Two weeks ago the government moved to prohibit the use of multifoil insulation in roofs. They wrote to all the local authority building control departments and to bodies like the NHBC, concerned with the policing of our building standards, and told them that they could no longer accept the use of Actis Tris Iso Super 10 and similar products as an adequate method of insulating roofs. In future all insulation must meet the standards laid out in BR 443, requiring hot box tests to be carried out. Multifoils do not perform well in hot box testing and instead have relied on comparison testing, where the material is used head-to-head with other insulators in similar roofs and measurements are taken of energy usage.
Mutilfoils have had a very good run in the UK. Most other countries – at least the ones that take these things seriously — have given them short shrift. But Actis gained a toehold in the UK by gaining third party approval from BM Trada, who witnessed the comparison roof tests and verified that the performance of their multifoil was as good as 200mm of mineral wool. This test, carried out nine years ago, has been the subject of much heated debate ever since: there have been many sceptics who suggested that the mineral wool was pulled well and truly over the eyes of the witnesses. Yet, on this basis, Actis and others have sold hundreds of acres of their multifoil products. Builders like them because they are no more than 25mm thick and are very quick and easy to fix and are especially good in situations like loft conversions where headroom considerations make other thicker insulation problematic. And indeed, I have spoken with several customers who have been delighted with the thermal performance of their multifoiled roofs. But this doesn’t prove anything, as it is notoriously difficult to measure the thermal performance of just a part of a structure.
Aware of their precarious position, the multifoil suppliers formed themselves into a Confederation of Multifoil Manufacturers with a brief to persuade the powers-that-be that multifoils were as good as they claimed and not some elaborate con. They did very well. They were given an extension till Jan 1st 2007 to prove their case. But sometime in September, the position of the legislators hardened and this extension has been removed.