Flood refusals and a failed sequential test

A sequential test failure appeal is the hardest flood case to win, because the test is not about engineering. It asks whether the development could reasonably go somewhere at lower flood risk, and a flood risk assessment showing the house will be safe does not answer it. Inspectors dismiss these appeals regularly, usually for one of two reasons: the appellant never carried out the test, or the area of search was drawn so tightly that no alternative site could possibly have been found.

A new dwelling is not minor development for flood risk purposes, whatever its size. That surprises self-builders more than any other point in this area.

What a sequential test refusal alleges

The refusal reason will say the proposal is contrary to policy because the sequential test has not been passed or has not been carried out. Read what that actually asserts.

It is not an allegation that the site will flood, or that the proposed floor levels are wrong, or that the drainage is inadequate. Those are separate matters and may appear as additional reasons. The sequential test allegation is that development of this type could reasonably be located in an area of lower flood risk, so the national policy aim of steering development to the lowest risk areas has not been met.

Three situations are usually behind it. No sequential test was submitted at all, because the applicant thought the flood risk assessment covered it. A test was submitted that considered only land in the applicant's ownership. Or a test was submitted with an area of search confined to a single village when the development could serve a wider area.

Taking the refusal apart into its separate allegations is the first step, and the approach is set out in the guide to reading a refusal notice and turning it into a plan.

Defining the area of search

This is where the case is usually won or lost, and it should be agreed with the authority in writing before the test is written.

The default area is the local planning authority's area. A smaller area can be justified where the nature of the development ties it to a particular place: a replacement dwelling on an existing footprint, a dwelling meeting an identified local need in a specific parish, a farm worker's dwelling tied to the holding, or a business expansion that has to adjoin existing premises.

A larger area can also be appropriate for development serving a wider catchment, which rarely helps an applicant.

The honest difficulty for a self-builder with a single plot is that an open-market dwelling has no functional tie to the location. The argument that the applicant owns this land and no other is not a flood risk argument, and inspectors say so.

What can work is a tie that is real: an agricultural or forestry functional need, a genuine local connection policy in the development plan, a site that is previously developed land within a settlement boundary where the plan positively supports infill, or a plot already allocated in the development plan for housing, in which case the test may have been applied at plan-making stage.

Evidence that reasonably available sites were considered

A Sequential Test that will survive an appeal is a search, documented. Assertion fails.

The method:

1. State the agreed area of search and the date it was agreed.
2. Identify the sources searched: the authority's housing land availability assessment, the brownfield land register, site allocations in the development plan, sites with extant permission, and commercially marketed sites.
3. List every site identified with its reference, area, flood zone and status.
4. Give a reason for discounting each one, by reference to availability, suitability or achievability rather than to the applicant's preference.
5. Record the search date, because availability changes and a test run two years ago will be challenged.
6. Conclude on whether any reasonably available site exists at lower flood risk.

The discounting reasons that carry weight are concrete: the site has planning permission for another use and is under construction, it is in a different ownership and not being marketed, it is too small for the development proposed, or it has a constraint that makes it undeliverable. The reasons that fail are that the site is more expensive, that the applicant does not own it, or that it is less convenient.

One point worth making plainly: carrying out a proper search sometimes shows that the test cannot be passed. Finding that out before the application costs a few days. Finding it out at appeal costs the fee and six months.

Where the test cannot be passed

If a reasonably available site at lower risk exists for the development proposed, the sequential test is failed and the exception test does not rescue it. The exception test is reached only where the sequential test has been passed.

At that point there are three honest options. Change the development so that it is no longer the same proposal in sequential terms, for example by proposing a less vulnerable use. Pursue the alternative site. Or accept that this site is not developable for housing and consider a water-compatible use instead.

Functional floodplain is a harder stop again. In Flood Zone 3b only water-compatible development and essential infrastructure are appropriate, and a dwelling is neither. No amount of mitigation changes that.

Running the exception test instead

Where the sequential test is passed but the site remains at risk, the Exception Test applies. It has two limbs and both must be satisfied, and the Framework's wording on the first has been revised, so take it from the current edition rather than from an older report.

The first limb concerns the wider benefits of the development to the community, weighed against the flood risk. For a single dwelling this is the weaker limb, because one house rarely delivers community benefits of any weight. Affordable housing, bringing derelict land back into use, or enabling a community facility can carry more.

The second limb is the engineering case: the development will be safe for its lifetime, taking account of climate change, will not increase flood risk elsewhere, and where possible will reduce flood risk overall. This is where a well-prepared Flood Risk Assessment does real work.

Residual risk and safe access

Safe access and egress is the issue that defeats otherwise competent submissions, and it is assessed for the design flood event including the climate change allowance.

The expectations in practice: dry access to a place of safety is preferred, with depth and velocity on any wet route assessed against published hazard criteria rather than asserted to be safe. Finished floor levels set above the design flood level with a freeboard, commonly 300 mm, with the design level stated and sourced. Flood resistance and resilience measures specified rather than described. Sleeping accommodation above the design flood level where that is achievable.

A flood warning and evacuation plan is a useful addition and not a substitute for safe access. The Environment Agency says so consistently, and an appeal that relies on an evacuation plan to cure an unsafe access route tends to fail on that point.

Climate change allowances are revised, so take them from the current Environment Agency guidance and state the version used.

Presenting the case on appeal

Structure the statement of case around the refusal reason, in this order: the area of search and why it is right, the search carried out with the site list as an appendix, the conclusion on reasonable availability, then the exception test if reached, then safe access and residual risk.

Lead with the area of search. If the inspector accepts it, everything else follows. If the inspector rejects it as too narrow, the rest of the statement is irrelevant.

Deal with the Environment Agency's position directly. Where it has objected, say what has changed since. Where it has not objected, say so, and distinguish its position on the engineering from the authority's position on the sequential test, because the two bodies are answering different questions.

A single-dwelling appeal on a sequential test point is one of the few planning appeals where the honest advice is often not to appeal, and instead to find a site in Flood Zone 1. Where the tie to the location is real and documented, the appeal is worth running. Where it is simply that this is the plot the applicant owns, it usually is not.

You can see which flood documents a constrained site needs, and start a draft, from the full report index.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.