When I removed my door panels to work on the windows, the VB was rather brittle and torn in some areas. I replaced it with plastic that I found at Lowes. Its pretty strong stuff, but to make sure it never ripped, I put duct tape on all 4 sides of any hole that I had to cut for door handles, cables, etc.

While I was in between stages on the window fix, I decided to give the VX a good washing. You would be surprised how much moisture gets through when there is no vapor barrier. I also had the door panels off so water got further, but I can only imagine how bad it would get with water getting in and getting humid.