Do You Need Vapor Barrier Blown Insulation Attic

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

Do you need vapor barrier blown insulation 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. Plastic vapor barriers should only be installed in vented attics in climates with more than 8 000 heating degree days. You will see on which side is the vapor barrier. Due to this inevitable fact it s actually better to omit a vapor barrier between the insulation and drywall of the ceiling below the attic.

Thousands of houses have had insulation blown in without incident mostly because old houses are so leaky that there is little or no chance for water vapor to build up to cause the insulation to. Not every wall does. Your first job after the studs are in place is to fill those walls with insulation. After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one.

To assure proper protection of the vapor barrier you will need to cover the entire area of the 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. Lucy no you don t need a vapor barrier. Should you install a vapor barrier over preexisting attic insulation.

No the best option is to install un faced or loose fill fiberglass or cellulose on top of your drywall. The paper facing contains a layer of impermeable asphalt that prevents water vapor from passing through it. Since you already have insulation if there was a moisture problem you probably would have noticed signs of it already. You do not need a vapor barrier.

The best approach for a vented attic in a cold climate is installing a layer of drywall with a good coat of latex paint the paint creates a semi permeable vapor barrier. Air sealing an attic. The best way to answer this question in addition to considering the factors above would be to talk to a professional. Most of the blanket insulation types have vapor barriers incorporated and can be very effective if installed properly.

The basics of air sealing are covered in this article. If you read the brief it points out the major concern with moisture in insulation is air leakage. 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. Several layers of paint on the ceiling would qualify as a vapor barrier.