Door Water Dam (Vapor Barrier)

[vettenuts]

Getting ready to install the Steiger Performance window regulator part and have been reading up on the door disassembly and reassembly. There is a water dam or as some call it vapor barrier under the trim panel. Service manual states to make sure it seals good. Is this part normally replaced when disassembled?

I have a BMW and this seal is critical to the door not leaking. If that barrier doesn't seal perfectly the water comes right into the car. Is it the same on the Jeep as well?

 

[tjkj2002]

Never had any water come into the cabin and all 4 of my doors have not had those barriers for 11 years now.Trashed them when I disassembled my KJ for paint way back in '02 when it suffered major hail damage.