The measures, announced fewer than two months ago, will extend Part E to new building types and raise the standard of sound insulation for dwellings. The changes will affect designers, developers, builders and manufacturers and, according to DETR estimates, could add more than £2000 to the cost of a new flat.
The acoustic rules are being updated for two reasons: to tie in with the government's plan to make high-density housing a key element of urban regeneration, and in response to consumer pressure. In particular, it will help homes meet the requirement in PPG3 that "new housing and residential developments should be well designed". It will also bring Britain's acoustic laws more into line with the rest of Europe.
Under the changes, schools, hotels, hostels, student accommodation, nurses' homes and homes for elderly people will be covered by Part E for the first time. The DETR is looking to publish the revised regulations by early 2002; they would come into force six months later.
It is not just the scope of the regulations that has been increased; the government is also proposing to increase the sound insulation values of walls and floors. Surveys by BRE have shown that about 25% of occupants are dissatisfied with their current sound insulation, even when it has been installed correctly. The new standard aims to address this by increasing sound insulation values for floors by up to 4 dB, and for walls by 3 dB. It will also put more emphasis on low-frequency noise, such as the bass notes from music systems, which is the most difficult to eliminate.
To ensure that all homes have adequate levels of sound protection from adjoining dwellings, the proposed revisions contain explicit targets for sound insulation. These cover airborne sounds for walls and floors, such as noise caused by people shouting, and impact sounds on floors, such as footsteps.
Complying with the new standards will require changes in the way buildings are constructed. For wall construction, some types of lightweight blocks will no longer be recommended for loadbearing applications in flats. Instead, blocks with a minimum density of 120 kg/m3 will have to be used. And masonry separating walls, commonly finished using plasterboard, may now have to be finished with wet plaster. Cavity wall ties, too, have a new performance standard.
For floors, the implications are far-reaching. Beam-and-block floors are unable to meet the new performance standards and have been removed from the Part E guidance document. The DETR estimates that this alone will add up to £1500 to the cost of a flat. Timber-framed floors have also been redesigned and more guidance has been issued on the use of resilient layers and proprietary floating floors.
In a move that is proving controversial with housebuilders, the government will ensure that these targets are met by making builders pay for tests on dwellings to ensure compliance before completion. BRE estimates that up to 25% of separating walls and 40% of separating floors in new dwellings fail to meet current standards, before the increases proposed under this amendment are taken into account. The DETR predicts that the tests alone could cost more than £1000 a flat on smaller sites. And if the building fails the tests, remedial work will have to be completed by the builder, at its own expense, before occupants move in.
This requirement will hit small builders particularly hard – even a single pair of semi-detached houses will have to be tested. For larger developments, this requirement could be relaxed at the discretion of the building control body to include a typical sample of, say, one in every 10 dwellings constructed.
The standards will be particularly difficult to achieve where an existing building is being converted into flats. This problem is recognised in a clause that says builders will have to ensure that "as much as is practical is done". However, it has a sting in its tail: building control will assess the adequacy of the solution but, whatever the building's acoustic performance, the results will have to be declared to prospective purchasers. Even the corridors and stairwells of blocks of flats must now be treated to prevent noise echoing around the common areas.
Although most of the proposed changes apply to higher density developments such as terraces and flats, the proposal to increase sound insulation between rooms will affect all new developments, even exclusive collections of detached houses. To enhance privacy within a home, a new requirement to provide sound insulation between WCs and the other habitable rooms and between bedrooms and other rooms has been introduced. However, testing to prove compliance will not be required.
In addition to improving sound insulation between dwellings, the proposals include transferring responsibility for sound insulation to the building envelope from planning authorities to building control bodies. This will mean that sound insulation, thermal insulation and ventilation can all be considered together.
The changes to the acoustic regulations have been issued fewer than four months after a similar exercise was completed for the energy rules – Part L. However, the government has acknowledged that there is a conflict between the two documents, particularly in the use of lightweight blocks for walls. The higher density blocks called for under Part E have a poorer thermal performance than many lightweight blocks, so builders will have to allow for this by building walls with a wider cavity and increasing the thickness of thermal insulation within the wall.
In the light of this conflict, the consultation form for Part E will allow respondents to change comments made in the earlier consultation on Part L. But time is running out. If the industry does not like what it is hearing, and the indications are that it does not, it must start shouting now.
Changes at a glance
- Insulation standards have been raised to make homes quieter
- Explicit performance targets have been produced for insulation between dwellings
- The sound insulation of most new dwellings will have to be tested and remedial work completed before a home is occupied
- The regulations have been extended to include schools, hotels, hostels, student accommodation, nurses’ homes and homes for elderly people
- Sound insulation will have to be provided between a WC and habitable rooms; and between bedrooms and other rooms
- Sound insulation of the external envelope is covered for the first time
- Noise control measures will have to be installed in corridors and stairwells of flats
Part E: Resistance to the passage of soundPart E currently applies to the control of sound through separating walls and floors of dwellings. However, the DETR has issued proposals for significant changes (Changes at a glance). The revised regulations are due to be published by early 2002. The Approved Document does the following:
- Details types of wall construction and provides data on how to avoid sound transmission at junctions
- Provides guidance on avoiding sound transmission at junctions for the three main types of floor construction: concrete floors with a floating layer, concrete with a soft covering and timber-based floors with a floating layer
- Recommends the minimum mass for wall and floor constructions
- Provides guidance on testing the performance of walls and floors
- Provides guidance on typical floors and walls where an existing building is converted into dwellings.