The effect of neutral gas puffing in ELMy H-mode plasmas is studied us-ing integrated predictive transport modelling. Integrated modelling includes the plasma core, the edge transport barrier and the scrape-off layer and it is needed, because there is a strong link between these three regions. Self-consistent results are obtained by coupling the one-dimensional core transport code JETTO with the two-dimensional edge code EDGE2D. In addition, MHD stability analysis is performed on the output of the transport simulations. The results of the MHD stability analysis is used to adjust MHD stability limits in the transport modelling, so that there is a feedback loop between the transport codes and the MHD stability codes. It is shown that strong gas puffing causes a sequence of causalities involving edge density, collisionality, bootstrap current, total edge current and magnetic shear, eventually triggering a transition from second to first ideal (n = ·) ballooning stability. Qualitatively, the transition from second to first ballooning stability resembles the experimentally observed transition from type I to type III ELMy H-mode with the accompanying increase in ELM frequency and deterioration of plasma confinement. Furthermore, it has been possible to reproduce the mixed type I-II ELMy H-mode, as observed in experiments.