In the framework of the dwarf nova thermal-viscous disc instability model,
we investigate the combined effects on the predicted dwarf nova lightcurves
of irradiating the accretion disc and the secondary star and of evaporatin
g the inner parts of the disc. We assume the standard values of viscosity.
We confirm the suggestion by Warner (1998) that the large variety of observ
ed outbursts' behaviour may result from the interplay of these three effect
s. We are able to reproduce light curves reminiscent of those of systems su
ch as RZ LMi or EG Cnc. We can obtain long lasting outbursts, very similar
to superoutbursts, without assuming the presence of a tidal instability.