We are re-modeling a small cottage in NJ and want to retain the appearance of the open beam and wood ceiling. We are considering 2″foam above the wood deck and then ply sheathing on top, covered with asphalt shingle.
My concern is preventing roof rot on the lower roof deck. Is there a way to prevent condensation using this system?
Bobalu
Replies
I would think putting a vapor barrier on the lower deck under the insulation would work. (At least in a climate where heating is your main concern--if you are using refrigeration ("air conditioning"), you may have condensation in the summer.)
Thanks for the come-back Danno.
Bobalu
You're welcome. You might check out a web site called "buildingsciences.com"--it tells a lot about insulation and vapor barriers for various climates. In NJ, you may not want a VB on either side of the insulation--let the vapor flow freely in and out. The problem I see is that depending on which foam insulation you use, it itself can be a vapor barrier. I think Dow Styrofoam is. I'm not sure about dense fiberglass panels.