Do I Need A Vapor Barrier In Attic

However all attics vented or unvented and in all climates should have an air barrier such as an airtight drywall ceiling.

Do i need a vapor barrier in attic.

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. 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. If you are not sure if you need insulation in your walls follow along with this flow chart.

If you read the brief it points out the major concern with moisture in insulation is air leakage. In hot dry climates your attic can be vented though like in hot humid climates you should not install any vapor retarder or barrier. Air sealing an attic. The following are a few simple steps to help you undertake the task properly so your vapor barrier retains heat without damaging the insulation.

No you don t need a vapor barrier. By the time you paint the drywall though you ve brought it into the class iii vapor retarder range between 1 and 10 perms and even less water vapor will diffuse through. Seal the air leakage pathways. Do i need a vapor barrier.

For example the recommended vapor barrier in a home or office in a humid southern climate built with brick varies. Hi beth 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. The paper facing contains a layer of impermeable asphalt that prevents water vapor from passing through it. Several layers of paint on the ceiling would qualify as a vapor barrier.

No you don t need a vapor retarder class i or otherwise. After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one. 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. Not every wall does.

Since you already have insulation if there was a moisture problem you probably would have noticed signs of it already. Your first job after the studs are in place is to fill those walls with insulation. When it comes to the stairway leading into your attic you should heed the advice in this article. A vapor barrier in an attic assembly in a severely cold climate with the absence of an air barrier will likely be ineffective.

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.