Attic Insulation Ceiling Vapor Barrier

Plastic vapor barriers should only be installed in vented attics in climates with more than 8 000 heating degree days.

Attic insulation ceiling vapor barrier. Attic insulation should always be installed with the paper backing facing toward the living space the ceiling in this case. A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter. Blowing insulation into walls is best left to the pros because it involves drilling into stud spaces that may contain electrical. Vapor barriers in attics should only be installed on one side of the insulation.

Then cover the foam with drywall as required for fire safety. Hence a need to reduce moisture flow into the attic and add a vapor barrier. After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one. You can forego the plastic and use a vapor retarder kraft faced insulation or latex ceiling paint in all other climates except hot humid or hot dry climates.

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. Foam blocks airflow needs no vapor barrier and has a higher r value per inch than loose fill or batts so you ll get more protection with less depth. Not be trapped inside. Never compress or fluff your insulation.

Attic moisture was then picked up and vented to exterior. Before the introduction of attic insulation attics in cold climates were poorly insulated and plastic ceiling vapor barriers were omitted. However all attics vented or unvented and in all climates should have an air barrier such as an airtight drywall ceiling. 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 approach worked great until large quantities of attic insulation were added. Handy homeowners can install blown in insulation in the attic. With spray foam unlike with loose fill or batts you must cover the soffit vents they aren t needed to keep the roof cool. Adding a second vapor barrier could cause condensation to become trapped in the insulation between the two vapor barriers.

With added insulation attic and ventilating outside air both stayed cold unable to effectively remove attic moisture.