I am sure your readers would be interested to know that recent claims by Dupont for its Tyvek product have resulted in two complaints upheld by the Advertising Standards Authority (14.1.04).
SureVent, the industry's roof ventilation watchdog, has been concerned for some time about advertisers promoting vapourpermeable membrane (VPU) products in a way that confuses and undermines the guidelines of BS5250:2002.
The first adjudication against DuPont said 'that the advertisers had not demonstrated that their products were BBA approved for all roofs on all types of buildings'. The second adjudication agreed that the claim 'meets BS5250' was misleading, because this is not the case.
Many SureVent members manufacture and promote VPUs in a responsible manner. It is imperative that the BS5250 guidelines are kept and that VPUs are installed with due attention to the manufacturer's instructions.
Whatever previous impression has been gained, a sealed ceiling must be provided and the batten space must always be positively ventilated when not ventilating the loft space. Depending on natural ventilation through the roof tiles is a strategy that does not work in the long term. Illustration of this is just smoke and mirrors.
Roof condensation is dangerous and must be prevented.
Ken Hamilton, the SureVent Campaign for Good Practice in Roof Ventilation