I am remodeling my kitchen and am looking for advice on how to insulate the exterior wall. The house is located in Southern PA and was built in the late 40's. It is concrete block and previously there were just firring strips and (drywall/plaster) over it. I have framed out a wall in front of it so from the exterior working in there is stucco, concrete block, 3/4 in air gap and then 2x4 framing. How should I insulate this. HD and the building inspector recomended putting a 4 mil vapor barrier on the wall and then faced fiberglass insulation but that seems like a vapor barrier issue to me. I was also considering foam boards but am not sure. What about something like tyvek for the vapor barrier against the block wall so it can breathe some? I'm really not sure what to do here. A part of me wonders if it would just be best to leave it uninsulated (like the majority of the house). Please help asap I need to put the drywall up this weekend. Thanks.

You don't want any kind of vapor retarder on the block wall, and you certainly don't want two vapor retarders. House wrap on the block wall could act as a partial vapor retarder, trapping moisture from the house behind your new insulation and possibly supporting mold growth. You'll want to maintain a clear space betwen the inside face of the block and the back of the insulation as a capillary break, so that moisture in the wall doesn't soak the insulation, and the only vapor retarder should be on the winter warm side of the wall, right behind the wallboard. You have to count on the weather to allow any moisture that may enter the block to pass back to the outside.

Thanks Richard that is exactly what I wanted to hear and was where my current thought process was taking me. Your imput gives me some peace of mind.