moisture barrier, or vapor barrier...the plastic mat that covers the openings in the door behind the door panel.. whatever it is called, i hope you all know what i am referring to. well, on my 96 sedan they have basically fallen apart over the years. i went to the dealership to order new ones and they are no longer made. 2 questions.

1. are they really necessary? i think i understand what they are there for.

2. what is a suitable replacement, just some plastic cut to fit?

 

I have use 6mil construction poly, [plastic] 94

 

You can use construction sheeting like fcm mentioned. Use 3M window-weld or some butyl adhesive caulk from a hardware store to seal the plastic to the door frame.

Another alternative is something like this.. How to install VB-2HD by Cascade Audio Engineering

 

awesome, thanks for the replies guys!