ABSTRACT
Performance of the WRB 2 cannot be considered in isolation from the cladding system with which it is used, nor can the cladding system be considered in isolation from the nature of the whole wall assembly. Yet, to discuss performance of WRB in the system we need first to be able to characterise the material alone. In this paper, therefore, we take a step back and introduce the material classification and performance characterization in respect to the field performance of the WRB products. The prime function of a WRB is to shed water that may penetrate the cladding. A secondary function includes the reduction of airflow through walls, while allowing the water vapour to escape from the inside of the wall. One could therefore think that the test methods used for determination of critical material properties such as air, vapour, and liquid permeability coefficients for these materials are not questioned. Yet, this is not the case.
This paper, second in the series, reviews the results of hygric tests conducted on various fresh and weathered WRB products. At this stage, the work did not aim at evaluating performance of the WRB products under various climatic conditions, but rather at examination of utility of new evaluation methodology that is proposed here. This evaluation methodology is for generating information on the basis of which such judgments might be made in the future.
