Interstitial condensation: Applicability of conventional vapour permeability values

Abstract

Condensation is now one of the greatest building problems of this decade, and it is essential that the mistakes of the past are not repeated in the future. Accurate predictive techniques for interstitial condensation are now being used widely, but calculations are only as accurate as the input vapour permeability data. Although a considerable quantity of data are available, much of these are shown to be of limited use, only applying to the conditions under which the material was originally tested. The vapour permeability of plasterboard and plywood is investigated and a new approach to the presentation of vapour permeability data is suggested.