House built in 1996, so smack in the middle of maybe it contains asbestos, maybe it doesnt

. I noticed tonight that the plaster is damp. I know the damage was due to a previous leak, however I've only just noticed it's from the bath. The leak is not the pipes, but at one end there's tiles to make up the gap between the bath and wall and I believe water is getting down there. I'm going to blitz it with silicone (neatly), however I noticed the spot that is damaged downstairs is the joint between 2 pieces of plasterboard, but the floor above has been removed for pipe access so a few reasons why it's a problem. My aim it to seal the inside of the joints in the plasterboard with silicone (am also tempted to smear some all over the plaster oars, not just at the edges as well).