Vapor barriers are sheets of plastic or other material placed on one side of insulation sheets.
Vapor barrier in attic ceiling.
Whether using loose fill or batts put the vapor barrier closest to the warm side of your installation where hot moist air would get in facing the house s interior in cold climates beneath floor insulation and the attic s interior in hot climates on top of floor insulation.
This acts as a barrier to keep heated moist air from rising up into the attic during cold weather.
In any case the vapor barrier must point to the warm side.
If you live in a cold climate place the vapor barrier between the interior of your home and the insulation.
A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter.
Even though we apply vapor barriers to exterior insulated walls in cold climates it s no longer recommended for ceilings floor of the attic.
On the other hand an air barrier a properly detailed air tight drywall ceiling for example in the absence of a vapor barrier can be effective since it stops the flow of vapor laden air.
A vapor barrier in an attic assembly in a severely cold climate with the absence of an air barrier will likely be ineffective.
Basement ceiling vapor barrier.
Attic vapor barrier detail for cold climates.
Almost 6 years by bv006343.
Some regions don t require a vapor barrier.
Attic insulation should always be installed with the paper backing facing toward the living space the ceiling in this case.
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.
This barrier is meant to keep moisture from getting to the insulation in the walls and ceilings and it is required by building codes when insulating most houses.
Whether your vapor barrier is a facing or a film it must be placed on the warm in winter side of the wall.
Not every wall does.