In some cases just leave it alone
July 25, 1980
Q. We've had cellulose insulation pumped between the floor joists in our attic. Since then people have variously been telling us: (1) We need a vapor barrier; (2) we should use glossy paint on the bedroom ceiling which is papered; and (3) we don't have to do anything. What do you say? Stephen J. Beecroft Winona, Ontario
A. If it were my house I'd leave it exactly the way it is.
An added barrier, such as an oil-based enamel paint on the bedroom ceiling, would thwart a certain amount of humidity, but the effect is likely to be minuscule.
After all, the fact that you already have many coats of paint, plus wallpaper , now on the ceiling, there is little in the way of vapor transmission into the attic.
My advice: Don't worry about it.