The punching resistance of actual reinforced concrete flat slabs is potentially influenced by the compressive membrane action, which may significantly increase their resistance compared to isolated laboratory specimens. However, design codes have been developed using the results of laboratory experiments and therefore usually neglect this phenomenon. In this paper, a numerical model is presented to describe the behaviour of continuous and confined flat slabs under distributed loads. The flexural strength and stiffness are shown to increase due to the redistribution of moments and in-plane forces in the slab arising from the confinement of the slab dilation. The failure criterion of the Critical Shear Crack Theory is applied to predict the punching strength. The modelling results are compared to experimental data of some unconventional punching tests from the literature and satisfactory correlation is found.