Sound classification of dwellings: Quality class ranges and intervals in national schemes in Europe

National schemes for sound classification of dwellings exist in more than ten countries in Europe, typically published as national standards. The schemes define quality classes reflecting different levels of acoustical comfort. Main criteria concern airborne and impact sound insulation between dwellings, facade sound insulation and installation noise.
The schemes have been developed, implemented and revised gradually since the early 1990s. However, due to lack of coordination between countries, there are significant discrepancies, and new standards and revisions continue to increase the diversity. Descriptors, range of quality levels, number of quality classes, class intervals, denotations and descriptions vary across Europe.
The diversity is an obstacle for exchange of experience about constructions fulfilling different classes, implying also trade barriers. Thus, a harmonized classification scheme is needed, and a European COST Action TU0901 "Integrating and Harmonizing Sound Insulation Aspects in Sustainable Urban Housing Constructions", has been established and runs 2009-2013, one of the main objectives being to prepare a proposal for a European sound classification scheme with a number of quality classes for dwellings.
However, each of the national classification schemes represents the result of extensive efforts, considerations and discussions, often during many years, and a change cannot be accepted easily. Thus, it is important to analyze present schemes and involve all countries in the preparation of a European proposal. This paper deals with the sound insulation between dwellings and focuses on comparison of range of quality levels in the national schemes, number of quality classes and class intervals.