Sequential Test and Exception Test: A Developer's Guide

What Are the Sequential Test and Exception Test?

The Sequential Test and Exception Test are the two key planning policy mechanisms that control whether development can proceed in areas of flood risk. They are set out in the National Planning Policy Framework (NPPF) and elaborated in the Planning Practice Guidance (PPG) on flood risk.

The fundamental principle is straightforward: development should be directed to areas with the lowest flood risk. The Sequential Test enforces this principle by requiring applicants and planning authorities to demonstrate that development cannot reasonably be located in a lower-risk area. Where development in a higher-risk area is unavoidable, the Exception Test provides a second gateway, requiring the proposal to demonstrate wider sustainability benefits and that it will be safe from flooding.

These tests apply at two levels: at the strategic level during Local Plan preparation (where the LPA allocates sites for development) and at the application level when individual planning applications are submitted. For developers, the application-level tests are where the real challenge lies.

When Does Each Test Apply?

The requirement for the Sequential Test and Exception Test depends on the flood zone and the vulnerability classification of the proposed development.

Sequential Test

The Sequential Test applies to all proposals for new development in Flood Zones 2 and 3. There are limited exceptions:

• Sites allocated in the Local Plan where the Sequential Test was applied at the plan-making stage and the site is being developed in accordance with the allocation.
• Minor development and change of use — the PPG indicates that the Sequential Test does not apply to minor development (householder applications, small non-residential extensions) or change of use applications, though this exemption is not absolute and some LPAs apply the test more broadly.
• Development on previously developed (brownfield) land does not automatically exempt the site from the Sequential Test, though the brownfield status can be a factor in defining the search area.

Exception Test

The Exception Test is required in addition to the Sequential Test in specific circumstances:

Vulnerability Classification	Flood Zone 2	Flood Zone 3a	Flood Zone 3b
Water-compatible	No tests needed	No tests needed	No tests needed
Less vulnerable	Sequential Test only	Sequential Test only	Not permitted
More vulnerable	Sequential Test only	Sequential + Exception Test	Not permitted
Highly vulnerable	Sequential + Exception Test	Not permitted	Not permitted
Essential infrastructure	Sequential Test only	Sequential + Exception Test	Sequential + Exception Test

The Exception Test has two parts, and both must be passed:

• Part A: The development must provide wider sustainability benefits to the community that outweigh flood risk.
• Part B: The development must be safe for its lifetime, taking account of the vulnerability of its users, without increasing flood risk elsewhere, and where possible reducing flood risk overall.

The Sequential Test: Step by Step

Step 1: Define the Search Area

The search area is the geographic area within which alternative sites must be considered. By default, this is the local authority area, but it can be wider or narrower depending on the circumstances.

Arguments for a narrower search area include:

• Regeneration objectives — if the development is specifically intended to regenerate a defined area, the search area can be limited to that area.
• Functional requirements — if the development has a locational need (such as an extension to an existing facility, or a site with specific transport or infrastructure requirements).
• Local Plan policy — if the Local Plan directs development to a specific area or settlement.
• Brownfield land policy — if national or local policy prioritises brownfield development and the site is brownfield.

The search area should be agreed with the LPA before the assessment is prepared. Submitting a Sequential Test with an unagreed search area is a common source of delay.

Step 2: Identify Alternative Sites

Within the agreed search area, the applicant must identify all reasonably available sites that could accommodate the proposed development. Sources include:

• The LPA’s Strategic Housing Land Availability Assessment (SHLAA) or Brownfield Land Register
• Sites allocated in the Local Plan
• Sites with planning permission or prior approval
• Other known available sites (commercial property databases, land registry records)

The test is not theoretical — the sites must be “reasonably available.” This means they must be suitable for the type of development proposed, available for development (not under construction or committed to another use), and achievable within a reasonable timeframe.

Step 3: Compare Flood Risk

Each alternative site must be assessed for its flood risk. The comparison is straightforward: if there are reasonably available alternative sites in a lower flood zone, the Sequential Test is not passed and development should be directed to the lower-risk site.

The comparison considers the flood zone of the developable area of each site, not just the site boundary. A large site that is partly in Flood Zone 3 but has ample developable area in Flood Zone 1 may still be a viable alternative.

Step 4: Prepare the Sequential Test Report

The Sequential Test is formally documented in a report that sets out:

• The proposed development and its flood zone
• The agreed search area and justification
• The methodology for identifying alternative sites
• An assessment of each alternative site (location, flood zone, availability, suitability, achievability)
• A conclusion on whether any reasonably available alternative sites exist in lower-risk areas

The report should be clear, evidence-based, and honest. Cherry-picking sites to arrive at a predetermined conclusion is transparent to experienced planning officers and undermines credibility.

Step 5: LPA Decision

The Sequential Test is applied by the LPA, not the applicant. The applicant provides the evidence; the LPA makes the judgment. In practice, however, the quality of the applicant’s evidence is usually decisive. A thorough, well-evidenced Sequential Test report will carry significant weight.

The Exception Test: Step by Step

If the Sequential Test is passed (i.e., there are no reasonably available alternatives in lower-risk areas) but the flood zone and vulnerability classification require it, the Exception Test must also be satisfied.

Part A: Wider Sustainability Benefits

The development must provide wider sustainability benefits to the community that outweigh the flood risk. This is a qualitative judgment. Arguments typically include:

• Housing delivery — meeting an identified housing need, delivering affordable housing, or providing specialist housing (such as extra-care or supported living).
• Regeneration — bringing brownfield land back into productive use, remediating contaminated land, or revitalising a town centre.
• Economic benefits — creating jobs, providing commercial or retail space, or supporting local economic strategy.
• Community infrastructure — delivering schools, health facilities, community centres, or public open space.
• Environmental improvements — delivering biodiversity net gain, improving river corridors, or creating new public green space.

The benefits must outweigh the flood risk — not just be present. A generic claim of “providing housing” is unlikely to be sufficient. The argument must be specific, evidenced, and proportionate to the level of risk.

Part B: Safe for Its Lifetime

The development must be safe for its lifetime without increasing flood risk elsewhere, and where possible should reduce flood risk overall. This part of the Exception Test is demonstrated through a detailed flood risk assessment.

Specifically, Part B requires:

• Finished floor levels set above the design flood level (typically the 1% annual probability event plus climate change allowance plus freeboard).
• Safe access and egress — residents must be able to safely access and leave the site during a flood event. This does not necessarily mean dry access in all events, but the route must be safe (typically less than 600mm depth at a velocity that does not create a hazard).
• No increase in flood risk elsewhere — the development must not displace floodwater or increase runoff to the detriment of other properties. Floodplain compensation may be required.
• Flood resilience measures — where flooding above floor level is possible (such as in residual risk scenarios), the design should incorporate flood-resilient construction.
• Flood warning and emergency planning — for residential development in Flood Zone 3, a flood emergency plan is typically required, including procedures for receiving and acting on flood warnings.

Common Pitfalls

1. Not Agreeing the Search Area in Advance

Submitting a Sequential Test without pre-agreeing the search area with the LPA is the single most common mistake. It often leads to the LPA requesting a revised assessment with a different search area, wasting weeks of time.

2. Dismissing Alternative Sites Without Evidence

Each alternative site must be assessed against objective criteria. Dismissing sites as “unsuitable” without evidence — or applying unreasonable suitability criteria designed to exclude viable alternatives — undermines the credibility of the assessment.

3. Confusing the Sequential Test with Site Selection

The Sequential Test is not a market exercise. It does not ask whether the applicant prefers the proposed site, or whether the proposed site is the best site. It asks whether there are reasonably available alternative sites in lower-risk areas. The applicant’s commercial preferences are not relevant.

4. Weak Sustainability Arguments in the Exception Test

Generic claims of sustainability benefits without specific evidence are ineffective. The benefits must be tangible, evidenced, and proportionate to the flood risk.

5. Incomplete Part B Evidence

Part B of the Exception Test requires a robust FRA. Submitting an FRA that does not address safe access, does not apply current climate change allowances, or does not demonstrate no increase in risk elsewhere will result in the Exception Test being failed.

6. Assuming Local Plan Allocation Exempts from the Application-Level Test

While a Local Plan allocation can carry significant weight, it does not automatically exempt a planning application from the Sequential Test. If conditions have changed since the Plan was adopted (for example, new flood modelling data), the LPA may require the test to be re-applied.

Recent Policy Developments

The NPPF has been revised several times in recent years, and each revision has brought changes to flood risk policy. Key recent developments include:

• Strengthened Sequential Test requirements — the PPG now provides more detailed guidance on how to apply the Sequential Test, including the use of Strategic Flood Risk Assessments (SFRAs) as evidence.
• Climate change integration — the Exception Test now more explicitly requires consideration of climate change over the lifetime of the development.
• Surface water flooding — increasing recognition in planning policy that surface water flooding must be addressed alongside fluvial and tidal risk. Sites in Flood Zone 1 with significant surface water risk may now be subject to Sequential Test-type considerations under local policy.
• LLFA role — the role of the LLFA as statutory consultee has been strengthened, and their views on the Sequential Test and surface water management carry increasing weight.

Practical Tips for Passing the Tests

1. Engage with the LPA early. A pre-application discussion can clarify the search area, the LPA’s expectations for the Sequential Test evidence, and whether a formal Exception Test is required.
2. Commission the Sequential Test alongside the FRA. These documents should be prepared together, by the same team, to ensure consistency.
3. Be thorough but honest. The Sequential Test is a factual exercise. Present the evidence objectively and let it speak for itself.
4. Build the sustainability case from the outset. If you know the Exception Test will be required, develop the sustainability arguments as part of the planning strategy, not as an afterthought.
5. Design the scheme to pass Part B. Work with your flood risk consultant and architect to ensure the development is demonstrably safe — this means setting floor levels, designing access routes, and managing floodplain impact from the early design stages.

For specialist support with the Sequential Test and Exception Test, our team of flood risk consultants and planning advisors can help you navigate the process. Get in touch to discuss your site, or learn more about our flood risk assessment service.