Flood Risk Vulnerability Classification Checker (NPPF 2026 Annex F)
This checker gives the flood risk vulnerability classification of a proposed use, and what that class means in the site's flood zone, under the 2026 National Planning Policy Framework (NPPF). Choose the zone and the use: the checker returns the class from Annex F Table 2, quoted word for word, and the Table 3 answer ("yes", "Exception test required" or "no"). It then says whether the Sequential and Exception Tests apply or the scheme is exempt, and what the flood risk assessment (FRA) has to show. The tables now sit in Annex F of the NPPF. Most pages online still quote the old "Annex 3" and the Planning Practice Guidance tables.
Need the flood risk assessment? Send us the site plan and the proposed use through our fee proposal form. What a report covers is on our flood risk assessment page.
How to use the flood risk vulnerability classification checker
Find the flood zone of the land inside the red line on the Flood Map for Planning. The map shows Zones 1, 2 and 3 but does not separate Zone 3a from Zone 3b, the functional floodplain. Annex F Table 1 says local planning authorities "should identify in their strategic flood risk assessments areas of functional floodplain". If the SFRA is not to hand, choose "Zone 3, not sure" and the checker shows both answers.
Choose the use from the common uses at the top of the list, or from the Table 2 items below them. A use that Table 2 does not cover returns "Not listed: ask us", because the class then has to be argued by comparison.
Choose the type of application. Householder development, small non-residential extensions and most changes of use are exempt from the Sequential Test, and that changes the Exception Test answer.
Add a second use for a mixed scheme. The notes to Table 3 say: "Some developments may contain different elements of vulnerability, and the highest vulnerability category should be used, unless the development is considered in its component parts." The checker reports the stricter answer.
Figure 1. The order of the questions, from the proposed use to policy F7.
The five vulnerability classes: Annex F Table 2
Annex F of the NPPF (published on GOV.UK on 29 September 2026) puts every use in one of five classes. The items below are quoted from Table 2.
| Class | Uses listed in Annex F Table 2 | |---|---| | Essential infrastructure | Essential transport infrastructure (including mass evacuation routes) which has to cross the area at risk. Essential utility infrastructure which has to be located in a flood risk area for operational reasons, including for electricity generation and storage, electricity network infrastructure, telecommunications infrastructure, water supply reservoirs and water treatment works that need to remain operational in times of flood. Wind turbines. Solar farms. Hydrogen production facilities. Carbon Capture, distribution and storage facilities. Heat networks. Data Centres. Electric vehicle charging stations. | | Highly vulnerable | Police and ambulance stations, fire stations and command centres. Emergency dispersal points. Basement dwellings. Caravans, mobile homes and park homes intended for permanent residential use. Installations requiring hazardous substances consent or which fall under The Control of Major Accident Hazards Regulations 2015 (with a demonstrable need for a coastal or water-side location, these "should be classified as 'Essential Infrastructure'"). Installations requiring a radioactive substances regulations permit for disposal to landfill or dedicated near-surface disposal by burial. | | More vulnerable | Hospitals. Residential institutions such as residential care homes, children's homes, social services homes, prisons and hostels. Buildings used for dwelling houses (including floating/rising designs), student halls of residence, drinking establishments, nightclubs and hotels. Non–residential uses for health services, nurseries and educational establishments. Landfill and sites used for waste management facilities for hazardous waste. Sites used for holiday or short-let caravans and camping, subject to a specific warning and evacuation plan. | | Less vulnerable | Police, ambulance and fire stations which are not required to be operational during flooding. Buildings used for: shops; financial, professional and other services; restaurants, cafes and hot food takeaways; offices; general industry, storage and distribution; non-residential institutions not included in the 'more vulnerable' class; and assembly and leisure. Land and buildings used for agriculture and forestry. Waste treatment (except landfill and hazardous waste facilities). Minerals working and processing (except for sand and gravel working). Water treatment works which do not need to remain operational during times of flood. Sewage treatment works, if adequate measures to control pollution and manage sewage during flooding events are in place. Car parks. Land-raising (unless part of or enabling a development with a higher vulnerability classification). | | Water-compatible development | Flood control infrastructure. Water transmission infrastructure and pumping stations. Sewage transmission infrastructure and pumping stations. Sand and gravel working. Docks, marinas and wharves. Navigation facilities. Ministry of Defence installations. Ship building, repairing and dismantling, dockside fish processing and refrigeration and compatible activities requiring a waterside location. Water-based recreation (excluding sleeping accommodation). Lifeguard and coastguard stations. Amenity open space, nature conservation and biodiversity, outdoor sports and recreation and essential facilities such as changing rooms. Essential ancillary sleeping or residential accommodation for staff required by uses in this category, subject to a specific warning and evacuation plan. |
Which uses are allowed in which flood zone: Annex F Table 3
Table 3 sets each class against each flood zone. Its key reads "yes: Exception test is not required" and "no: Development should be refused".
Figure 2. Annex F Table 3 as a colour matrix. Highly vulnerable uses need the Exception Test in Zone 2; only water-compatible uses and essential infrastructure can go in Zone 3b.
Two notes go with it. In Zone 3a "essential infrastructure should be designed and constructed to remain operational and safe in times of flood" (†). In Zone 3b (††), essential infrastructure that has passed the Exception Test, and water-compatible uses, should be designed and constructed to "remain operational and safe for users in times of flood". They should also "result in no net loss of floodplain storage" and "not impede water flows and not increase flood risk elsewhere". Policy F6(1)(a) in Chapter 18 makes the "no" cells a reason for refusal. 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".
Zones 2 and 3 cover river and sea flooding only. A Flood Zone 1 site can still be at risk from surface water or groundwater, and a council can then ask for an FRA. Our guide to flood risk assessment if you're not in a flood zone covers it, and Flood Zones 1, 2 and 3 explained sets out the zones.
The Sequential Test and who is exempt
Policy F5(2) says the Sequential Test "should be used in areas known to be at risk now or in the future from any form of flooding". The exceptions are allocated sites tested at plan stage (F5(2)(a)), sites where the FRA shows no built development in an area at risk (F5(2)(b)), and three types of development under F5(2)(c):
"Householder development;"
"Small non-residential extensions (with a footprint of less than 250m2); and"
"Changes of use, other than changes of use to a caravan, camping or chalet site, or to a mobile home or park home site."
Figure 3. Which applications need each test under policies F5(2) and F6(2).
How the test is run, and how wide the search area should be, is on our page on the Sequential and Exception Tests and in our post on the Sequential Test under the NPPF 2026.
The Exception Test
Where Table 3 says "Exception test required", policy F6(1)(b) requires the development to meet all three criteria, in addition to the Sequential Test:
"Provide wider sustainability benefits to the community that outweigh the flood risk;"
"Be safe for its anticipated lifetime in accordance with policy F7; and"
"Not increase flood risk elsewhere and, where possible, reduce flood risk overall."
Policy F6(2) adds that the test does not need to be applied "To those forms of development, or in those circumstances, where the sequential test is not required, as set out in policy F5". Annex F does not list extensions. In practice councils and the Environment Agency class an extension with the building it extends, so an extension to a house is "more vulnerable". In Zone 3a Table 3 then lists the Exception Test, but as householder development neither test is applied. The FRA still has to show, under policy F7, that the extension is safe for its lifetime and does not increase flood risk elsewhere. Our guide to flood risk standing advice for extensions, with its floor level checker, covers those cases.
Worked example: the generator the Environment Agency classed as essential infrastructure (25/01976/FUL)
Application 25/01976/FUL, at Waterside Apartments, Pavilion Road, West Bridgford, Nottingham, was for a standby generator in the car park of a high-rise residential building. The generator is for the building's fire-fighting lifts and life-safety systems if the mains supply fails. The site lies in Flood Zone 3 on the River Trent floodplain, behind defences. AFC prepared the FRA.
Figure 4. The site and the generator position inside the design flood extent (AFC FRA Rev 2, page 11).
The classification. AFC's FRA stated that the emergency generator "does not constitute 'essential infrastructure'" and that the Sequential and Exception Tests were therefore not required. The Environment Agency's Lower Trent team objected in December 2025 (LT/2025/129619/01-L01). Its Planning Advisor replied by email that national policy classed electricity supply including generation as essential infrastructure, and that a flooded generator could compromise fire safety. Under Annex F today the unit falls in "Essential utility infrastructure which has to be located in a flood risk area for operational reasons, including for electricity generation and storage". The checker returns "Exception test required" for that class in Zone 3a or 3b, with note † or ††.
The level. EA Product 4 data (EIR/2025/36206) gave a design flood level of 23.83 mAOD at the model node closest to the generator, for the defended 1% AEP plus 30% climate change event. The flood depth on site is about 0.22 m. FRA Rev 2, issued on 14 January 2026, raised the generator to 24.13 mAOD, 300 mm above that level, as the Greater Nottingham SFRA (2017) asks for minor development.
Figure 5. The class the EA applied, and the level that cleared the objection: 24.13 mAOD, 300 mm above the 1% AEP + 30% CC level.
The outcome. The EA's letter of 18 February 2026 (LT/2025/129619/02-L01) reads: "We rescind our previous objection and are satisfied that the proposal now meets the requirements of being safe from flooding for the lifetime of the development". Rushcliffe Borough Council granted permission on 10 July 2026, and condition 4 states: "The generator shall be installed 24.13 metres above Ordnance Datum (AOD)".
Rev 2 kept the statement that the generator was not essential infrastructure. The council's report recorded the EA's withdrawal and the "limited size of the proposed development" and did not discuss either test. The lesson for an FRA is to classify plant by its function, and to design it to Table 3's note for that class from the first issue. The Waterside case study has the rest of the job, and our guide to an Environment Agency objection on flood risk covers how the objection was cleared.
Common classification mistakes
Plant, generators and substations treated as ancillary. Equipment that keeps a building safe in a flood (fire-fighting lift power, pumps, life-safety systems) can be classed by what it does, not by the building it serves. Waterside shows the cost of getting it wrong: an objection and a redesign.
Basements. "Basement dwellings" are highly vulnerable: "no" in Zone 3a and Exception Test in Zone 2. A bedroom in a new basement can move a whole scheme into that class. Our post on basement developments under the NPPF 2026 covers it.
A change of use that raises the class. A change of use is exempt from both tests, but Table 3 still applies. The Planning Practice Guidance says "Changes of use can increase the vulnerability of the development or result in occupation or use by people who are more vulnerable than the previous occupants/users to risks from flooding" (paragraph 052, Reference ID 7-052-20220825). Offices to flats moves from less to more vulnerable. Our flood risk assessment for change of use page covers what the FRA then needs. The PPG still refers to the old "Annex 3" numbering.
Mixed schemes reported by the main use only. A hotel with a basement flat for staff, or shops with flats above, takes the highest class unless the parts are considered separately.
Zone 3a and 3b taken from the wrong map. The Flood Map for Planning shows Zone 3 only. The SFRA identifies Zone 3b, and a more vulnerable use there is "no" rather than "Exception test required".
Figure 6. Three AFC jobs through the classification. The Leicester gym and the Stanmore children's home are written up as case studies.
What to submit
The vulnerability class of each part of the scheme, with the Annex F Table 2 line it comes from.
The flood zone from the Flood Map for Planning, and the SFRA's Zone 3a or 3b status where the site is in Zone 3.
The Table 3 answer, and the Sequential and Exception Test position or the exemption that applies (F5(2), F6(2)).
For a change of use, the existing and proposed classes.
The evidence that the development is safe for its lifetime (policy F7): floor and plant levels in mAOD against the design flood level, safe access and escape, flood resistance and resilience. The flood hazard rating calculator helps with the access route.
Frequently asked questions
What is the flood risk vulnerability classification?
The five classes the NPPF puts every use into, according to how vulnerable it is to flooding: essential infrastructure, highly vulnerable, more vulnerable, less vulnerable and water-compatible development. They are listed in Annex F Table 2 of the NPPF (2026). Table 3 then sets each class against Flood Zones 1, 2, 3a and 3b.
Is a house "more vulnerable" in flood risk terms?
Yes. Table 2 lists "Buildings used for dwelling houses (including floating/rising designs)" as more vulnerable. A basement dwelling is highly vulnerable.
Can you build houses in Flood Zone 3?
In Zone 3a, a new house needs the Sequential Test and then the Exception Test. In Zone 3b, the functional floodplain, Table 3 says "no" for more vulnerable uses, so a new house should be refused. Extensions to existing homes are householder development and exempt from both tests, but still need an FRA. In Zone 3b, check the council's local plan policy on extensions first. Our Sequential and Exception Test page explains the tests.
What counts as essential infrastructure for flood risk?
Essential transport and utility infrastructure that has to be in the flood risk area, including electricity generation and storage and network infrastructure (Annex F Table 2). Table 2 also lists wind turbines, solar farms, hydrogen production, carbon capture, heat networks, data centres and electric vehicle charging stations. In 2025 the Environment Agency treated a standby generator for fire-fighting lifts as essential infrastructure.
Is a basement flat "highly vulnerable"?
Yes. "Basement dwellings" are listed as highly vulnerable in Annex F Table 2. That makes a basement flat "no" in Flood Zones 3a and 3b, and subject to the Exception Test in Flood Zone 2.
Does a change of use need the Sequential Test?
Not usually. Policy F5(2)(c) exempts "Changes of use, other than changes of use to a caravan, camping or chalet site, or to a mobile home or park home site." The FRA still has to show the new use is safe, and Table 3 still applies. See our change of use FRA page.
When is the Exception Test required?
Where Annex F Table 3 says "Exception test required": highly vulnerable uses in Zone 2, essential infrastructure and more vulnerable uses in Zone 3a, and essential infrastructure in Zone 3b. It is not applied where the Sequential Test is not required (policy F6(2)(a)).
Where are the vulnerability tables in the new NPPF?
In Annex F, "Managing flood risk and coastal change", published on GOV.UK on 29 September 2026: Table 1 (flood zones), Table 2 (vulnerability classification) and Table 3 (compatibility). The policies that use them are F4 to F7 in Chapter 18.
Ask us about your site
AFC prepares flood risk assessments, Sequential Tests and Exception Tests for householder schemes, changes of use, new homes and infrastructure, from the Environment Agency's modelled data and the council's SFRA. Send the site address, the drawings and the proposed use through our fee proposal form, and we will set out the class, the tests and what the report needs.
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