RBWM Local Plan Update: Key Changes to Flood Policy
The Royal Borough of Windsor and Maidenhead replaces Policy F1 with NR1, removing the long-standing 30-square-metre extension threshold for flood risk assessment requirements.
The Royal Borough of Windsor and Maidenhead (RBWM) is implementing significant updates to its flood risk policies through a newly adopted Local Plan.
Policy Shift: F1 to NR1
The primary change involves the replacement of the long-standing Policy F1 with emerging Policy NR1. Policy F1, adopted in 2004 as Supplementary Planning Guidance, had governed flood risk assessments for development in RBWM for nearly two decades.
What Policy F1 Required
Policy F1 prohibited “new residential development or non-residential development, including extensions in excess of 30m2” unless proposals could demonstrate they would not impede flood water flow, reduce floodplain storage capacity, or increase flood risk exposure.
A critical aspect was the cumulative 30-square-metre threshold applied since 1978 — meaning previous extensions counted toward triggering policy requirements.
Policy NR1 Changes
The updated Policy NR1 maintains flood risk assessment requirements for developments in Flood Zones 2 and 3 but removes the 30-square-metre constraint entirely. Development must still avoid materially impeding water flow, reducing storage capacity, or increasing flood risk through new or exacerbated flooding problems.
An independent planning inspector recommended the Borough Local Plan for adoption on 26 January 2022, with formal adoption occurring on 8 February 2022.