Not be trapped inside.
Attic insulation vapor barrier cellulose.
Should you install a vapor barrier over preexisting attic insulation.
Vapor barriers in attics should only be installed on one side of the insulation.
The hygroscopic nature of cellulose insulation allows it to manage and wick moisture from areas of greater to lesser concentrations thus preventing damaging amounts of moisture from accumulating.
The us department of energy classifies cellulose insulation as a class iii vapor retarder.
The paper facing contains a layer of impermeable asphalt that prevents water vapor from passing through it.
It s actually a smart vapor retarder since its permeability decreases as moisture content increases.
If you decide to go ahead with the plan to install cellulose on the attic floor you don t need a vapor barrier.
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.
The insulation fiberglass or cellulose is then placed on top of the drywall with no vapor barrier above or below.
Air sealing an attic.
No the best option is to install un faced or loose fill fiberglass or cellulose on top of your drywall.
A vapor barrier is not only unnecessary but also can be potentially harmful especially during the summer months in air conditioned buildings when warm moist air passes through wall assemblies and condenses on the outside of the cool poly vapor barrier.
With our vapor barrier installation services there will be no issue of the crawl space of your home becoming a residence for pests bats and rodents.
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.
They help keep moisture from migrating into walls by diffusion but still allow for drying so it doesn t get trapped.
The best way to answer this question in addition to considering the factors above would be to talk to a professional.
Insulation labs is a name to reckon with for efficient vapor barrier installation services.