[swamptiger]

I would install the vapor barrier in the ceiling (on the underside of the rafters)after installing unfaced roll insulation between the rafters. Then I would use several inches of blow-in fiberglass over the top of the rafters to seal the leaks and add further insulation. And make sure the attic is very well ventilated. Ventilation helps both summer and winter.

The old-timer might be right about the moisture moving out of the house through the attic vents, but I would rather not put any moisture there to begin with. Moisture is not a good thing to have in your insulation. And in colder climates where you are heating the house at least half of the year, I don't see the harm in having the moisture in the living area, because things tend to dry out anyway.

If you have soffit vents - buy the molded foam inserts to place above the wall plates to keep the air moving in from the soffits - "proper vents" - I think they are called..

 

[swamptiger]

I thought I would renew this thread because of a story I heard yesterday. There is a new home being built in our neighborhood whose builder can now really relate to the importance of installing a vapor barrier in the walls after installing insulation.

Well, this particular builder neglected to install the vapor barrier promptly after installing fiberglass batts in the walls a month or so ago. The home is being heated on a daily basis by portable heaters as the work progresses. The outside temperature here has been hovering in the teens & twenties, and dipping down to zero occasionally at night. A couple of days ago it was discovered that moisture had been accumulating on the inside of the outside sheeting all over in the house, and had actually started to mold in places already! So now, all the wall insulation has been removed, and they are trying to dry up the moisture. :no: :no: