Lisburn and Castlereagh, Castlereagh
BT27 4AS in Castlereagh has a Very low flood risk. Heat risk is Lower, with a median (50th percentile) of 4 days above 25°C per year, averaged over the 2021-2040 period under the RCP8.5 high emissions scenario (Met Office UKCP18). Air quality is Low at PM2.5 5.1 μg/m³, above the WHO annual guideline of 5 μg/m³ (Defra UK-AIR). Ground conditions are Low risk, with Glacial Till geology; shrink-swell risk is classed as improbable (BGS GeoSure).
Postcode-level flood risk data for Northern Ireland (DfI Rivers) is not yet integrated into LocalRisk. To check the specific flood risk at BT27 4AS, use the NI Direct flood maps. Heat, air quality and subsidence figures for BT27 4AS on this page are based on official UK sources and are postcode-level.
Air quality at BT27 4AS is rated Low, based on Defra UK-AIR annual mean PM2.5 data. Fine particulate matter (PM2.5) comes primarily from road traffic, industry, and domestic burning. Long-term exposure above the WHO guideline of 5 µg/m³ is linked to respiratory and cardiovascular health risks. Buyers and renters in higher air quality risk areas may wish to consider whether the property is near busy roads or industrial sources.
BGS GeoSure data classes the underlying soil at BT27 4AS as Glacial Till, with shrink-swell hazard rated improbable (subsidence risk band: Low). Soil type and shrink-swell behaviour drive subsidence claims following dry summers; recent ABI data shows insurer payouts rose sharply after the 2022 and 2025 hot summers. A structural survey is the reliable way to assess ground risk for a specific property.
This LocalRisk report for BT27 4AS draws on official UK open data sources: Met Office UKCP18 climate projections, Defra UK-AIR PM2.5 monitoring, and British Geological Survey GeoSure subsidence mapping. Postcode-level flood data for Northern Ireland (DfI Rivers) is not yet integrated. Risk ratings are a screening tool, complementing - not replacing - the searches and surveys ordered as part of a property transaction. Data covers Lisburn and Castlereagh and is updated as new official datasets are published.
Lisburn and Castlereagh has a mixed suburban and rural setting with river valleys, upland fringes and expanding towns and experiences cool, wet winters and mild summers, influenced by Atlantic weather and varied terrain.
Climate risk can change street by street, so it is worth checking neighbouring postcodes too. The full risk report for BT27 4AA is at localrisk.co.uk/postcode/BT274AA, and you can compare BT27 4AS side by side with any UK postcode at localrisk.co.uk/compare.