What are the Sequential and Exception Tests?
Estimated reading time 4 minutes
If you’re a property developer, navigating planning requirements can feel like an uphill battle. The Sequential Test and Exception Test might seem like bureaucratic obstacles, but understanding how to approach them strategically can help unlock development opportunities in areas that might otherwise be off-limits. These tests are part of national planning policy, ensuring development is sustainable and does not increase flood risk.
What is the Sequential Test?
The Sequential Test is designed to steer development towards areas with the lowest risk of flooding. This doesn’t mean that sites in Flood Zones 2 or 3 are automatically unviable—it simply means that you need to demonstrate that there are no suitable lower-risk sites available before proceeding.
According to the National Planning Policy Framework (NPPF) December 2024 Update, paragraph 175 states:
"The sequential test should be used in areas known to be at risk now or in the future from any form of flooding, except in situations where a site-specific flood risk assessment demonstrates that no built development within the site boundary, including access or escape routes, land raising or other potentially vulnerable elements, would be located on an area that would be at risk of flooding from any source, now and in the future (having regard to potential changes in flood risk)."
When is a Sequential Test Required?
A Sequential Test is required for most developments in Flood Zones 2 and 3, unless an exemption applies. Exemptions include:
- Minor extensions or alterations to existing buildings.
- Changes of use that do not increase flood risk (e.g., converting a commercial unit into residential where no additional flood risk is introduced).
- Developments on land already allocated for a specific use in an adopted Local Plan.
- A site-specific Flood Risk Assessment (FRA) proving that all built development is positioned outside areas at risk of flooding from all sources, including surface water, groundwater, reservoirs, and future climate change impacts.
How to Navigate the Sequential Test
To meet the requirements of the Sequential Test, you need to:
- Define the search area for alternative sites—this should be proportionate and justifiable.
- Provide evidence that there are no suitable lower-risk sites available.
- Justify why the proposed site is necessary, particularly for developments contributing to local housing targets, regeneration, or infrastructure projects.
Engaging with local planning authorities early and preparing a well-evidenced case can significantly reduce delays.
What is the Exception Test?
If your site does not pass the Sequential Test, the Exception Test offers an alternative route to secure planning permission.
As outlined in paragraph 178 of the NPPF December 2024 Update:
"To pass the exception test it should be demonstrated that: (a) the development would provide wider sustainability benefits to the community that outweigh the flood risk; and (b) the development will be safe for its lifetime taking account of the vulnerability of its users, without increasing flood risk elsewhere, and, where possible, will reduce flood risk overall."
To pass the Exception Test, you must demonstrate:
- Wider Sustainability Benefits – Your development should provide clear community benefits, such as:
- Supporting local economic growth and job creation.
- Contributing to much-needed housing supply.
- Improving local infrastructure or facilities.
- Flood Risk Management – The development must be designed to be safe for its entire lifetime, with mitigation measures such as:
- Raising floor levels above expected flood levels.
- Incorporating Sustainable Drainage Systems (SuDS) to manage surface water effectively.
- Using flood-resistant materials, barriers, and emergency evacuation plans to improve resilience.
A robust Flood Risk Assessment (FRA) is essential to demonstrating that these measures are in place and will be effective.
Using the Sequential and Exception Tests to Your Advantage
While these tests may seem like hurdles, they can actually enhance your planning application by:
- Strengthening your case for approval by showing responsible flood risk management.
- Increasing the resilience of your development, reducing long-term flood-related costs and liabilities.
- Building trust with local authorities and communities by demonstrating sustainable development principles.
How Unda Can Help
At Unda, we specialise in supporting property developers through the planning process, helping to navigate the complexities of the Sequential and Exception Tests. Our services include:
- Comprehensive Flood Risk Assessments (FRAs) – Providing clear, detailed evidence to support planning applications.
- Sequential and Exception Test reports – Ensuring compliance with national and local planning policies.
- Sustainable Drainage Systems (SuDS) strategies – Managing surface water runoff effectively to reduce flood risk and enhance site sustainability.
By working with Unda, you can simplify the planning process, minimise delays, and maximise your site’s potential while ensuring responsible flood risk management.
One of our experienced Flood Risk Consultants will get back to you within 60 minutes