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Part E: Resistance to the passage of sound: Floors

by John Boanson
Architect/ NBS Technical Author

Shrinking levels of building land available for development and the Governments push to utilise brown-field and infill sites are driving the increase in town houses and domestic flats construction. Planning Policy Guide Note 3 promotes development to a higher density. Fewer detached houses, more attached houses and flats gives greater potential for nuisance from noise from neighbours, hence the need for effective sound insulation. The majority of complaints to local authorities relate to sound.

In response to the above we have the 2003 edition of Part E, and for the first time, protection of sound within a dwelling house etc. has been introduced. Other new introductions are the Robust Standard Details and precompletion testing.

Floors, if they separate areas of different occupation are subject to both impact and airborne sound insulation standards, whilst those within a dwelling are subject to airborne sound insulation standards. The 2003 edition of Part E has adjusted indices to measure sound insulation making it harder to comply at lower frequencies (the frequencies that often cause annoyance from e.g. loud music). The target standards have been raised over the previous ones but are numerically lower because C_tr has been introduced into the values. C_tr is a negative number. It is this C_tr however that takes account of the lower frequencies.

Do you go for precompletion testing or do you use the Robust Standard Details of which there are at May 2006, only 10 examples for floor constructions? Whichever route you choose you will have to comply with the minimum standards laid down in Part E.

If you decide to go down the route of the Robust Standard Details do not think you will be saving money because you don't have to do precompletion tests. The RSD's are expensive constructions. If constructed correctly then floors can achieve sound transmittance values as low as 24 dB for impact sound whereas the maximum values allowed in Approved Document E are 62 dB and 64 dB. If you have a builder you have confidence in, then testing may be a cheaper alternative. If building a number of identical units and you opt for testing you may only have to test one in ten of the units whereas if you use the RSD's, they will have to be paid for for each of the ten units and you will be constructing an expensive construction ten times.

If you decide to go for performance testing then bear in mind that the tests are carried out when the building is virtually complete, so any remedial work could be awkward and disruptive to completion of the project.

It is the responsibility of the person carrying out the work to arrange the testing and liaise with the local authority about the frequency of testing. Achieving the required level of sound insulation is as dependant on the quality of building as it is on the detailed design.

Written February 2005

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