door vapor barriers...necessary?

["supermattthehero" <supermatty@xxxx>]

Hi there,

In the midst of a day-project adjusting my door latches and locks, I
removed the plastic vapor barriers from both doors. Now it's time to
put the door back together and it seems as though the sticky stuff
that was holding it on is no longer sticky. How necessary are these
things? I don't plan on ever driving my car in the rain, and my door
trim panels are all backed with plastic (not cardboard like some cars
which I understand could warp from moisture). 

So how necessary are they, and if they are necessary, what is the
sticky stuff called that I would need?

thanks,

Matt
#1604