Reading a noise map
The published contours describe outdoor noise from major roads, railways and airports. Day-evening-night levels include extra weighting for evening and night noise. They are not a reading inside a bedroom. No published contour does not prove a home is quiet; visit at different times and ask about glazing and ventilation.
Official services and sources
This site covers recorded homes in England and Wales. For Scotland use SEPA · Scottish EPC register. For Northern Ireland use NI flood maps · NI energy certificates.