I am just about to install a bath screeen, of the type that has an aluminum channel fixed to the wall and the screen is screwed into this. All the information and instructions that I can find say that a bead of silicon should be run up the outside of the screen only - definetely not the inside. Why is this? Surely if the inside isn't sealed then water will become trapped between the channel and the wall and allow mould to grow?
I can understand where you're coming from, fc, and it appears to be the logical conclusion, but in practice it's definitely advisable to only seal on the outside. The reason being that any water that may get behind the profile can easily drain down towards the bottom of the screen and flow into the bath. I suppose the vertical section wouldn't cause any problems if silicone is applied to the inside edge - i always run a thin bead on the back before fixing anyway - its the horizontal bit at the base that should be left alone so that any water can get out.
I have a Kudos screen and the instructions were to seal the outside vertical and horizontal, and the inside vertical only. Like longboat says you leave the horizontal inside so any trapped water can work its way out.