Housebuilders only have six months to prove to the government that their design details for separating floors and walls in new dwellings will consistently meet Part E of the Building Regulations – without the need for post-construction tests. If the government is unsatisfied with the details by the end of May, it will insist on testing a sample of new homes on every residential development, which could prove costly to housebuilders and potentially delay housing completions.
When the government published its proposals for changes to the Part E of the Building Regulations in January 2001, it said that acoustic testing would have to be carried out. After intense lobbying by the HBF, the government came up with a compromise: housebuilders could avoid this routine testing if they could come up with standard details that provided a "consistently good performance".
The steering group for the HBF Robust Standard Details project first met on 11 September to devise a timetable for the programme. Two months later working groups representing the masonry, concrete, steel and timber industries started submitting their construction details to the HBF. By 30 March 2003, each detail will have to have been tested 30 times to prove it is robust enough to be submitted for the government's approval.
The HBF has just revealed the fruits of its first two months of labour on its project website run by Napier University, which is managing the scheme. The first standard details put forward for testing by the working groups started appearing on the site this week. Information on the "Candidate" details includes drawings and instructions on how they should be constructed.
Among them are Candidates for timber floor constructions, steel composite systems and a cavity wall. The old standard cavity wall often had complaints due to poor mortar work on site. To reduce this risk and improve overall acoustic properties of the wall, the new Candidate RSD includes a render layer applied to the wall face. This seals the block face, joints and also improves the overall acoustic properties of the wall.
Project manager Sean Smith of Napier University says that most current separating timber floor constructions would not meet the new Part E requirements. The proposed Approved Document E only included one timber floor type (with independent ceiling joists). The Candidate RSD timber floors proposed avoid the costly expense of independent ceiling joists, according to Smith, and significantly improve the acoustic insulation performance.
Steel frame structures were not included in the proposed Approved Document E. The RSD project will include a timber of steel and steel–concrete composite systems, of which the latter perform very well for airborne sound insulation, according to Smith.
The tested RSDs have to be submitted to the government by 31 May 2003. Soon after that we will know whether the housebuilding industry has succeeded in its goal of self-regulation. With 1500 tests to be carried out on over 200 sites in less than six months, the housebuilding industry may require a bit of Harry Potter's magic to meet the deadline.