§ Miss Melanie JohnsonTo ask the Secretary of State for the Environment, Transport and the Regions if he is now in a position to report on the further research his Department commissioned on galvanised steel wall ties. [93805]
§ Mr. RaynsfordThe then Energy Efficiency Minister announced on 19 January 1998,Official Report, column 374, that as part of my Department's ongoing programme of research into rain penetration of cavity walls, she had asked for precautionary checks to be carried out on the condition of galvanised steel wire wall ties in a sample of houses with cavity walls filled with insulation. This followed the preliminary results of research at the BRE which indicated that there was a possibility that the life expectancy of green coloured galvanised steel wire wall ties might be shortened when used in conjunction with urea formaldehyde from cavity fill.
These checks have now been completed along with further experimental research and an independent review of the findings.
In the houses examined, there was no premature deterioration of galvanised ties with or without the green identification film in contact with urea formaldehyde foam cavity insulation.
The further experimental research was carried out on galvanised ties with and without the green identification film. The research comprised accelerated corrosion tests and chemical interactive tests with urea formaldehyde foam. Neither of these experiments indicated any discernible loss of galvanising.
With these results to hand and with the benefit of an independent review undertaken by consultants WS Atkins, BRE re-examined their earlier experimental findings. They have concluded that the accelerated corrosion observed under the experimental conditions could have been caused by vapour from the urea formaldehyde which under certain conditions of very high humidity can lead to very high rates of corrosion of galvanising. The conditions under which this could happen were present in the preliminary experimental research, but were unlikely to occur in houses.
The work concludes that there is no evidence that urea formaldehyde foam cavity wall insulation shortens the lifetime of galvanised wall ties.
Copies of these results have been placed in the House Library.