures
- Appropriate mitigation measures or flood resilient construction techniques
- Recommend finished floor levels
Frequently Asked Questions
We issue an initial flood risk assessment report in 48 hours. It includes flood zones, groundwater, flood sources and mitigation measures. Our final detailed report follows in 15-20 working days, and this is based on the time it takes to get flood data from the Enviroment Agency.
As above, our prices start at £750 and scale with project size. We always confirm costs upfront. For example, a basic householder extension FRA is £750, while a large strategic site might be £1,900.