Cwm Ciddy House, Porthkerry Park Road, Porthkerry Park, Barry Data via plota.co.uk

The Environment Agency flood map for planning. Homes in zone 3 must also pass the sequential test. Surface water flooding is a separate map.

Harm to a protected site is only accepted where there is no alternative and an overriding public interest.

Where development of farmland is needed, policy prefers poorer land over the best and most versatile (grades 1, 2 and 3a). Three sources: Natural England's post-1988 field surveys, which are definitive where they exist; the Defra predictive map for England (2025) and the Welsh Government predictive map, modelled from the soil map with 3a and 3b split; and the 1970s provisional map, which planners and other services still show, coarser and with grade 3 undivided. Where the provisional and predicted grades disagree, treat the predicted grade as the current estimate and expect an application to carry its own survey.

Nationally important archaeology protected by the Secretary of State. Work that affects the monument or its setting is rarely permitted.

Sites of special scientific interest are the best wildlife and geological sites in the country. Development likely to harm one is rarely permitted.

From the British Geological Survey and UK Health Security Agency indicative atlas. Under building regulations, as the BRE guide BR 211 (2023) sets out, new buildings and extensions need basic radon protection from class 3 in England and Wales and from class 2 in Scotland, and full protection from class 5. The class at the site itself, from the detailed BGS map, decides which.