Exception Test (Flood)

Part One requires demonstrating that the development provides wider sustainability benefits to the community that outweigh the flood risk. This is a planning judgement informed by the benefits the scheme offers, such as housing delivery, regeneration, employment, or environmental improvement. Part Two requires demonstrating that the development will be safe for its lifetime without increasing flood risk elsewhere, and where possible reducing flood risk overall. This is evidenced through the Flood Risk Assessment.

The NPPF does not define a fixed list of qualifying benefits. Relevant benefits might include delivery of housing to meet identified need (particularly affordable housing), regeneration of a derelict or contaminated site, creation of employment or economic activity, provision of community facilities such as schools or healthcare, environmental improvements including biodiversity net gain or public open space, and infrastructure improvements that benefit the wider area. The benefits must be specific and evidenced, not generic assertions.

Safety is demonstrated through the Flood Risk Assessment, which must show that the development can withstand the design flood event for its intended lifetime (100 years for residential). Key evidence includes finished floor levels set above the design flood level with an appropriate freeboard, safe access and egress routes that remain passable during a flood, flood-resilient and flood-resistant construction measures, an emergency flood plan, and warning and evacuation procedures. The FRA must account for climate change over the lifetime of the development.

No. The Exception Test only applies to specific combinations of development vulnerability classification and flood zone. For example, 'less vulnerable' uses (offices, shops) in Flood Zone 3a need the Sequential Test but not the Exception Test. 'More vulnerable' uses (housing) in Flood Zone 3a need both tests. Some combinations are not permitted at all — 'highly vulnerable' uses in Flood Zone 3a or 3b cannot be approved under any circumstances. The compatibility tables in Planning Practice Guidance set out exactly which combinations apply.

Yes, residential development in Flood Zone 3a can pass the Exception Test if both parts are satisfied. Residential development is classified as 'more vulnerable,' and in Flood Zone 3a it must pass both the Sequential Test and the Exception Test. In Flood Zone 3b (the functional floodplain), residential development is not permitted at all — the Exception Test cannot override this prohibition. The distinction between 3a and 3b is therefore critical.

The Sequential Test asks: is there somewhere else this development could go that is at lower flood risk? The Exception Test asks: given that it needs to be here, does it provide sufficient benefits to justify the flood risk and can it be made safe? The Sequential Test is a site selection exercise; the Exception Test is a justification and safety exercise. The Sequential Test must be passed first, and the Exception Test only applies where specific vulnerability/flood zone combinations require it.

A planning inspector considering an appeal will make their own assessment of whether the Exception Test is met, drawing on the evidence before them. If the inspector concludes that the wider sustainability benefits do outweigh the flood risk and the development can be made safe, they may allow the appeal even if the council concluded otherwise. However, inspectors take flood risk seriously and will scrutinise the evidence carefully. The Environment Agency's position on the application will carry significant weight.

The Environment Agency is a statutory consultee for planning applications in Flood Zones 2 and 3. They focus primarily on Part Two of the Exception Test — whether the development will be safe and will not increase flood risk elsewhere. They review the Flood Risk Assessment and advise the local authority on its adequacy. Part One — the wider sustainability benefits — is primarily a matter for the local planning authority to assess, as it involves planning judgement rather than technical flood risk expertise.

For residential development, the assumed lifetime is 100 years. For commercial development, a shorter period — typically 60 years — may be appropriate, depending on the nature of the use. The Flood Risk Assessment must demonstrate safety for the full assumed lifetime, including the effects of climate change on flood risk over that period. This means that a site which is currently safe from flooding may fail the test if climate change projections show that flood risk will increase significantly within the development's lifetime.

Section 106 obligations such as affordable housing contributions, open space provision, or highway improvements that the development would deliver can be cited as wider sustainability benefits. However, these must be benefits that go beyond the minimum policy requirements — if you are simply delivering the standard 35% affordable housing that any development in the borough would provide, this may not be considered an exceptional benefit that justifies development in a flood risk area. The benefits need to be weighed against the flood risk, and genuinely exceptional or site-specific benefits carry more weight.