That is a bit drastic, have a search on here, the topic has been covered a number of times. The fault is often either the mastic seal between the outer sunroof surround and the roof, the rubber internal seal (vaseline helps) or the rubber drain hose connections to the internal gutter- the mastic breaks down on these.
Mine will be coming apart for an overhaul and fix in a few weeks (month or 2 at the most) will post the photos on here when done.