Do I Need A Vapor Barrier In Attic

Attic vapor barrier detail for cold climates even though we apply vapor barriers to exterior insulated walls in cold climates it s no longer recommended for ceilings floor of the attic.

Do i need a vapor barrier in attic. Not every wall does. A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter. However all attics vented or unvented and in all climates should have an air barrier such as an airtight drywall ceiling. Because it s nearly impossible to seal penetrations in the ceiling the reality is water vapor will get into the attic.

Plastic vapor barriers should only be installed in vented attics in climates with more than 8 000 heating degree days. The theory is that part of the moisture vapor in the house is actually blocked by the drywall and paint on the. In hot dry climates your attic can be vented though like in hot humid climates you should not install any vapor retarder or barrier. You have loose fill insulation in the attic which doesn t have 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.