1.0 THE ASSOCIATION OF NOISE CONSULTANTS
The ANC was established in 1973 to represent the interests of noise consultants in the UK. Membership is on a company basis and since then it has grown to over one hundred member companies, including several international members and representing over seven hundred consultants.
Membership of the Association is open to all consultancy practices able to demonstrate the necessary professional and technical competence is available, that a satisfactory standard of continuity of service and staff is maintained and that there is no significant interest in acoustical products.
Members are required to carry a minimum level of professional indemnity insurance and to abide by the Association’s Code of Ethics. Members are consulted on impending and draft legislation, standards, guidelines and Codes of Practice before they come into force and have representation on many committees drafting these standards.
Membership of the Association is open only to those companies who can demonstrate they have the technical expertise to provide advice to clients, not merely testing services and companies which simply wish to undertake sound insulation testing would be unlikely to obtain membership. In this way the Association is able to ensure that expert advice is available to clients in the event of failure of a party wall or floor element.
The ANC Registration Scheme for pre-completion testing under Approved Document E: 2003, was established in response to this by members of the Association who were concerned at the cost and complexity of registration under UKAS, the only form of accreditation previously available.
Other areas of acoustic consultancy
Noise consultants provide advice on all aspects of noise and vibration. These include the design of sound insulation into, out of and between buildings, ensuring noisy plant doesn't annoy the neighbours and the noise and vibration impact of demolition and construction.
They work with planners to satisfy regulations relating to noise from roads, railways and airports, with architects to make theatres and concert halls sound good, undertake assessments of the noise impact of industrial installations including windfarms, petrochemical facilities and power stations.
They are involved with leisure noise including motorsport, pop concerts and even the noise from skateparks. This list is endless.
2.0 SOUND TESTING IN RESIDENTIAL BUILDINGS
A Brief History of Building Regulations
Building regulations have a long history, but the requirement for good sound insulation of walls and floors has a longer history than might be imagined. The earliest references are from ancient Babylon which are related to the structural stability of houses. The Babylonian ‘Law of Hammurabi’ is typically draconian:-
‘If a builder builds a house for someone, and does not construct it properly, and the house which he built falls in and kills its owner, then that builder shall be put to death. If it kills the son of the owner, then the son of that builder shall be put to death. ‘
After the Great Fire of London a Royal proclamation was issued and subsequently the ‘Fire prevention (Metropolis) Act of 1774 required buildings to have stone external and party walls. Again, whilst this is largely structurally related, they had an impact on the levels of sound insulation between properties.
In 1836 Professor Michael Faraday, who must have been a very busy man, turned his attention to the construction of prison walls. One must suspect, however, that this
interest was not so much about sound insulation as preventing escape! There are other historical references to ‘pugging’ in residential floors between working class houses in 1844, but specific consideration to defining actual levels of performance did not really happen until during and after the second world war.
In 1942 the ‘Committee on Sound Insulation and Acoustics in Buildings’ recommended a standard for party walls of 55dB and stated that a normal 9 inch brick wall provided about 50dB using the same metric. In modern parlance a 9 inch brick wall gives about 53dB:DnT,w.
In 1960 extensive measurements were carried out by the Building Research Station over 460 sites with many different types of constructions being tested. The Research Paper 33 – Field measurement of sound insulation between dwellings’ gave extensive test results.
These are still used today by acoustic consultants to establish the actual performance of some of the esoteric constructions which occur in building redevelopments where parts of the original construction from the first half of the 20th century are retained.
As a result of these extensive tests, ‘deemed to satisfy’ constructions were included in national regulation in 1965. Performance standards were first introduced as ‘Grading Curves’ Grade I and Grade II for residential accommodation in the Code of Basic data for the Design of Buildings: Chapter 3: Part 2: 1972 Sound Insulation and Noise Reduction. Based on social surveys and the measurements, Grade I was a level of sound insulation acceptable to the majority of neighbours for flats and houses and represented party walls with the performance of a 225mm brick wall. In the 1976, Part G of the Building Regulations contained actual performance requirements against different frequency bands.
Approved Document E [ADE] was first published in 1985 and contained performance standards and ‘deemed to satisfy constructions’ only for newly built properties. As a result of many complaints from the owners of houses converted into flats using the original Victorian timber floors as party floors during the 1980s, the next revision of ADE: 1992 contained performance standards and ‘deemed to satisfy constructions’ for converted properties, which was a major step forward for those living in flats. All of these revisions did not, however, have a requirement for pre-completion testing and relied on the inspections by Building Control to police the regulations.
The Need for Sound Testing in Residential Buildings
The previous versions of ADE were not in fact rigorously enforced by Building Control and as a result many properties with poor sound insulation were probably constructed. The lightweight floors (Type 3) and lightweight walls (Type 4), required careful construction and detailing to achieve the desired performance. But problems with even masonry walls
were quite common.
As consultants, only sites where there was perceived to be substantial problems were brought to our attention following complaints by residents. Some examples of bad
building are shown below.
3.0 PRE-COMPLETION TESTING 2003 TO DATE
Approved Document E 'Resistance to the Passage of Sound' of the Building Regulations was revised in 2003 and amended in 2004, including a new requirement to carry out precompletion sound insulation tests in a number of situations. This is currently only applicable to England & Wales.
The 2003 document required that any converted residential property whose registration with Building Regulations was after the 1st July 2003, would require testing to show that the required level of sound insulation was being achieved. The document indicated that 10% of all residences with the same construction should be tested or as otherwise directed by Building Control. Each property should have a ‘set of tests’ carried out. This means two party walls and/or two party floors. These tests should be for airborne sound in the case of walls and airborne and impact sound insulation for party floors between dwellings.
The ADE 2003 version also indicated that ‘Test bodies’ should preferably have UKAS accreditation. The ANC Registration Scheme for pre-completion testing was established in
response to this by members of the Association who were concerned at the cost and complexity of registration under UKAS.
In July 2004 newly built properties were included within the scheme which also applied to ‘rooms for residential use’ such as hotel bedrooms and residential accommodation in
student hostels, etc.
The Scheme was successful in securing approval from CLG (formerly ODPM), and is referred to in the 2004 amendments to the approved document to read, ‘The ODPM also regards members of the ANC Registration Scheme as suitably qualified to carry out precompletion testing.’.
The scheme also provides significant assistance to the building industry in authorising a considerable number of testers (currently over 300 and rising) to carry out these tests, who, would otherwise have no form of registration.
Reverberation in Common Parts
For the first time, the current version of ADE: 2004 requires assessment and control of the reverberation (echo) in common parts of a building. This means in corridors where there are a number of doors to adjacent flats or common stairwells which have doors opening onto landings, etc. From clarifications received from CLG it does not apply to stairwells or entrance halls which do not have doors to flats with direct access onto them.
The Robust Details scheme is an alternative to building under a pre-completion testing regime [pct]. Robust Detail [RD] constructions for floors and party walls have undergone rigorous testing to obtain RD status. If the residential party elements on a site are registered with RD then there is no requirement for pct. There are stringent controls and inspection at each stage of the constructions by those on site which are catalogued and there is a random inspection and testing regime carried out by RD Inspectors who are all practising acoustic consultants. We have six RD Inspectors at ASA.
Robust details are sometimes withdrawn if the inspection and testing regime finds regular faults on sites with their construction. By definition, the sound insulation performance of RD details is noticeably better than the ’minimum standard’ required by ADE.
EcoHomes and the Code for Sustainable Homes
EcoHomes is a version of BREEAM for homes. In 2007 EcoHomes formed the basis for the Code for Sustainable Homes for the assessment of new housing in England, Wales and Northern Ireland. EcoHomes has also been used for conversion projects but for new registrations has now been superseded in July 2011 by BREAM Domestic Refurbishment scheme.
The ANC are Not the Noise Police
Failures to achieve the minimum standard required by ADE 2003/4 are reported to the Client and not Building Control. This enables modification by the contractor and retesting to be carried out. As professional acoustic consultants ANC Registered Testers are able to give expert advice in relation to remedial measures following failures so that retests are likely to give compliance with the ADE requirements.
4.0 BUILDING CONTROL RESPONSIBILITIES
It is the responsibility of Building Control to require pct tests from the contractor so as to demonstrate that the ‘minimum standard’ required by ADE for airborne and impact sound insulation have been achieved.
It is the responsibility of Building Control to stipulate how many tests they require on a site. The number of tests quoted in ADE as 10% is a sensible compromise but fewer or more than 10% of properties with the same construction can be required and even tests on specific properties, specific walls or floors can be identified by Building Control if they so wish. Building Control may also insist that they witness the tests if they wish to do so. This level of involvement is, however, not usually exercised and the 10% figure as a minimum is followed by ANC testers.
If there are failures on a site Building Control can insist that any remedial works required on a plot to ensure compliance are also applied to all other samples of the same construction. They also have powers to insist on an increased number of tests following failures.
Ultimately it is the responsibility of Building Control to determine whether the dwellings on a site comply with the requirements of ADE.
5.0 ANC CERTIFICATE FRAUD
There are many incentives to comply with the required minimum standard required by
ADE. These include:-
• Avoiding the cost of remedial works which in some cases can be substantial, with the subsequent need to retest the walls or floors.
• Such remedial measures may have significant implications for the site programme.
• Sites may not obtain their EcoHomes or Code Points with implications for their attractiveness to potential buyers.
• Grants or funding from Housing Associations may not be forthcoming in the event of the properties not achieving the required performance
All the above factors may put pressure on site managers and contractors to achieve compliance.
Flattery by Imitation
As part of the ANC scheme, certificates are issued to Clients as part of test reports to confirm that walls and floors in a plot have achieved the required standard.
Evidence of forged certificate
Each valid sound insulation test certificate has a unique reference number provided by the ANC Registration Organisation. Each test company also has an organisation number. On the certificate above which was spotted by a watchful Building Control Officer, the organisation number does not coincide with the name of the test company. Organisation 164 is Sound Acoustics, not Philip Acoustics, the test reference number shown does not match either the test company or organisation number since it was carried out by PDA, another ANC member.
In response to this and several other cases of fraudulent ANC certificates, it was decided to create a verification system that could be used by Building Control to verify the test results submitted on line.
6.0 CERTIFICATE VERIFICATION
The ANC devised the ADvANCE system to allow the Client and Building Control to directly verify the results of tests carried out on a particular site. Certificates are no longer issued as part of the sound insulation test report.
Following site testing, the results including all the measured sound levels and calculations are uploaded onto the ANC website. The sound data is used for statistical analysis by type of construction shown in ADE: 2003, this enables ‘pass rates’ to be established for different constructions and overall pass rates to be calculated. An email is then sent to the ANC tester with a unique ‘Task Number’ and a ‘password’ to be issued to their clients for use on the ANC website www.theANC.co.uk . These details can then be transmitted to Building Control with Client approval so that they can access the test results on the ANC
The revision of the 1992 ADE version was long overdue, and it introduced pre-completion testing to ensure that residential properties and uses complied with the requirements.
The revision has given ‘teeth’ to the ADE regulations and after some initial teething troubles with the scheme, builders have responded very positively to the challenge. ‘Compliance’ rates for the properties tested are now more than 95% for the basic ‘minimum standard’ required by ADE.
Higher standards of performance are now rewarded by the points system associated with EcoHomes and the Code for Sustainable Homes. The performance standards of Robust Details are also generally significantly above the minimum standard, particularly for walls.
Is the ‘minimum standard’ required by ADE too low when the current market expectation is for better sound insulation performance?
8.0 THE FUTURE FOR SOUND & IMPACT INSULATION
It is widely recognised that the ADE basic minimum standard is not ‘fit for purpose’ under many conditions. Where the background noise is very low, such as rural areas or large housing estates away from transportation noise sources, the current performance requirements mean that even normal levels of speech can be audible between adjacent dwellings.
Some occupants of terraced or semi-detached properties are more sensitive to noise than others and their expectations of sound insulation and ‘peace and quiet’ is very high. Where there are adjacent dwellings with different lifestyles is often a cause of conflict, for example a young family above or next to an older couple without children can often be a source of conflict, even when occupants behave perfectly reasonably.
Research and the hundreds of thousands of tests carried out under the ANC and Robust Detail schemes have shown what can be achieved by careful and innovative design of party wall and floors. These constructions are enabling more points to be obtained for residential developments under the EcoHomes and now the Code for Sustainable Homes.
Does this indicate that the next revision of ADE will further raise the performance requirements for all residential developments
Watch this space!
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