The acoustic rules, contained in Part E of the Building Regulations, 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 new homes meet the requirement in planning policy guidance 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.
Part E applies to dwellings built in England and Wales – Scotland and Northern Ireland may issue separate proposals. 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 deadline for industry comments on the proposals is 20 April 2001, and the DETR is looking to publish the revised regulations by the end of the year. 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 the BRE have shown that about 25% of occupants are dissatisfied with their current standard of sound insulation, even when it has been installed correctly. The new standard aims to address this problem 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 both airborne sounds for walls and floors, such as noise caused by people shouting, and impact sounds for 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 mass 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 just as 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 move 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 bound to prove controversial with housebuilders, the government will ensure that these new targets are met by making builders pay for for tests on dwellings to ensure compliance before completion. The 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 estimates that the cost of the tests could be more than £1000 a flat for builders on smaller sites. And if the building fails the tests, remedial work will have to be completed by the builder, at its expense, before the 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 new 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 and disturbing residents.
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 have the advantage that sound insulation, thermal insulation and ventilation can all be considered together. It will also help address the requirement in PPG3 for more intensive housing development close to public transport routes.
The changes to the acoustic regulations have been issued less than four months after a similar exercise was completed for the energy regulations – Part L. However, the government has acknowledged that there is a conflict between the requirements of the two sets of regulations, 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.
How the proposals will affect housebuilding1 Timber floors will have to be redesigned to improve sound insulation.
2 Blocks with a minimum density of 120 kg/m3 will be required for the loadbearing masonry walls of flats.
3 Wet plaster finish will replace plasterboard and drylining for separating walls between dwellings.
4 Beam and block separating floors will not be permitted under the revised guidance.
At a glance
- Sound 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 any 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 by the regulations for the first time
- Noise control measures will have to be installed in the corridors and stairwells of flats
The industry has just three months to respond. The full consultation document Proposals for Amending Part E – Resistance to the Passage of Sound is available on the DETR website: www.construction.detr.gov.uk/coindex.htm