Advantages of cavity will over solid walls.
(i) When the outer leaf becomes wet, the space prevents water passing from the outer well to the inner wall, and thus the interior of the building remains dry which is not possible with solid walls.
(ii) The space will not allow heat to be transferred from one wall to the other. This arises from the fact that air is a bad conductor of heat and cavity acts as a barrier. The cavity therefore, is a good heat insulator and helps to keep the building cool in summer and warm in winter and this is not possible with solid wall.
