What are the legal requirements for flood risk assessments in construction projects?

Legal requirements for Flood Risk Assessments in UK construction are primarily mandated by the National Planning Policy Framework (NPPF).

The NPPF states that FRAs are statutorily required for new development proposals located within Flood Zones 2 & 3, and for all new development proposals larger than 1hectare in Flood Zone 1 and where significant flood risk issues occur at an individual development site due to localized drainage problems.

The law requires a “Sequential approach” to site selection. You must legally pass the Sequential Test, proving no lower-risk alternative sites are available. If required, the Exception Test must then demonstrate the project provides sustainability benefits and remains safe for its lifetime.

In addition to satisfying these tests, developers of major developments must use Sustainable Drainage Systems (SuDs) as part of the design process to mitigate the potential risks associated with surface water run-off.