The Behaviour of Vapour Transfer on Building Material Surfaces: The Vapour Transfer Resistance

Abstract

While the consideration of the heat transfer resistances on surfaces is natural in practice, the similar effect of the moisture transport is not considered. New investigations showed that in some cases the transition resistance of vapour should not be neglected. Experimental studies have been carried out to determine the rate of vapour transfer at various surfaces. For the transition of vapour at different surfaces specific differences could be detected. A definition by cases concerning the involved surface must be made. This distinction can be met with the aid of the so called vapour transfer resistance, similar to the usual description of heat transfer. Appropriate numerical values are presented and discussed.