I've been reading last few weeks on proper shower wall install since mine leaked bad enough that I'm tearing it down to the studs. House is only about 15 years old but, IMO, improperly built like so many other tract homes. I'm discovering It's greenboard with no vapor barrier or waterproofing of any kind. At first I thought leak was from cracking grout, then running around the prefab shower pan and exiting the front where the shower door and curb are since there is no flange. I siliconed the wall-pan interface 3 years ago when I discovered a small leak, also tried to seal various shower door channels. Now, 3 years later and wiser, I think the combination of wall and all those channels/panels of the shower door was the bigger problem. Silicone on the wall bottom only helped trap some of the water running behind the wall from coming out while any water on the shower curb went straight out the side to the floor.

So I'm pretty much set on cement board and few coats of paint on waterproofing, reusing the plastic pan, but one thing I haven't seen addressed much is the shower door. I believe that is a big problem because any water that gets on the "threshold" channel may run straight into the wall and out the front, no matter how much waterproofing I have on the walls. And the only line of defense is silicone at the time of installation. I'm the kind of person that likes a physical barrier or redirection, not rely on cualk to keep water out. I feel no matter how well caulked, it's only a matter of time when water works its way to open up a gap since daily use by 2-3 people is a lot of use. It's not like I can check daily if there's water outside the shower. Everything is nicely hidden so I don't know failure until it's bad enough and there's evidence of damage. I think with the cement back/waterproofing paint I'm comfortable with the wall install, but how is a guy supposed to properly install a shower door and never worry about it?

Sorry for the long read, but I wanted to give some rationale on why I'm concerned about the shower door instead when there's so much discussion on the wall/tile itself.