adding vapor barrier to existing metal roof

Clay Zimmerman
I have an existing wood frame metal building that was built without bubble wrap or any kind of vapor barrier under the roof metal. I now wish to put in a ceiling and blow in cellulose insulation. But what about condensation on the roof? I did not want to tear off the tin to put on bubble wrap and then reinstall it but one builder said the barrier needs to be right next to the tin. I was hoping I could tack up the barrier to the bottom side of the 2x4 nailers. this would give me a 1 1/2" air space. Can someone enlighten me? Yes, I know I do need to vent the attic space.
Todd Miller
Isaiah Industries, Inc.
A vapor barrier is a good idea and I do not see any problems with your planned placement of it.
Eric Novotny
An informed customer is the Best Customer!
Against the nailers or directly behind the drywall is fine.

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