§ Ms Rosie WintertonTo ask the Secretary of State for the Environment, Transport and the Regions if he will make a statement on the review of the conclusions of the report of the Expert Group on Thaumasite. [119400]
§ Mr. RaynsfordI am today publishing, on my Department's website, the review undertaken by Professor Leslie Clark of the conclusions of the report of the Expert Group on Thaumasite which he chaired and which reported in January 1999. When I announced the publication of the report last year I said that I had asked Professor Clark to review its conclusions in a year's time in the light of the findings of further research and monitoring which was then being commissioned.
The review found that the recommendations of the Thaumasite Expert Group's report were robust and continue to minimise the risk of the thaumasite form of sulphate attack in new construction. The report has been generally well received by the construction industry and is viewed as sound and well balanced.
There have been 20 new cases of the thaumasite form of sulphate attack identified in the last year. All of these have taken place in conditions that were anticipated in the report. None have posed any threat to public safety.
The new data available do not permit relaxation at present of the report's recommendations with one exception. There is a majority view within the Expert Group that the report's very conservative procedure for assessing the sulphate class of sulphide bearing ground can now, with safety, be relaxed somewhat in respect of pyritic clays. The review has also suggested the need for clarification of some aspects of the guidance given in the relevant BRE Digests and British Standards.