Fiberglass Insulation Vapor Barrier Installation

If the insulation is installed with the paper vapor barrier facing away from the heated part of the home moisture from humid inside air can condense and become trapped in the insulation during cold winter months.

Fiberglass insulation vapor barrier installation.

The purpose of insulation facing. First install the fiberglass insulation between the studs and then apply the vapor barrier over the installed fiberglass insulation. For many building science questions the answer is it depends for this one the answer is clear. Vapor barriers in attics should only be installed on one side of the insulation.

These batts can come faced or unfaced. Installing vapor barrier over your head. The facing on kraft faced insulation is made of kraft paper with an asphalt coating that makes the paper impermeable to water vapor. Vapor barriers are sheets of plastic or other material placed on one side of insulation sheets.

Wall insulation can come in different types. In addition to fiberglass insulation and vapor barriers the most successful moisture management strategies include a water resistive barrier an interior air barrier and an exterior wind barrier to reduce the potential for seasonal surface condensation and rainwater penetration. Faced means with built in kraft paper on one side that is used to form a vapor barrier. Fiberglass batts are the most common.

When installing your vapor barrier it is important not to compress your fiberglass insulation because they need to remain fluffy in order to keep its r value. Since some leakage of moisture into the insulation in inevitable murphy s law you want it to be able to freely escape from the insulation into the attic. The paper should face the inside of the home. The paper creates a vapor barrier that helps keep the water vapor in the warm moist heated indoor air from migrating outward into the wall or other structure.

Cut short pieces of paper faced fiberglass insulation called blockers and set them between the floor joists and tight against the outside wall. It can be blown in polystyrene or fiberglass batts. In any case the vapor barrier must point to the warm side. Cover the unfaced fiberglass wall insulation with a 3 mil polyethylene vapor barrier.

If you install fiberglass batt insulation with a kraft paper vapor retarder in a home which way do you face the vapor retarder. To the inside of the home or the outside of the home. A smart vapor retarder is able to adapt its permeability to allow the wall to dry should moisture get trapped in the wall cavity. Be sure the paper surface faces out into the room.

Consult an insulation professional in your area if you are unsure where or how to install a vapor retarder or consider a vapor retarder that provides some degree of additional flexibility like a smart vapor retarder. Not be trapped inside.