Does Attic Insulation Need A Vapor Barrier

Several layers of paint on the ceiling would qualify as a vapor barrier.

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. This acts as a barrier to keep heated moist air from rising up into the attic during cold weather. A plastic vapor barrier is best installed in a vented attic within climates with over 8 000 heating degree days. 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. Since you already have insulation if there was a moisture problem you probably would have noticed signs of it already. A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter. Adding a second vapor barrier could cause condensation to become trapped in the insulation between the two vapor barriers.

Attic insulation should always be installed with the paper backing facing toward the living space the ceiling in this case. 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. 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. Not every wall does.

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.