And suppliers whose products have been excluded from the DETR's construction guidelines are lining up to prove that their solutions should not be left out.
Dave Baker, technical director of the House Builders Federation, believes that the proposals are unfair. "The HBF has no adverse views about upping the standards," says Baker. "But the costs of the tests are onerous. Testing a flat surrounded by others could top £2500, and it's very inefficient to find out that the house has failed once you have built it."
Smaller developments will be most affected by the changes because at least one – and possibly all – homes on a site will have to be tested. On bigger sites, it will be at the discretion of the building control body whether to test all dwellings or just a sample. This worries Baker: "When you're buying land, you won't know how strict the local building control will be and how much you will be charged for testing. So how do you know what the land is worth?" he asks.
Architect Stephen Prismall of Taywood Homes is less concerned about the statutory tests: "If you've got proper quality control, the tests are academic." But he says he would "rather spend the money on improving acoustic performance".
All the same, Prismall adds, the threat of remedial work stemming from test failures will compel housebuilders to comply with the standards. "From a commercial point of view, carrying out remedial work would be ruinous. We would seek solutions that met the requirements in the first place." The HBF's Baker agrees: "If you're testing completed units, what is the point of housing inspections?"
Ashley Love, technical director of Westbury Homes, is more positive about the proposals but he urges the DETR to be cautious. "Nobody's exactly leaping up in the air about the proposals but, if it's done in the right way, it will prove the integrity of the building," he says. "I think the DETR realises it's asking a lot. The enforcement of Part E should start in a low-level way to make sure the cost is kept to a minimum."
Westbury is about to start rolling out timber-frame homes from its Space4 factory and Love believes that changes to Part E and the energy regulations, Part L, will be easier to achieve with prefabricated systems. "Part E is just another factor that drives the investment in manufactured systems," says Love. He believes that if timber-frame housing is to meet the changes to Part E, "special attention must be paid to operational management and training" to ensure a high level of quality control.
One group of manufacturers that will benefit from increased use of timber- and metal-frame housing is plasterboard suppliers. However, their representative body, the Gypsum Products Developments Association, is unhappy about one aspect of the proposals. "It is disappointing to note that the document does not include many examples of framed construction solutions. This would appear to be at variance with the principles of the Egan initiative," says a spokesperson.
Another concern that may affect some manufacturers, according to Nick Antonio of Arup Acoustics, is that acoustic testing could have legal consequences for the builder, architect, subcontractor or material supplier.
"If homes being tested fail, who is liable and who will pay for remedial work? A few cases could end up in court," he says.
Aircrete manufacturers insist that they won't be picking up the tab, even though the revisions largely recommend blocks heavier than aircrete, with a minimum mass of 120 kg/m2 per unit.
Ian Exall, marketing manager at aircrete firm H+H Celcon, says aircrete block has better sound insulation properties than denser concrete and so does not have to have such a large mass. "We can meet the reduction in decibels using aircrete," he says. Exall's biggest gripe is that the proposed changes do not provide enough guidance on materials and give the impression that builders cannot use lightweight blocks. "On the face of it, the proposals would preclude our product," he concedes. But he insists: "The acoustic targets can be met with our products – we have an abundance of test data to back this up."
Paul Reed, marketing manager at aircrete block manufacturer Thermalite, is even more exasperated. "There aren't many aircrete examples in the proposals' guidance," he protests. "It's this discrimination we're a bit peeved about. We've done the tests and we know the product complies."
The DETR's Les Fothergill, who is responsible for the acoustic regulations, responds that the approved document is only guidance and does not preclude any material as long as completed homes meet the required level of performance. "Manufacturers would be free to produce their own guidance to illustrate ways their products can be used in association with other building materials to meet the standard," he says.
But Fothergill doubts whether builders would pass the acoustic tests if lightweight blocks were used in apartments. "This is because flanking sound transmission (in this case, along the inner leaf) is more important in flats, so more robust measures are needed to control it."
Exall says wait and see: "We are relatively confident that test data (particularly site test data) will show that it will still be possible to build flats with aircrete blocks."
Thermalite's Reed is dismissive of the tests the DETR is proposing: "Rather than meeting compliance through material tests, you've got post-construction testing. Even if blocks with a mass greater than 120 kg/m2 are used, the house will still fail the acoustic tests if it is constructed badly. You could build with paper and feathers as long as it works," he says indignantly.
In the long run, though, Antonio thinks that the proposed changes will be beneficial to the industry. "Nobody gets any feedback at the moment. You have no idea whether the workmanship is any good. At the very worst, it will reveal how badly we're building homes. But at its best, the proposals will help to trip up the bodgers and level the playing field," he says.
And of course, housebuilders will not be bearing the costs of those tests for long. As Antonio says: "The costs of increased sound insulation will be passed on to the buyer and homes will be more expensive as a result."