89. There are no additional costs associated with Option 1 but it is felt that to 'do nothing' would contribute to a worsening of the situation for the reasons given in Section 7.1. An indication of the likely financial consequences resulting from the 'do nothing' option could be derived from the unrealised benefits associated with Option 3 that are discussed in Section 7.4.
90. In order to estimate the costs of Option 2 it is necessary to make a number of assumptions. For example, if £1million were invested to promote similar design guidance to that envisaged in the revised Approved Document then the cost of the enforcement regime would be avoided. However, in the absence of the enforcement regime then the rate of take up and rate of compliance with the guidance would be much less, perhaps say 20% of the industry would voluntarily improve standards and, perhaps 10% would comply with the intended standard. At first glance, costs would appear to have been reduced by approximately 80%. However the costs of the unrealised benefits have also to be included since 80% of new dwellings would not be affected at all by the adoption of Option 2, and a further 10% would not meet the intended standard. Further, the costs (and benefits) of Option 2 would be distributed in an inequitable manner both within the industry and within society since voluntary codes would not be followed by all.
91. Options 1 and 2 are not considered to be viable options for the reasons given above. Therefore this Section presents an estimate of the additional costs of Option 3.
92. The proposals discussed are wide ranging and would affect several sectors of the building industry including builders, developers, designers, manufacturers, and building control bodies. Some sectors would be affected by national sound insulation requirements for the first time, particularly those sectors covered by the definition of rooms for residential purposes (which include hotels, boarding houses, hostels, student accommodation, nurses' homes and elderly persons' homes). Charities would be affected in their role as social landlords and the effect of the new Requirements on the social housing sector has been specifically examined during the consultation period (see Appendix C).
93. The Small Business Service has been formally consulted. The impact of the amendments on small business has also been assessed during the consultation process. The amendments have received a mixed response from small businesses. Some consultees have welcomed the level playing field and quality assurance aspects of the amendments and commented that the move to a performance standards based approach would encourage the development of new techniques. A common concern was that small businesses would not be as aware of the risks involved in using certain constructions as larger companies and for this reason small businesses strongly support the collation and feedback of sound insulation test data to the construction industry. Some consultees have been concerned about the cost of the required changes in construction practice and the cost of the pre-completion testing regime and felt that this cost would fall disproportionately on small businesses. This issue has been examined during the consultation period and typical costs for small developments have been estimated and included in Appendix C.
94. As a result of the small business consultation exercise the operation of the pre-completion testing regime has been thoroughly reviewed by the BRAC Technical Working Party in order to try and reduce the burden on small businesses. This review has included consideration of alternatives to pre-completion testing, such as introducing robust details and using supervision from acoustic consultants.
95. The Working Party has also received improved information from NHBC and the House Builders Federation (HBF) regarding house types and typical site sizes and, as a consequence, has acknowledged that the costs of the pre-completion testing regime will be greater than at first estimated.
96. After considerable debate, the Working Party has endorsed the operation of a slightly revised pre-completion testing regime as detailed in Section 1 of Approved Document E and further recommended that the status and importance of pre-completion testing should be clarified. The reference to the need for pre-completion testing that was previously contained in Section 0 is now contained in a new Regulation. The Working Party has been unable to identify suitable ways of reducing the cost of the testing regime without compromising the objectives and has subsequently accepted a revised estimate of the costs involved.
97. Those who are affected by implementation of the amendments will have, as a non-recurring cost, to acquaint themselves with the new provisions and where necessary to invest in appropriate professional and technical training.
Requirement E1 - Changes resulting from the extended scope of Requirement E1
98. The main additional cost in this category of change would arise from the extension of the Requirement to cover rooms for residential purposes. There is little reliable data on the number of such rooms that are created each year. However it is reasonable to assume, in the absence of current guidance, that a large proportion of purpose built rooms for residential purposes will currently be designed to meet the current sound insulation standards for dwellings. Some such rooms, for example in modern hotels, will be designed to exceed current sound insulation standards for dwellings. The requirement will also apply to rooms for residential purposes created as a result of a material change of use. The number of such conversions is likely to be small in comparison with the number of new build dwellings, although numbers may grow as a result of changes in housing policy. In Table 4 an estimate has been made of the potential national cost to this sector on the basis that it is 5% of the total cost to the traditional dwelling sector (i.e. 5% of the £36 million estimate derived below) covered by the current Approved Document.
Requirement E1 - Changes to the structure and content of Approved Document E so as to improve sound insulation
99. Requirement E1 will only affect attached dwellings, i.e. semi-detached and terraced houses and flats. In order to calculate the overall cost of compliance representative models of these three house types were considered and the areas of separating floors and flanking and separating walls calculated. In the current and the revised Approved Document there are a range of constructions that can be used for each of these walls and floors and so the cost of building these constructions to the current and revised guidance were obtained from a quantity surveyor.
100. The frequency of occurrence of the construction types for separating floors and flanking and separating walls as specified in the current Approved Document were obtained from a survey of 27 large and small house builders. The builders surveyed are responsible for constructing over 36,000 units per year (covering both the private and social sectors) which is over 20% of the total number of houses built each year in England and Wales. It is therefore considered to be a representative sample.
101. The compliance cost for this category was estimated by calculating the cost of moving from the current range of common constructions to the anticipated new situation. A judgement was made as to the changes in building practice that would result from the changes to the constructions in the revised Approved Document. The compliance cost has been adjusted to reflect the true additional cost of improving standards because not all examples of current constructions meet the existing standards.
102. On the basis of this calculation it is estimated that the increase in wall construction costs for a typical pair of terraced and semi-detached houses is about £100. It is estimated that there will be no overall increase in the costs of wall construction in flats, because slight increased costs resulting from restrictions on the use of certain concrete blocks in flanking walls (the new Approved Document proposes a minimum mass per unit area 120 kg/m2) have been offset by changes in external wall design resulting from the Part L revisions. The estimated cost for floors in flats varies depending on the type of new construction chosen, the typical cost increase will be about £1,500 with a range of £500 to £3,000 per dwelling.
103. Another reason for these small cost changes is that the new Approved Document proposes an increased use of plaster finish to masonry walls, replacing the current widespread use of plasterboard. Research has shown that wet plastered walls have a better sound insulation performance compared to similar walls with a plasterboard finish. It is acknowledged that a wet plastered wall will require drying time, which may delay other trades (e.g. painters). However, the use of a wet plaster finish is cheaper than the use of plasterboard and is common practice in several countries.
104. These unit costs can be grossed up to a national level using DTI construction statistics on the annual rate of house building and NHBC data31 on the incidence of the different house types. The annual total cost for walls will be £5.5 million, and that for floors will be £27.1 million.
105. It is more difficult to estimate the cost of compliance in the case of those dwellings created as a result of a material change of use, because it will depend on the type of building being converted. If the current building already meets the new requirements then the cost of compliance will be zero. More commonly, the new guidance may result in a need to undertake some additional work above that required by the current Approved Document. In a typical house conversion this could involve, for example, lining flanking walls, which is estimated to cost about £380 per flat. BRE estimate that there are currently approximately 10,000 buildings converted a year. The national annual cost is estimated to be £3.4 million on an assumption that there would be, on average, 3 new dwellings created per conversion and that about 30% of these will require additional flanking treatment. Costs for rooms for residential purposes formed by material change of use are discussed earlier in this section.
Requirement E1 - Measures that improve compliance with the Requirements
106. The cost for these measures has been estimated primarily on the basis of the implementation of the pre-completion testing regime for separating walls and floors in attached dwellings. The regime was initially costed on the basis of just over 1 in 10 of new attached dwellings being tested together with an allowance for administrative costs. This estimated cost has been revised based on improved information received during the consultation exercise from NHBC and the House Builders Federation (HBF) regarding house types and typical site sizes. The information received showed that small sites, with between 2 - 10 attached dwellings, currently make up about 10% of the total annual build of new attached dwellings. The frequency of pre-completion testing will therefore be considerably higher than 10% on these smaller sites. The information received also showed that it is now more common for several different house types to be built on larger sites, which will necessitate an increased frequency of testing on these larger sites. Overall, the revised estimate is that about 27% of new attached dwellings will be tested under the regime.
107. In order to determine the probable costs of pre-completion testing to builders seven acoustic consultants were surveyed on their likely charges for carrying out the required tests. Based on this survey, and the new information received from NHBC and HBF, the weighted32 average cost of a set of tests for separating walls in attached dwelling houses will be about £260. In the case of flats, the weighted average cost will be about £840 where both airborne and impact tests are required on separating walls and floors and about £670 where these tests will be required on separating floors only.
108. The national annual costs can therefore be estimated to be £3.6 million for testing separating walls in attached dwelling houses, £2.4 million for testing flats with separating walls and floors and £0.6 million for testing flats with only separating floors. When combined with an allowance for the additional costs related to the administration and organisation of the testing this produces a total estimated annual cost for pre-completion testing of £7.1 million.
Requirement E2 - Protection against sound within a dwelling etc.
109. Standard representative housing models were used to determine the cost implications of Requirements E2(a) and E2(b), including models for a detached house and a bungalow. As before, unit costs were obtained from a quantity surveyor. It is estimated that the additional cost for walls between bedrooms and between bedrooms and other rooms will be small amounting to some £5 to £8 per dwelling. The additional cost for floors will be greater and will range from £170 to £300 per dwelling, on an assumption that the improved timber floor construction will be most commonly used. If the industry were to adopt concrete internal floors more widely then costs (and benefits - such as improved fire resistance) would be higher.
110. The national cost for Requirement E2(a) is estimated to be £1 million. This figure is the grossed up additional cost of improving the sound insulation of internal walls between bedrooms and between bedrooms and other rooms. An allowance had been made for the aspects of this Requirement that are already current practice based on an existing NHBC requirement (See Section 4.2).
111. The national cost for Requirement E2(b) is estimated to be £27.6 million. This reflects the fact that the whole of the first floor area (rather than just the bedroom floors) for every new dwelling (rather than just attached dwellings) will need to be improved in order to comply with this Requirement.
Requirement E3 - Reverberation in the common internal parts of buildings containing dwellings etc.
112. The cost of Requirement E3 has been estimated on the basis of assumptions about the layout of typical blocks of flats and the areas of entrance halls, corridors, hallways, stairwells and stair enclosures. An absorptive material, for example a proprietary acoustic ceiling, could be applied in these areas to control reverberation and representative prices were obtained from a quantity surveyor. On the basis of these assumptions it is estimated that this amendment will increase building costs by about £350 per flat. This equates to an annual national cost of about £8.1 million. In Table 4 we have also included an estimate of the potential national cost for rooms for residential purposes and material change of use on the basis of 5% of the total cost for flats.
113. The cost and benefit estimates presented above relate to current house building policies. As sound insulation problems of the type addressed by Requirement E1 occur only in attached dwellings and rooms for residential purposes, the costs and benefits depend on the number of attached dwellings and rooms for residential purposes being built each year.
114. As Requirement E2 relates to internal sound insulation, it is affected by the total number of units built, but is less affected by the mix of dwelling types. Requirement E3 applies to flats and similar accommodation and so is strongly affected by the number of flats being built.
115. Currently there are about 160,000 housing units built annually. However, because of the policies set out in PPG 3, the mix of attached, detached and flats is likely to change in the future. The ODPM Planning Directorate judges that the mix will vary between local planning authorities, depending on local circumstances, and they do not have numerical estimates of the future mix. However, the House Builders Federation (HBF) has prepared an estimate and the current mix and a future scenario anticipated by the HBF is set out below.
Type of dwelling |
Current (1999)33 % |
Future (2005)34 % |
Detached |
50 |
15 |
Attached |
35 |
42.5 |
Flats |
15 |
42.5 |
116. Clearly, the costs and benefits could be considerably different in the future under this HBF scenario.
117. For Requirement E1 the current building cost estimates given in paragraph 105 would be increased as follows:
118. For Requirement E2 the current building cost estimates given in paragraphs 111 and 112 would be increased as follows:
119. For Requirement E3 the current building cost estimates given in paragraph 113 would be increased as follows:
120. The cost of pre-completion testing given in paragraph 109 could increase from £7.1 million to £22 million under this HBF scenario.. However, if sound insulation performance improves as expected, it is likely that the frequency of testing will decrease to a low level with a proportionate reduction in cost.
121. The estimated increase in the numbers of attached houses and flats increase the potential for complaints about hearing noise from neighbours, and so increase the need for the amendments to Part E. Under the HBF future scenario the estimated benefits will increase as follows.
The annual benefits estimated by the method given in paragraph 84 will increase from £240 million to £408 million.
The annual benefits estimated as in paragraphs 85 - 87 will increase from £24 million to £40 million.
122. Under current conditions the annual total costs are about £82 million, with speculative benefits ranging from £24 million to £240 million. These are the figures given in Table 4. Under the HBF future scenario the costs could increase to £161.7 million while the range of speculative benefits also increases to between £40 million - £408 million.
123. The range of annual costs is therefore between £82 million and £161.7 million while the benefits are between £24 million - £408 million depending on assumptions made about the mix of dwelling types in any future scenario.
124. The range of the estimated annual costs to address the problems of noise in dwellings and other rooms used for residential purposes represents approximately 0.8% of the current total annual selling price of new homes in England and Wales.
31 NHBC. New House Building Statistics – Quarter 3, 1999
32 Weighted to take account of typical site size and the typical number of different house types per site.
33 NHBC. New House Building Statistics – Quarter 3, 1999
34 HBF. Private communication, November 2001
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