Desktop Flood Risk Assessment for Planning (England 2026)

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 from £295, 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 policy F5. 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.

Request a Site Appraisal quote 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:

1. Any development located in Flood Zone 2 or Flood Zone 3 (including 3a and 3b functional floodplain).
2. Sites over 1 hectare in Flood Zone 1, regardless of use.
3. Sites with surface water flood risk per Environment Agency surface water mapping.
4. Sites within or downstream of a critical drainage area as defined by the Local Plan or Strategic Flood Risk Assessment.
5. 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).
6. Where the LPA's Local List validation requirements explicitly require an FRA.

NPPF policy F5 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.

Two things changed when the Framework was republished on 17 August 2026, and both matter commercially. First, policy F5(2) now lists exemptions: householder development, non-residential extensions with a footprint under 250m², most changes of use, sites already sequentially tested when they were allocated, and sites where a site-specific flood risk assessment shows no built development would sit in an at-risk area. A site at risk from surface water alone can also fall outside the test where layout, design and mitigation keep occupiers safe for the lifetime of the development. Second, policy F5(1) caps the search area: it should be no greater than the anticipated catchment of the development in terms of its likely occupiers or users. That is a limit on how wide an objector can push the "reasonably available sites" argument, and it did not exist before.

None of that removes the need to screen. An exemption has to be evidenced to be relied on, and the exemption for a surface-water-only site is conditional on the mitigation actually working, which is a design question rather than a mapping one. The desktop report tells you which limb of policy F5 your site sits under and what evidence the exemption would need.

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.

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 desktop pack.

Four packs sized to four decisions

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 request a quote:

1. Send the postcode, intended use and indicative dwelling count with a quote request. Send the red-line boundary by email when we reply.
2. We acknowledge within one working hour, then confirm the scope, the price and the delivery date before you pay.
3. Receive your PDF report: constraint screen, flood-zone trigger, sequential-test applicability and recommended specialist commissions.

£295 to walk away from a Flood Zone 3b residential site before solicitors are instructed. £995 for full feasibility before exchange. £2,250 to walk into pre-app with the FRA evidence section ready. For general context, see GOV.UK planning permission guidance.

Request a Site Appraisal quote or see a sample desktop FRA report.