Attic Insulation Vapor Retarder

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Attic insulation vapor retarder.

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. First the kraft paper is a vapor retarder meant to reduce the potential for moisture problems caused by diffusion. Attic vapor barrier detail for cold climates 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. Adding a second vapor barrier could cause condensation to become trapped in the insulation between the two vapor barriers.

A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter. To know if you need a vapor retarder ask yourself a few basic questions. Plastic vapor barriers should only be installed in vented attics in climates with more than 8 000 heating degree days. Whether or not you need a vapor retarder hinges on three main factors your climate your home and the location of the wall you re insulating.

A vapor barrier or vapor diffusion retarder is a material that reduces the rate at which water vapor can move through a material. Air movement and diffusion. If this is accomplished and a similar air infiltration retarder is installed in sidewalls mechanical ventilation such as a heat recovery ventilator should be installed to prevent trapping air pollutants and moisture within the house. Vapor barriers are sheets of plastic or other material placed on one side of insulation sheets.

That s because cellulose is the only insulation that actually manages moisture. The insulation fiberglass or cellulose is then placed on top of the drywall with no vapor barrier above or below. The older term vapor barrier is still used even though vapor diffusion retarder is more accurate. Sounds like a good idea but the vast majority of moisture problems are caused by air leakage not diffusion even in places like maine.

Do the air sealing. Stop worrying so much about vapor retarders. Moisture moves by two transport mechanism. This acts as a barrier to keep heated moist air from rising up into the attic during cold weather.

If installed in an attic a continuous vapor retarder is usually used to reduce air infiltration. 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. Attic insulation should always be installed with the paper backing facing toward the living space the ceiling in this case.