Definition of vapor barrier in US English:

vapor barrier


  • A thin layer of impermeable material, typically polyethylene sheeting, included in building construction to prevent moisture from damaging the fabric of the building.

    • ‘It is the purpose of the vapor barrier to prevent that movement or penetration of moisture from one area to another.’
    • ‘This vapor barrier will prevent evaporation of ground moisture, thereby reducing the likelihood of condensation.’
    • ‘The masonry walls are lined with heavy concrete blocks and separated from the rest of the building by a vapour barrier, so minimizing changes in temperature and humidity.’
    • ‘Installing subfloor insulation with the vapor barrier on the downward side can cause moisture condensation on the framing and subfloor.’
    • ‘The necessity of constructing a vapor barrier for humidity control around the building - all museums require them - complicates things further.’