Dave Baker, managing director of Robust Details Ltd, looks back on a year of robust testing of Part E – and hopes that the scheme will be adopted for Part L

The principle of robust details was accepted as an alternative to pre-completion testing in new homes by regulations minister Phil Hope in January 2004. Accordingly, testing company Robust Details Limited opened for business on 4 May 2004, in readiness for the changes to Building Regulations Part E, the regulation governing acoustic performance in dwellings, which commenced in July 2004.

The aim of RD was to significantly improve standards of sound insulation while reducing the burden of pre-completion testing. The first edition of the RD handbook containing 14 key principles was published in May 2004. RDL was overwhelmed by the level of early support for the scheme – by the end of May 2005 more than 90,000 new homes had been registered with RDL and over 7500 handbooks had been purchased by builders, designers and regulatory agencies. These figures meant that those 90,000 homes would now be built higher than Building Regulations standards.

From the start, RDL monitored the performance of RD-registered new homes by carrying out field tests and inspections of work in progress. Due to the high level of early registrations, RDL appointed a number of acoustics experts to conduct the first batch of field sound tests on RD homes in the first quarter of 2004.

The RD inspectorate comprises 28 consultant acousticians, each of whom is allocated a geographical area and is given targets for checking new homes being built under the scheme. Their duties involve sample sound testing of RD homes, but at the early stages of the scheme they were asked to focus on visiting sites to make visual checks on homes under construction.

So far, feedback from the acoustic experts is very favourable about the general standard of construction and the high level of builders’ adherence to RD principles. As the system matures, RDL intends to commission sound tests on not fewer than 2% of all registered dwellings, with a further 1% of all homes to be subject to a visual inspection during the course of construction.

RDL’s decision to introduce visual inspections at the earliest opportunity has proved to be very useful in confirming that the scheme is delivering. The early start on field sound testing has also helped to confirm conformance - there have been no failures to date. Of the visual inspections 96% revealed no matters for concern or action. Where significant deviations from the RD scheme were observed full details have been passed to Building Control for action. A correspondence file on these cases is maintained at RDL.

by the end of May 2005 more than 90,000 new homes were registered with RDL and more than 7500 handbooks had been purchased

Deviations include such matters as the use of flanking structures not previously tested under the RD scheme, the inappropriate use of RD for conversions; and, in one case, the use of a solid masonry wall as a separating structure. Many of these deviations represent variations from specification that are unacceptable because the particular arrangement/configuration has not been tested by RDL (and therefore not covered by the RD handbook).

It is early days for RDL and there are a number of challenges still to be met if it is to meet all of the expectations of the housebuilding industry, its suppliers, customers and regulators, in securing high levels of compliance with the new regulations.

Nevertheless, RDL’s early commencement of performance monitoring, ahead of the anniversary of Part E on 1 July, has brought the inspectorate up to speed for what will be a very extensive programme of sound testing as the scheme moves towards maturity.

Additionally, RDL submitted a full response to the government’s public consultation on the proposed changes to Part L of the Building Regulations, focusing on the potential benefits likely to accrue if a RD approach was to be included in the new regulatory requirements. In short, RDL would like to provide an alternative to air leakage pre-completion testing, in much the same way as the scheme operates for Part E. RDL is awaiting further news on Part L and, in particular, whether it will be able to offer such a service to housebuilders.

New robust details

In the January 2005 handbook update, there were four new robust details and new options within some of the original robust details. A large number of other changes were made as a result of feedback and technical enquiries from the housebuilding industry and further field testing of houses and flats constructed since the original handbook was first printed. A number of candidate RDs are currently under assessment and some are likely to be published over the next twelve months, subject to their meeting the strict assessment criteria. These changes provide the housebuilding industry with more options for separating wall and floor constructions. Of particular note is the availability of new floors, significantly increasing the number of RD wall and floor combinations that can be used without any pre-completion testing.

Robust Details