Are you supposed to put a vapor barrier on both sides of the common garage wall (wall between garage and house)

garageinsulation

In my garage, the wall between the house and the garage has visible studs and insulation in it. This insulation is 50+ years old and I am going to tear it out and put in new insulation.

My question has to do with the vapor barrier. I have always been told to put the vapor barrier on the "warm" side of the wall. This garage, however, has the studs, so I could only put the vapor barrier on the "cold" side of the wall (the garage side- not the house side).

For a common wall like this, with studs on the garage side, what should I do?

Location: Missouri

Best Answer

If you are insulating the walls with a Kraft Faced insulation then the paper side needs to be against the house wall. Regardless of any other insulation anywhere else in the garage, paper to the warm side always. If you are using unfaced insulation, then you probably won't get the vapor barrier you want and need unless you use foam board or closed cell spray foam. Putting the vapor barrier on the outside will cause condensation in your wall.