Acoustic flooring standards for new dwellings have become much tougher. Alex Smith checks out the guidance and reviews BSI changes
The rules for the specification of flooring in new homes have been rewritten. New robust standard details drawn up by the House Builders Federation should soon see a big improvement in the acoustic standards of new dwellings. The RSDs are more complex than the drawings found in Building Regulation Approved Documents but the highly detailed guidance should eventually make specification more straightforward

and less risky.

New robust standard details

The RSDs were written in response to changes in Part E of the Building Regulations, which are intended to raise the standards of sound insulation in dwellings and habitable buildings. In the Part E consultation document, the government stated that all new homes should be tested to ensure they were complying with tougher standards. Housebuilders collectively balked at the idea. They claimed that testing would be expensive and time-consuming, and they feared having to carry out extensive work on hundreds of homes if sample dwellings failed testing.

After lobbying by the HBF, the government agreed to give housebuilders a year to prove that they were capable of building robust floor and wall details without the need for testing. The HBF has spent the past nine months designing and testing new separating wall and flooring details that they felt would comply with the tough standards.

So far, the HBF has revealed 13 RSDs, four of which are separating flooring details. These appear in a RSD consultation document that the government issued in August, and if the proposals remain intact, housebuilders will be able to use these RSDs from 1 January. If they don't, housebuilders will have to go down the testing route.

The flooring details represent three flooring types: concrete, timber and steel (see right). Each detail must be used in conjunction with a separating wall RSD as laid out in the robust standard document. The RSD programme is ongoing and there are more RSDs in the pipeline, including six flooring details: three concrete, one timber, and two steel. The programme also allows details to be submitted for inclusion in the future.

Each RSD is described on a six-page specification sheet and checklist. This includes the RSD's performance in decibels and guidance for the site workers as well as the specifier and architect. The advice is intended to prevent poor workmanship that may lead to the failure of the construction.

Each RSD also contains drawings (see diagram above) and notes on junctions between floors and wall types.

A checklist on the final page allows site managers to check the details have been constructed correctly.

Dwelling conversions and other habitable buildings such as hotels, hostels and student accommodation are not affected by the RSD programme and from 1 July this year had to undergo post-completion acoustic testing to ensure compliance with Part E.

Flooring RSDs

  • Concrete: precast concrete slabs
    Minimum 150 mm precast concrete slab, 65 mm, sand cement screed (or proprietary 40 mm) bonded directly to slab, concrete floating floor treatments 1, 2, 3, 4 or 5 (as described in RSD document) and one of three ceiling systems (1, 2 or 3 as described in RSD document).

  • Concrete: reinforced insitu concrete
    Minimum 250 mm reinforced concrete slab with a floating floor treatment (1–5) and minimum 75 mm ceiling void and one layer of gypsum-based board.

  • Timber: engineered timber I-joist
    Minimum 240 mm engineered I-joist, 15 mm sub-decking board, timber floating floor treatment 1, resilient metal ceiling bar and two or more layers of gypsum-based board (24 kg/m3).

  • Steel: insitu concrete on metal decking
    Insitu concrete slab, minimum 80 mm concrete cover to shallowest point, minimum 130 mm concrete cover to deepest point, using concrete floating floor treatments 1, 2, 3, 4 or 5, ceiling consists of one layer of gypsum-based board fixed either by timber straps, resilient metal ceiling bar or suspended metal frame ceiling.

    New standard

    BS 8425: 2003
    Code of practice for installation of laminate floor coverings. This British Standard gives recommendations for the installation of laminate floor coverings in new or existing buildings. Generally, laminate floor coverings are installed as floating floors but, in some applications, they can be integrally glued to the sub-floor. This standard only details suitable methods for floating floor installation and advises on the selection of materials required for their implementation. Price: £54, BSI subscribing members £27

    Recent standards

    BS 8203: 2001
    Code of practice for installation of resilient floor coverings. This Standard replaces BS 8203: 1996, which is withdrawn. Price: £74, BSI members £37 BS 5325: 2001
    Installation of textile-floor coverings. Price: £88, BSI members £44 BS 8300: 2001
    Design of buildings and their approaches to meet the needs of disabled people. A revision and amalgamation of BS 5619:1978 and BS 5810:1979, which are now withdrawn. Price: £164, BSI members £82 For a complete listing visit: HBF robust standard details project, visit: Online RSD consultation document, visit: