Standards for slates

Sirs;

We read with interest your page 2 article in this week's CJ, regarding the slate roofing problem at The Glades Shopping Centre, Bromley. It clearly illustrates a problem with slate specification, with no clear solution in sight.

STATS have been involved in several cases disputing the suitability of slates for given projects. In these cases product evaluation is difficult due to the poor specification requirements of the relevant British Standards (BS 680). The standard is inadequate for purposes of conformity and specification, but few suitable alternative standards are available. The draft European standards for slate have increased the tests but may be relaxing the pass/fail criteria. The problem of pyrite reactivity, which appears to be the cause of most of the perceived slate problems, is not addressed by any of the standards.

Lack of standards is a problem with many stone products, particularly dimension stone.

We would like slates and dimension stone to be as well specified in British standards as other construction materials, then specifiers and producers could be sure of a quality product, and scientists can evaluate product conformance with greater confidence should disputes arise. We believe this would eliminate costly legal battles such as that outlined in your article.

Terho Wilson

Quality Manager

STATS QA Ltd