Position Control of Maximum Wetting Plane for Building Walls with Foam Polystyrene Heat Insulator

Current theory of moisture transfer, consisting in combined transfer of vapor in sorption wetting zone and liquid in oversorption zone, is reviewed. Moisture potential F, which is the basis for overwetting protection calculation of the enclosing structure, is described. A steady-stale problem on moisture distribution along enclosing structure thickness is presented. Expression for maximum wetting plane position assessment in the enclosing structure thickness is described. It is proposed to tie origin of coordinates and exterior insulation surface. “Relative shift of the maximum wetting plane” criterion is developed for the new coordinate system. Maximum wetting plane position for the enclosing structure made of aerated concrete masonry base and expanded polystyrene insulation is calculated. One parameter varied and others were taken as constant to find out dependences between maximum wetting plane shift criterion, layers thickness, and interior micro climate parameters. It is found out that increase in base thickness, temperature or relative humidity of inside air results in maximum wetting plane shift inside the enclosure, and increase in insulation thickness results in maximum wetting plane shift outside the enclosure.