Attic Insulation Vapor Barrier Cellulose

Do not add a vapor barrier on top of the insulation in your attic since the paper facing on the existing insulation is the vapor barrier.

Attic insulation vapor barrier cellulose.

If you decide to go ahead with the plan to install cellulose on the attic floor you don t need a vapor barrier. The us department of energy classifies cellulose insulation as a class iii vapor retarder. 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 paper facing contains a layer of impermeable asphalt that prevents water vapor from passing through it.

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. This article explains the necessary work. 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. Air sealing an attic.

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. It s actually a smart vapor retarder since its permeability decreases as moisture content increases. They help keep moisture from migrating into walls by diffusion but still allow for drying so it doesn t get trapped.

But you do need to perform air sealing work before beginning the insulation job. Not be trapped inside. No the best option is to install un faced or loose fill fiberglass or cellulose on top of your drywall. 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.

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.