Do You Need Vapor Barrier Blown Insulation Attic

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.

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. Most of the blanket insulation types have vapor barriers incorporated and can be very effective if installed properly. You do not need a vapor barrier.

If you read the brief it points out the major concern with moisture in insulation is air leakage. What you need is an air barrier that is at every step of the way you have to pay attention to airtightness. Several layers of paint on the ceiling would qualify as a vapor barrier. 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 basics of air sealing are covered in this article. You will see on which side is the vapor barrier. If you are not sure if you need insulation in your walls follow along with this flow chart. Should you install a vapor barrier over preexisting attic insulation.

The following are a few simple steps to help you undertake the task properly so your vapor barrier retains heat without damaging the insulation. Air sealing an attic. 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. The paper facing contains a layer of impermeable asphalt that prevents water vapor from passing through it.

Not every wall does. The best way to answer this question in addition to considering the factors above would be to talk to a professional. No the best option is to install un faced or loose fill fiberglass or cellulose on top of your drywall. You can forego the plastic and use a vapor retarder kraft faced insulation or latex ceiling paint in all other climates except hot humid or hot dry climates.

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. To assure proper protection of the vapor barrier you will need to cover the entire area of the attic. Since you already have insulation if there was a moisture problem you probably would have noticed signs of it already. After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one.