Further analytical studies of building cavity moisture concentrations.

The model of moisture concentrations in a building cavity containing hygroscopic material presented in earlier works is extended to allow for evaporating surfaces within the cavity (eg soil, water tanks) and fluctuating external climatic conditions. Linearized coupled differential equations are solved for three cases - 1. Steady state 2. Step function 3. Periodic climate driving forces. The third case gives formulae predicting the cavity moisture contents at any time of day or year, and shows that the steady state approximation is adequate for all but the tightest cavities. Field results give good agreement with model predictions.