A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter.
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.
In hot dry climates your attic can be vented though like in hot humid climates you should not install any vapor retarder or barrier.
Not every wall does.
Plastic vapor barriers should only be installed in vented attics in climates with more than 8 000 heating degree days.
Because it s nearly impossible to seal penetrations in the ceiling the reality is water vapor will get into the attic.
After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one.
You have loose fill insulation in the attic which doesn t have a vapor barrier.
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 paper facing contains a layer of impermeable asphalt that prevents water vapor from passing through it.