I am tearing down the tile and greenboard above my bathtub because it was old and falling apart. One of the walls is an exterior wall and had a vapor barrier behind the greenboard. It had a little mold on it so I tore down the barrier around where the tile was (roughly 3'x6'). I live in Michigan, so this vapor barrier is there for the winter, not the bathtub/shower.
1) I am waterproofing the new concrete backerboard with Redguard. Do I need to replace the vapor barrier I removed?
2) If so, can I just replace the barrier where I tore it out?
3) Is there going to be an issue having the Redguard on the backerboard with the barrier behind it?
FYI, I am REALLY trying to avoid the answer of: tear down the entire wall and replace the barrier.
The V barrier does need to be replaced because it protects your insulation from moister within the house, and it needs to be a continuous (unbreached) barrier in order to work properly. However you don't necessarily need to replace the entire barrier in the wall. You can make the repair with Tuck tape (tuck tape a patch to the existing barrier). Just make sure it's a complete seal to the original barrier all the way around the perimeter of the patch. You may have to cut back a bit more of the drywall to expose the existing barrier.