Short answer
Before you bid, exchange or instruct an architect, you need to know whether flood risk kills the site, triggers a full FRA, or just needs a planning note. Our desktop flood risk assessment answers that question in 48 hours from £199, so you can walk away from a Zone 3b residential plot before legal fees, topo survey and ecology windows start eating the budget.
The report screens an England development site against Environment Agency Flood Zones, surface water mapping, reservoir extents and historic flood records, then flags whether the site triggers the sequential test under NPPF paragraph 174. It is a triage and evidence layer, not a substitute for hydraulic modelling by a chartered flood engineer where Zone 3 mechanisms apply. Devolved nations (Scotland, Wales, Northern Ireland) use SEPA, NRW and DfI Rivers datasets respectively and are quoted on request.
Order a Site Appraisal or see a sample desktop FRA report.
When a flood risk assessment is triggered (England)
A planning application in England requires a flood risk assessment in defined circumstances under GOV.UK flood risk assessment guidance for planning. The triggers are:
- Any development located in Flood Zone 2 or Flood Zone 3 (including 3a and 3b functional floodplain).
- Sites over 1 hectare in Flood Zone 1, regardless of use.
- Sites with surface water flood risk per Environment Agency surface water mapping.
- Sites within or downstream of a critical drainage area as defined by the Local Plan or Strategic Flood Risk Assessment.
- Where the development changes the use class to a more vulnerable category (for example office to residential, or any "more vulnerable" or "highly vulnerable" classification).
- Where the LPA's Local List validation requirements explicitly require an FRA.
NPPF paragraph 174 sets the sequential test. Where the test is passed but the site sits in Zone 3, the exception test applies. Local validation lists and the LPA's SFRA can pull in additional sites that national data alone would miss, which is why a desktop screen always cross-references the relevant SFRA.
Flood Zone bands in brief: Zone 1 (low, less than 0.1% annual probability), Zone 2 (medium), Zone 3a (high), Zone 3b (functional floodplain). Worked examples we see weekly: a 6-unit infill in Zone 2, a barn conversion straddling a Zone 3a edge, and an edge-of-village brownfield plot under a critical drainage area.
What our desktop FRA covers (inputs and outputs)
The desktop layer pulls together the authoritative national datasets a competent reviewer would expect to see in the flood risk evidence section of a planning submission, and turns them into buyer-facing outputs you can act on.
| In our desktop FRA layer | Sourced from |
|---|---|
| Site flood zone classification (1 / 2 / 3a / 3b) | Environment Agency Flood Map for Planning |
| Surface water flood risk read | EA Risk of Flooding from Surface Water |
| Reservoir flooding extent | EA Risk of Flooding from Reservoirs |
| Historic flood event records | EA recorded flood outlines |
| Critical drainage area overlay | LPA Local Plan / SFRA where published |
| Sequential test applicability flag | NPPF paragraph 174 interpretation |
| Exception test applicability flag | NPPF paragraph 174 and SFRA reference |
| Climate change uplift overlay | EA peak rainfall and sea level guidance |
What you receive:
- Red-line boundary map pack with flood-zone overlays.
- Plain-English flood-zone conclusion and trigger verdict.
- Sequential and exception test applicability note.
- Recommended next-step commissions (specialist FRA, topo, drainage), with indicative cost and timeline ranges.
- Validation-risk flag against the relevant LPA Local List.
For complex Zone 3 sites where river, tidal and surface water mechanisms combine, full hydraulic modelling by a chartered flood engineer is the specialist commission triggered by our report. The desktop layer determines whether you need it at all, and where it sits in the critical path.
For the wider report stack and how flood interacts with heritage, transport and BNG, see what is included in our 48-hour desktop pack.
What this desktop FRA does not replace
Honest scope matters. The desktop is triage and evidence, not engineered design.
| Decision use | Desktop FRA verdict |
|---|---|
| Enough for | Pre-bid go/no-go, pre-exchange screening, pre-architect feasibility, Local List screening on Zone 1 sites under 1ha |
| May support | Pre-application advice meetings, scoping the FRA brief for a specialist, allocations and option-agreement decisions |
| Not enough for | Validation-stage FRA on Zone 2 or 3 residential schemes, hydraulic modelling, finished floor level design, SuDS sign-off, contested sequential test analysis |
Specialist commissions the desktop will name where triggered: hydraulic modelling (chartered flood engineer), topographical survey for finished floor levels, SuDS drainage strategy, Lead Local Flood Authority discharge agreement, and MRTPI input on contested "reasonably available sites" analysis. Reference: GOV.UK flood risk assessment guidance for planning.
Four packs sized to four decisions
| Pack | What it does for flood | Buyer moment | Price |
|---|---|---|---|
| Site Appraisal | Flood zone, surface water risk, sequential test trigger | Pre-bid, pre-offer (1-3 unit infill, auction deadline) | From £199, 48 hours |
| Feasibility Intelligence | Adds drainage outline and residual land value impact | Before exchange or option commitment (4-10 units) | From £895, 48 hours |
| Pre-Application Pack | Adds full desktop FRA evidence section for pre-app | Before architect spend, pre-app booked (6-20 units) | From £1,995, 48 hours |
| Planning Intelligence Pack | Desktop FRA evidence section to brief specialist hydraulic modelling | Application submission | Tailored, 48 hours |
For wider context, see our guide on what reports you need for planning permission and the development land due diligence guide.
Send the boundary today
How to order:
- Send postcode, red-line boundary (PDF, KML or DWG), intended use and indicative dwelling count via the order form.
- Pay on confirmation. We acknowledge within one working hour and confirm scope.
- Receive your PDF report in 48 hours: constraint screen, flood-zone trigger, sequential-test applicability and recommended specialist commissions.
£199 to walk away from a Flood Zone 3b residential site before solicitors are instructed. £895 for full feasibility before exchange. £1,995 to walk into pre-app with the FRA evidence section ready. For general context, see GOV.UK planning permission guidance.