Attic Vapor Barrier

Attic vapor barrier detail for cold climates.

Attic vapor barrier.

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. 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 the following are a few simple steps to help you undertake the task properly so your vapor barrier retains heat without damaging the insulation. In existing spaces oil based paints or vapor barrier latex paints offer an effective moisture barrier.

Some regions don t require a vapor barrier. The inner surface in colder climates and the outer surface in hot humid climates. Because it s nearly impossible to seal penetrations in the ceiling the reality is water vapor will get into the attic. The paper facing contains a layer of impermeable asphalt that prevents water vapor from passing through it.

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.