Expert: Dan Griffin - 2/25/2008

Question
QUESTION: Hi Dan,
I'm remodeling my basement
The question I have is do I need a vapor barrier on my walls. I just framed it out and put insulation between the 2x4's. I did allow a little room behind my framing. I'm not going to use drywall. I put fearing strips perpendicular to the framing, so that I could put up barn wood from an old barn that I dissembled.
I live in the Chicago area and I do run a dehumidifier in the summer.
Thank you for your input
Larry

ANSWER: The conventional wisdom still puts the vapor barrier on the warm side of the wall.  If you used kraft faced fiberglass batts and you turned the paper to the inside of the room, you already have a vapor barrier.  I would not add an additional vapor barrier.  This assumes that you have dealt with cracks and water problems in the wall and that you have caulked / sealed / and plugged any draft points in the rim joist and plate area.

Some people hang a visqueen barrier, not as a vapor barrier, but to turn water to the floor in case the concrete has a problem.  This is often only half high, so it can't function as a vapor barrier.

---------- FOLLOW-UP ----------

QUESTION: Dan, I used John manville R-13 Formaldehyde free, mold and mildew resistant insulation. Is this kraft faced? If not I have a lot of 6mil poly should I put this over the fiberglass?
Thanks again,
Larry

Answer
Does the insulation have some kind of face? foil, paper, plastic all count: as opposed to being spun fiberglass batts only which are difficult to use in a one sided wall, but very common as sound batts and to install on top ceiling tiles.  Kraft face is an industry term for the brown paper face with the writing on it and the little flanges to staple it on with.

I doubt that your barn boards are going to lay up tight.  I am worried for you that the batt faces will show through the cracks, especially if they are tin foil or white.  Back when paneling was the thing, good practice was to use a black marker or flat black spray paint at the joints to hide the light color behind the joint.  Black Visqueen would work.