Vapour permeability: Suitability and consistency of current test procedures

Abstract

The avoidance of condensation problems in the future depends on designers having available accurate and reliable vapour permeability values. The emergence of free trade within the European Community requires the transferability of measurement data between countries, as well as between individual laboratories. This paper describes a recent European intercomparison carried out to assess the comparability of existing permeability measurement techniques, and to provide the information required to enable future international standards to be properly formulated. Identical samples of two materials were tested by eleven laboratories covering thirteen European countries. At the beginning of the project detailed instructions were issued on all aspects of the test procedure. Even with such an approach, many of the participants failed to comply with all of the test requirements, and the data produced exhibited unacceptably large variations between laboratories. The major contributory factors for this are discussed, and recommendations on a possible approach to the development and implementation of a future international test standard presented.