Fiberglass Insulation Vapor Barrier Installation

A smart vapor retarder is able to adapt its permeability to allow the wall to dry should moisture get trapped in the wall cavity.

Fiberglass insulation vapor barrier installation.

Vapor barriers are sheets of plastic or other material placed on one side of insulation sheets. Cut short pieces of paper faced fiberglass insulation called blockers and set them between the floor joists and tight against the outside wall. 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. This barrier is meant to keep moisture from getting to the insulation in the walls and ceilings and it is required by building codes when insulating most houses.

The facing on kraft faced insulation is made of kraft paper with an asphalt coating that makes the paper impermeable to water vapor. First install the fiberglass insulation between the studs and then apply the vapor barrier over the installed fiberglass insulation. Not be trapped inside. For many building science questions the answer is it depends for this one the answer is clear.

These batts can come faced or unfaced. In any case the vapor barrier must point to the warm side. Faced means with built in kraft paper on one side that is used to form a vapor barrier. Wall insulation can come in different types.

Vapor barriers in attics should only be installed on one side of the insulation. To the inside of the home or the outside of the home. 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. Never compress or fluff your insulation.

Cover the unfaced fiberglass wall insulation with a 3 mil polyethylene vapor barrier. The paper should face the inside of the home. For this reason faced insulation is typically installed on the. It can be blown in polystyrene or fiberglass batts.

Installing vapor barrier over your head. 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. 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. 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.

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. If you install fiberglass batt insulation with a kraft paper vapor retarder in a home which way do you face the vapor retarder.