Abstract: This study analyses the behavior of swelling soils when they are moistened under buildings and structures. The methods and principles used currently for the design of structure foundations on swelling soils involve important problems due to non uniform deformations of these soils when subjected to the structure loads. In order to avoid the negative effects of swelling soils and to reach the desired performance on one hand and the economical results on the other hand, the special computations of the foundations stiffness and deformability must take into consideration the prevention of the swelling soils feature and in some cases preserve it. The current study was elaborated in order to design flexible continuous footings on swelling soils taking into account the water content change on one hand and the contact pressure distribution on the footing on the other hand.