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.
Attic insulation moisture barrier.
Vapor barriers in attics should only be installed on one side of the insulation.
After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one.
This really helps prevent trapped moisture between a traditional vapor barrier and the drywall.
A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter.
The heat being lost from the house below warmed up the attic so that moisture was lost through the vents as vapor.
They don t however reduce heat conduction like thermal insulation materials.
In any case the vapor barrier must point to the warm side.
Not every wall does.
Never compress or fluff your insulation.
This acts as a barrier to keep heated moist air from rising up into the attic during cold weather.
Vapor barriers are sheets of plastic or other material placed on one side of insulation sheets.
The insulation fiberglass or cellulose is then placed on top of the drywall with no vapor barrier above or below.
The latex paint allows the ceiling to breath a bit but still help prevent significant movement of air and water vapor.
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.
Attic insulation should always be installed with the paper backing facing toward the living space the ceiling in this case.
Radiant barriers are installed in homes usually in attics primarily to reduce summer heat gain and reduce cooling costs.
Adding a second vapor barrier could cause condensation to become trapped in the insulation between the two vapor barriers.
The barriers consist of a highly reflective material that reflects radiant heat rather than absorbing it.
Now with attic insulation heat is no longer lost from the living space such that moisture may remain trapped in the attic vapor barriers were therefore necessary to reduce moisture flow into the attic.