Sequential and exception test report
A report supporting the flood risk sequential and exception tests required by planning policy.
About this service
National planning policy aims to steer new development towards areas with the lowest risk of flooding. Two tests put that aim into practice. The sequential test asks whether there are reasonably available sites with a lower flood risk where the development could go instead. The exception test applies in certain situations with greater flood risk and asks whether the development brings wider benefits and can be made safe for its lifetime. Councils will not normally approve schemes in Flood Zone 2 or 3 that fail them.
The council applies the tests, but the developer usually provides the evidence. We prepare reports that make that evidence clear and proportionate. For the sequential test, this means agreeing a sensible search area with the council and reviewing alternative sites against the scheme's requirements. For the exception test, it means drawing on the flood risk assessment to show safety and setting out the sustainability benefits of the proposal.
These reports work hand in hand with a site-specific flood risk assessment, either our major development assessment or, for smaller schemes, a minor development flood risk assessment. Preparing them together saves time and keeps the arguments consistent. We work on residential and mixed-use schemes up to five storeys, often on brownfield sites where regeneration benefits are part of the case.
When you need it
- The council requires the sequential or exception test for your site
- You're developing in flood zone 2 or 3
What's included
- Review of alternative sites where relevant
- Evidence for the exception test
- Supporting report for planning
How it works
- Confirm which tests applyWe check the flood zones, the vulnerability of the proposed use and local policy to confirm whether the sequential test, the exception test or both are needed, and whether any exemptions apply.
- Agree the search areaWe propose a search area suited to the type of development and its purpose, and where possible agree it with the planning officer before the site search starts.
- Review alternative sitesWe review sites from the local plan, housing land supply data and the market, testing whether each is reasonably available and suitable, and at lower flood risk.
- Build the exception test caseWhere required, we set out the wider sustainability benefits and use the flood risk assessment to show the scheme will be safe and will not increase risk elsewhere.
- Issue the reportWe issue a clear supporting report for the planning application, and help respond to any questions from the council or the Environment Agency while the application is being determined.
What you receive
Getting the search area right
Most sequential test arguments turn on the search area. A borough-wide search may be appropriate for general housing, but a narrower area can be justified where the development serves a specific local need or is part of a regeneration area. Getting the council to agree the area in pre-application discussions avoids the most common reason these reports are rejected. Your planning officer will confirm the council's approach.
Planning policy generally does not apply the sequential test to minor development or most changes of use, though councils still expect a flood risk assessment. Policy has also moved towards considering all sources of flooding, not only rivers and the sea, so a site in Flood Zone 1 with a known surface water problem may still face questions. Our drainage strategy guide covers how surface water fits in.
Frequently asked questions
What is the flood risk sequential test?
It is a planning test that steers new development to areas with the lowest risk of flooding. The developer must show there are no reasonably available sites, within an agreed search area, where the development could be built at a lower flood risk. The council decides whether the test is passed. If it is not, the application is usually refused regardless of how well the buildings are designed.
What is the exception test?
The exception test applies in some cases after the sequential test is passed, depending on the flood zone and how vulnerable the proposed use is. It has two parts: the development must provide wider sustainability benefits that outweigh the flood risk, and a site-specific flood risk assessment must show it will be safe for its lifetime without increasing flood risk elsewhere. Both parts must be met.
Does a house extension need a sequential test?
Generally no. Planning policy usually exempts minor development, such as householder extensions, from the sequential test, although a proportionate flood risk assessment is still needed in Flood Zones 2 and 3. Most changes of use are also exempt. New homes, including a new house in a garden, normally do need it. The council will confirm whether the test applies to your scheme.
How do I pass the sequential test in London?
Agree a sensible search area with the council early, then show with evidence that no reasonably available alternative sites at lower flood risk could accommodate the development. Sites already allocated in the local plan for similar uses are a common focus. A clear, well-documented report helps. Our sequential and exception test reports start from £500 + VAT, with the fixed fee confirmed in writing.