Not every wall does.
Do i need attic vapor barrier in sc.
Such a location works both as a vapor barrier as well as an air barrier and eliminates the need for an external air barrier not a easy application on a multi storried building as well as any special electrical pans and their sealing.
Do not add a vapor barrier on top of the insulation in your attic since the paper facing on the existing insulation is the vapor barrier.
For example the recommended vapor barrier in a home or office in a humid southern climate built with brick varies.
The paper facing contains a layer of impermeable asphalt that prevents water vapor from passing through it.
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.
Whether or not you need a vapor retarder hinges on three main factors.
A plastic vapor barrier is best installed in a vented attic within climates with over 8 000 heating degree days.
There s one other important qualification.
Once thought to be essential throughout a home or office vapor barriers are now strongly recommended only for certain conditions and methods for creating a vapor barrier must be tailored to fit the climate region and type of wall construction.
Because it s nearly impossible to seal penetrations in the ceiling the reality is water vapor will get into the attic.
When a vapor barrier is on the side of a wall where the dry air is i e outside in winter or inside in summer moisture problems can occur.
Even though we apply vapor barriers to exterior insulated walls in cold climates it s no longer recommended for ceilings floor of the attic.
Vapor moves in two ways by diffusion through materials and by air leakage through gaps and holes in building assemblies.
The class i vapor barriers such as 6 mil thick polyethylene sheets stop moisture migration from the bare earth into the house.
Many people believe that it is a good idea to cover the earth with a vapor barrier even if you do meet the 1 square foot to 500 square feet requirement.
A vapor barrier s job is to keep water vapor in humid air from diffusing through one side of a wall and finding a cool surface inside the wall.
A vapor barrier reduces the movement of water vapor by.
Hence the need to reduce moisture flow into the attic and the need for a vapor barrier.
I install my vapor barrier in the middle of the wall system between the two walls.
Attic vapor barrier detail for cold climates.
What climate do you live in.
