Insulation, Radiant and Vapor Barriers - Two Different Rooms....Vapor Barrier Needed?

There's this room that we are insulating that is attached to the house. It used to be a garage, so the wall attached to the house was insulated with a vapor barrier toward the main part of the house, but the rest of the garage walls were not insulated. The main part of the house has/had a central furnace/AC with ducts and everything. Now the garage is a room, and it has it's own gas space heater, since no ducts can be tied off to the room. We are insulating all the walls, including replacing the insulation on the wall attached to the house for noise b/c they have different climates since the gas space heater won't always be on. The question is...I already bought five packages of unfaced r-13 insulation. Do I need to install a vapor barrier on this wall, or can it just be unfaced? (since it is not an exterior wall)? Thanks!

I know this topic has probably been discussed already...but i'm not sure if a vapor barrier is need if one side of the wall has an inconsistant climate while the other side of the wall has a constant climate (being an interior wall). Thanks!

A lot depends on where you are and what the climate is.

It may not make much difference if you are not in a harsh or extremely moist climate. This subject is very easy to over-analyze and "golden rules" like no double vapor barriers are not always correct. Your existing vapor barrier is probably compromised in some areas and may not be 100% effective anyway.

Remember - when your house windows are open and you are heating or cooling in the garage area, everthing is reversed between conditioned and unconditioned spaces. There are 100's of combinations to beat to death.

Dick

Well we removed all the insulation on that wall. There currently is no vapor barrier at at on that wall (there was one). Chicagoland here, it can get very muggy in the air during the summer.