Do You Need Vapor Barrier Blown Insulation 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.

Do you need vapor barrier blown insulation attic.

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. 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. This means also the access hatch.

Not every wall does. Plastic vapor barriers should only be installed in vented attics in climates with more than 8 000 heating degree days. To assure proper protection of the vapor barrier you will need to cover the entire area of the attic. You will see on which side is the vapor barrier.

The paper facing contains a layer of impermeable asphalt that prevents water vapor from passing through it. 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. If you read the brief it points out the major concern with moisture in insulation is air leakage. 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.

Most of the blanket insulation types have vapor barriers incorporated and can be very effective if installed properly. Several layers of paint on the ceiling would qualify as a vapor barrier. Lucy no you don t need a vapor barrier. What you need is an air barrier that is at every step of the way you have to pay attention to airtightness.

The basics of air sealing are covered in this article. 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. 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.

If you are not sure if you need insulation in your walls follow along with this flow chart. You do not need a vapor barrier. 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. 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.