Residents must be protected from extraneous noise so that they can sleep, rest and engage in normal domestic activities. Such noise may be due to external sources such as aircraft, traffic or nearby industry; it may also take the form of airborne sound originating with neighbours. In the case of flats, it may be structure-borne impact sound originating with neighbours on an upper floor.

Airborne Noise from Neighbours

The Building Regulations recommend various forms of party wall and flooring which, when tested, achieve a minimum weighted standardised noise level difference (DnTW+ Ctr) of 45dB between neighbouring premises. 

According to the Construction Industry Research and Information Association's report ‘Sound Control for Homes’ (1986), external walls typically reduce outside noise by 34dB(A), though by increasing their specification this can be improved to 40dB(A). Designers should aim to increase the specification of party walls permitted by the Building Regulations so that their performance is equivalent to that of a detached house. It is also prudent to zone the rooms of adjoining houses so that, for example, living rooms, stairs and toilets do not abut neighbouring bedrooms

Impact Sound from Neighbours

Building Regulations recommend various forms of party floor construction for dwellings which, when tested, achieve a minimum weighted standardised impact sound pressure level (L1nT,w) of 62dB. Clearly, there is more limited scope here for improving the specification so that performance is equivalent to that of a detached dwelling. The need to zone the rooms of dwellings to avoid incompatible juxtapositions is therefore even more crucial.

Internal Airborne Sound

To ensure privacy, the Building Regulations require sound insulation of 40 RwdB between any room containing a WC (except en suites) and habitable rooms, as well as between bedrooms and other rooms.