Does Attic Insulation Need A Vapor Barrier

Since you already have insulation if there was a moisture problem you probably would have noticed signs of it already.

Does attic insulation need 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. Several layers of paint on the ceiling would qualify as a vapor barrier. Whether or not you need a vapor retarder hinges on three main factors your climate your home and the location of the wall you re insulating. 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.

A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter. A plastic vapor barrier is best installed in a vented attic within climates with over 8 000 heating degree days. Not every wall does. If your climate does not meet these conditions a vapor retarder like latex ceiling paint will work well for your house if you are in all other climates except the hot dry and hot humid.

The insulation fiberglass or cellulose is then placed on top of the drywall with no vapor barrier above or below. You do not need a vapor barrier. If you read the brief it points out the major concern with moisture in insulation is air leakage. Adding a second vapor barrier could cause condensation to become trapped in the insulation between the two vapor barriers.

Most forms of attic insulation benefit from the addition of a vapor barrier to protect them from the harmful effects of moisture which can reduce their effectiveness over time.