Updates to the Planning Practice Guidance (PPG) 25th August 2022
The largest overhaul of the PPG Flood Risk and Coastal Change since publication, changing everything from functional floodplain definitions to building lifetimes and sequential test requirements.
Major updates to the Planning Practice Guidance (Flood Risk and Coastal Change) have fundamentally affected planning applications in England. This overhaul of guidance has changed the policy interpretation and requirements for developments considerably.
What has Changed?
The short answer is that almost everything has changed in the PPG Flood Risk and Coastal Change, from functional floodplain definition to building lifetimes and applications of the sequential test. This is the largest overhaul of the guidance since its publication. It is worth noting that this change applies to England only.
Sequential Test Updates
The Sequential Test now seeks “to steer new development to areas with the lowest risk of flooding, taking all sources of flood risk and climate change into account.” The PPG now clarifies that the absence of a 5-year housing land supply is not a relevant consideration for the Sequential Test, and the site does not need to be within client ownership to be considered ‘reasonably available’.
Design Flood Definition
The PPG now states: “This is a flood event of a given annual flood probability, which is generally taken as: river flooding likely to occur with a 1% annual probability; or tidal flooding with a 0.5% annual probability; or surface water flooding likely to occur with a 1% annual probability, plus an appropriate allowance for climate change.”
Previously, the design flood definition did not include climate change allowances. Introducing surface water to the design flood definition enforces requirements to assess such events including climate change allowances.
Functional Floodplain Definition
The functional floodplain is now regarded as the 3.3% AEP, or 1 in 30 year event. Previously this was the 5% AEP or 1 in 20 year event. This has major implications for developments near watercourses.
Lifetime of Development
The latest guidance states non-residential lifetime depends on characteristics but “a period of at least 75 years is likely to form a starting point for assessment.” Previously, industry best practice applied 60-year design lifetimes to non-residential uses.
Safe Access and Egress
The latest guidance requires assessing the “ability of residents and users to evacuate before an extreme flood (0.1% annual probability of flooding with allowance for climate change).” Many flood modelling studies lack climate change impact assessments during the 0.1% annual probability event.
The guidance suggests developers may need to cover the full cost of any additional emergency services provision needed where impact cannot be wholly mitigated.
Off-Site Impacts
The PPG clarifies that void use below buildings should “not normally be relied upon” for floodplain storage compensation. It confirms floodplain storage loss is “less likely to be a concern” in areas with appropriate flood risk management infrastructure or where flooding sources are solely tidal.