Does Blown In Cellulose Insulation Need A Vapor Barrier

A lot of us with older 100 years homes are getting energy audits with recommendations to blow in cellulose into the empty exterior wall cavities.

Does blown in cellulose insulation need a vapor barrier.

But you do need to perform air sealing work before beginning the insulation job. Not every wall does. I have read that without a vapor barrier. Air sealing an attic.

Cellulose insulation has an average thermal value of r 3 7 so you d need just over five inches to equal an r 19 batt. That s because cellulose is the only insulation that actually manages moisture. This article explains the necessary work. It does an excellent job of limiting air movement and because it is hygroscopic definition.

A bag of cellulose runs about 11 50 and will cover 36 7 square feet at a. Homes and buildings located in a colder northern climates of the continental u s. Moisture moves by two transport mechanism. If you decide to go ahead with the plan to install cellulose on the attic floor you don t need a vapor barrier.

After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one. Thousands of houses. Does his house need a vapor barrier with blown in insulation. Cima does not recommend the use of vapor barriers with cellulose insulation except in circumstances of exceptionally high moisture levels such as an indoor pool facility or very cold climates.

Without a vapor barrier show faster drying and lower overall moisture levels over identical assemblies with vapor barriers installed. Your first job after the studs are in place is to fill those walls with insulation. Air movement and diffusion. In summary we do not recommend the use of vapor barriers with cellulose insulation except in circumstances of exceptionally high moisture levels such as an indoor pool facility and we warrant our cellulose insulation for the life of the building when installed by an approved greenfiber insulation contractor.

Are getting energy audits with recommendations to blow in cellulose into the empty exterior wall cavities. According to fallow we are not sure we agree cellulose insulation requires no vapor barrier in the overwhelming majority of installations. Hygroscopic means a substance tends to absorb moisture from air it manages moisture as well. If you are not sure if you need insulation in your walls follow along with this flow chart.