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  • vapor barrier, vapor retarder



    • Related References
  • Baechler, M. C. and Love, P. M., (2005), Building America Best Practices Series: Volume 3 ¨C Builders and Buyers Handbook for Improving New Home Efficiency, Comfort, and Durability in the Cold and Very Cold Climates
  • Lstiburek, J., (2004), Builder's guide: cold climates



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    		Essay:

    Vapor Management--Building America Best Practices Series: Volume 3

    Water has many guises and water in its liquid state is not the only problem. Water can also cause problems as vapor. The problem is especially bad when vapor gets trapped within an assembly, such as a wall; turns to its liquid form (condenses); and wets structural assemblies. Condensation can also form in and on ductwork, especially when air conditioning cools duct surfaces that come in contact with humid air, such as in an attic or crawlspace. The recommendations below are intended to help control both liquid water and vapor.

    Best Practice: In cold climates, air barriers and vapor retarders are installed on the interior of the building assemblies. And building assemblies are designed to dry to the exterior by installing permeable sheathings and building paper or housewraps toward the exterior (Lstiburek 2004). Unless specifically required by local building code, a polyethylene vapor retarder (between the framing and the drywall) is not recommended because it limits a wallĄ¯s ability to dry to the inside. In a wood frame wall with carefully installed batt insulation, the kraft facing on the batt would provide the necessary protection against vapor diffusion from interior sources for this climate. In the case of other exterior wall assemblies, drywall painted with latex paint suffices (Broniek, 2003).

    Source: Baechler and Love, 2005, Building America Best Practices Series: Volume 3 ¨C Builders and Buyers Handbook for Improving New Home Efficiency, Comfort, and Durability in the Cold and Very Cold Climates ,, page 41.

    * Lstiburek, Joseph. 2004. Builders Guide to Cold Climates. Lstiburek, 2004, BuilderĄ¯s guide: cold climates

    * Broniek, John. 2003. Builder System Performance Packages Technical Report. Prepared by IBACOS for the Building America Program. www.buildingamerica.gov




    More info of this article can be found on the web at: This link has not been checked.http://www1.eere.energy.gov/buildings/building_america/cold_case_studies.html


    CRDBER, at CBS, BCEE, ENCS, Concordia,