Attic insulation should always be installed with the paper backing facing toward the living space the ceiling in this case.
Attic insulation vapor barrier direction.
This acts as a barrier to keep heated moist air from rising up into the attic during cold weather.
Since some leakage of moisture into the insulation in inevitable murphy s law you want it to be able to freely escape from the insulation into the attic.
Not be trapped inside.
Adding a second vapor barrier could cause condensation to become trapped in the insulation between the two vapor barriers.
In cold climates the opposite is true.
If the insulation is installed with the paper vapor barrier facing away from the heated part of the home moisture from humid inside air can condense and become trapped in the insulation during cold winter months.
The paper creates a vapor barrier that helps keep the water vapor in the warm moist heated indoor air from migrating outward into the wall or other structure.
Also on the graph is the permeance of polyethylene.
Not every wall does.
Joe says in the article plastic vapor barriers really are vapor barriers when things get wet.
The purpose of insulation facing the facing on kraft faced insulation is made of kraft paper with an asphalt coating that makes the paper impermeable to water vapor.
A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter.
The best approach for a vented attic in a cold climate is installing a layer of drywall with a good coat of latex paint the paint creates a semi permeable vapor barrier.
Vapor barriers in attics should only be installed on one side of the insulation.
The insulation fiberglass or cellulose is then placed on top of the drywall with no vapor barrier above or below.
The wetter it gets the better it dries.
If you put it on the right side where the humidity is it s not much of a vapor retarder.
Not so asphalt saturated kraft paper.
Never compress or fluff your insulation.