The Sequential Test And Exception Test Explained: How Flood Risk Decides Where You Can Build
The sequential test steers new development to the land with the lowest flood risk by asking whether a lower-risk site is reasonably available. The exception test is a second check for some uses, requiring wider benefits, lifetime safety and no extra flood risk elsewhere.
Policy references are to the National Planning Policy Framework published on 17 August 2026 (policies F5 and F6, Annex F). The Planning Practice Guidance on flood risk was last revised on 17 September 2025, before the new Framework, so its paragraph references to older NPPF numbering may be out of date. England only.
What Is The Sequential Test?
The sequential test is a planning policy test that asks whether a development could be built on land at lower flood risk instead. The NPPF states: "The aim of the sequential test is to steer new development to areas with the lowest risk of flooding from any source." If a suitable lower-risk site is reasonably available, the application should not go ahead on the riskier site.
The core rule, in policy F5: development proposals should not be located in areas at risk of flooding where alternative sites, appropriate for the development, are reasonably available in areas with a lower risk of flooding.
Three points shape how it is applied:
- All sources count. The test applies in areas at risk now or in future from any form of flooding, not only rivers and the sea.
- The search area is limited. The area to which the test is applied should not be greater than the anticipated catchment of the development in terms of its likely occupiers or users.
- Defences are ignored at first. The Planning Practice Guidance says the presence of flood risk management infrastructure should initially be ignored, because the long-term funding, maintenance and renewal of this infrastructure is uncertain.
How Does The Sequential Test Work Step By Step?
The sequential test works by agreeing a search area with the council, identifying other sites in that area, and showing that none of them is reasonably available at lower flood risk. The council decides whether the test is passed, using the land availability information it holds.
The steps:
- Check whether the test applies. It applies if any building, access route, land-raising or other vulnerable element is in an area at flood risk, unless an exemption below applies.
- Agree the area of search. The Environment Agency advises applicants to speak to the LPA early to discuss the sequential test and to determine an appropriate area of search for the test.
- Identify alternative sites in that area: sites allocated in the local plan, sites in land availability assessments, and sites such as those currently available on the open market.
- Compare flood risk. Look first for sites at low risk, then medium, then high, and consider variation within each zone.
- Show why each alternative is not reasonably available, or not at lower risk.
- The council decides whether the test is passed.
- If it is passed, check whether the exception test also applies.
What Counts As A "Reasonably Available" Alternative Site?
A site is reasonably available if it is suitable for the same development, meets the same need, and could realistically be developed at the same time. The Planning Practice Guidance states: "Sites should be considered 'reasonably available' for the purposes of the sequential test if their location is suitable for the type of development proposed, they are able to meet the same development needs and they have a reasonable prospect of being developed at the same time as the proposal."
What this means in practice:
| Question | Answer |
|---|---|
| Must the applicant own the alternative site? | No — such alternative sites do not need to be owned by the applicant to be considered 'reasonably available' |
| Can several smaller sites count as one alternative? | Yes, a series of two or more smaller sites can be considered |
| How far away can alternatives be? | No wider than the development's likely catchment of occupiers or users |
| Do open-market sites count? | Yes, including sites currently on the open market |
| Who decides? | The local planning authority |
The area of search sets how many alternative sites must be considered, which is why the Environment Agency advises agreeing it with the council early.
Which Developments Are Exempt From The Sequential Test?
Householder development, small non-residential extensions and most changes of use are exempt from the sequential test. The NPPF lists the exempt development types as householder development; small non-residential extensions with a footprint of less than 250m2; changes of use other than to a caravan, camping or chalet site, or to a mobile home or park home site.
The full list of exemptions in policy F5:
| Exemption | Detail |
|---|---|
| Householder development | The Environment Agency gives examples: a householder development like residential extensions, conservatories or loft conversions |
| Small non-residential extensions | Footprint of less than 250 m² |
| Changes of use | Except to a caravan, camping or chalet site, or to a mobile home or park home site |
| Allocated sites | Sites allocated in the development plan which were subject to the sequential test during plan preparation |
| No built development at risk | A site-specific FRA shows no building, access, escape route, land-raising or vulnerable element in an area at risk from any source, now or in future |
| Surface water risk only | Where the site would be at risk of surface water flooding only, the proposed layout, design, and mitigation measures would ensure that occupiers and users would remain safe from current and future surface water flood risk for the lifetime of the development, without increasing flood risk elsewhere |
An exemption from the sequential test does not remove the need for a flood risk assessment. Whether one is needed is set out in flood risk assessment.
What Is A Flood Risk Vulnerability Classification?
A flood risk vulnerability classification is the category a use falls into according to how badly flooding would affect it and its users. The NPPF's Annex F sets five classes, from essential infrastructure to water-compatible development, and they decide which uses are allowed in each Flood Zone.
| Class | Examples from Annex F, table 2 |
|---|---|
| Essential infrastructure | Essential transport and utility infrastructure that has to be in a flood risk area; wind turbines, solar farms, hydrogen production facilities, carbon capture, heat networks, data centres, electric vehicle charging stations |
| Highly vulnerable | Police, ambulance and fire stations and command centres; emergency dispersal points; basement dwellings; caravans, mobile homes and park homes for permanent residential use |
| More vulnerable | Hospitals; residential institutions such as care homes and prisons; Buildings used for dwelling houses (including floating/rising designs), student halls of residence, drinking establishments, nightclubs and hotels; health, nursery and educational uses |
| Less vulnerable | Buildings used for: shops; financial, professional and other services; restaurants, cafes and hot food takeaways; offices; general industry, storage and distribution; agriculture and forestry; car parks |
| Water-compatible | Flood control infrastructure; docks, marinas and wharves; water-based recreation; amenity open space and outdoor sports |
Where a development has parts in different classes, the highest vulnerability category should be used, unless the development is considered in its component parts.
Each class is then matched to each Flood Zone:
| Flood Zone | Essential infrastructure | Highly vulnerable | More vulnerable | Less vulnerable | Water-compatible |
|---|---|---|---|---|---|
| Flood Zone 1 | ✓ | ✓ | ✓ | ✓ | ✓ |
| Flood Zone 2 | ✓ | Exception test | ✓ | ✓ | ✓ |
| Flood Zone 3a | Exception test | Refuse | Exception test | ✓ | ✓ |
| Flood Zone 3b | Exception test | Refuse | Refuse | Refuse | ✓ |
✓ = exception test not required. "Refuse" = "Development should be refused" (Annex F, table 3). The sequential test still applies where required. What each zone means is in Flood Zones explained.
What Is The Exception Test?
The exception test is a second test, applied after the sequential test, for uses that Annex F allows in a Flood Zone only in exceptional circumstances. It asks whether the development's benefits justify its flood risk and whether it can be made safe.
The exception test is needed, under Annex F table 3, for:
- Highly vulnerable development in Flood Zone 2,
- More vulnerable development in Flood Zone 3a,
- Essential infrastructure in Flood Zones 3a and 3b.
It is not needed where the sequential test is not required: The exception test does not need to be applied to those forms of development, or in those circumstances, where the sequential test is not required. Before either test, the NPPF says Development proposals should be refused if the use is incompatible with the risk from river or sea flooding, as set out in Annex F, table 3.
What Are The Criteria Of The Exception Test?
The exception test has three criteria under the August 2026 NPPF, and a development must meet all of them. It must provide wider sustainability benefits that outweigh the flood risk, be safe for its lifetime, and not increase flood risk elsewhere.
The three criteria in policy F6:
- Wider sustainability benefits to the community that outweigh the flood risk.
- Safe for its anticipated lifetime, in accordance with policy F7.
- No increase in flood risk elsewhere and, where possible, a reduction in flood risk overall.
The test should be informed by a site-specific flood risk assessment.
Older guidance still refers to two parts. The previous NPPF had a two-part exception test, and the Environment Agency's standing advice, last updated on 28 May 2026, still says applicants must "you need to satisfy both elements of the exception test". The Framework published on 17 August 2026 sets three criteria, so check which version your council is applying.
What Happens If Your Application Fails The Sequential Test?
If your application fails the sequential test, the council should refuse it, because a lower-risk site was reasonably available. A strong flood risk assessment or flood-resilient design does not make up for a failed sequential test, and the exception test cannot be used to pass it.
Your options:
- Challenge the search area if it is wider than the development's likely catchment of occupiers or users.
- Show the alternatives are not reasonably available, for example because they cannot meet the same need or could not be developed at the same time.
- Redesign the layout so that no building, access or vulnerable element sits in an area at risk; policy F5 exempts such sites.
- Choose a different site.
- Appeal the refusal, with evidence on the points above.
What different building projects involve in each Flood Zone is set out in building in a flood zone.
Sources (Verified 17 Sep 2026)
| Claim | Source |
|---|---|
| F5 aim, reasonably available, catchment, exemptions, allocated and surface-water-only sites; F6 incompatible uses, three criteria, exception test not needed; Annex F tables 2 and 3 | National Planning Policy Framework (17 Aug 2026) |
| Reasonably available definition; not owned by applicant; series of smaller sites; defences ignored initially; revision date | Planning Practice Guidance: Flood risk and coastal change |
| Area of search; open market sites; householder examples; "both elements" wording | Environment Agency, Flood risk assessment: standing advice (28 May 2026) |
Frequently Asked Questions
Does A House Extension Need A Sequential Test?
No. Householder development, including residential extensions, conservatories and loft conversions, is exempt from the sequential test. It may still need a flood risk assessment if it is in Flood Zone 2, 3 or 3b or another trigger applies.
Is A Change Of Use Exempt From The Sequential Test?
Most changes of use are exempt. The exception is a change of use to a caravan, camping or chalet site, or to a mobile home or park home site, which still needs the sequential test.
How Many Parts Does The Exception Test Have?
Under the National Planning Policy Framework published on 17 August 2026, the exception test has three criteria. Some older guidance, including Environment Agency standing advice, still refers to two elements.
Who Decides If The Sequential Test Is Passed?
The local planning authority decides, using the land availability information it holds and the evidence the applicant provides on alternative sites within the agreed area of search.