Insulating walls without an exterior vapor barrierr
I have a 1930s seasonal camp in Limington, Maine. Open studs on interior walls. Cedar clapboard exterior siding over T&G pine sheathing. No paper (or other vapor barrier) between exterior siding and sheathing. Siding and sheathing in good condition. Want to insulate exterior walls to extend seasonal use of camp - but concerned about lack of vapor barrier. Is it safe to install paper-faced fiberglas insulation on the exterior walls to be later covered with pine paneling? Thanks for any advice you can provide.
Re: Insulating walls without an exterior vapor barrierr
In cold weather climates, the vapor barrier is put directly behind the interior drywall or sheathing. The idea is to keep interior generated water vapor from being able to enter the wall cavity. a vapor barrier on the back side of the exterior sheathing would have the effect of trapping moisture in the wall cavity.
The best vapor barrier would be heavy plastic directly behind the drywall or paneling, with an absolute minimum of holes in it for such things as electrical outlets. All the seams in the plastic vapor barrier should be taped securely.
As your house is only used intermittantly, I think that the simple kraft paper type vapor barrier over fiberglass would generally be sufficient. You might want to use the plastic in high humidity areas such as in the baths or kitchen.