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Vapour Barriers

marcus1977 | Posted in General Questions on

Hello is it more likely that more water vapour is carried through a wall assembly by air leakage than vapour Diffusion? Can the perm rating of a paint change over years if there is a roof leak causing moisture issues with in a home?
zone 5 in the country.
Thank You for your time.

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Replies

  1. Expert Member
    MALCOLM TAYLOR | | #1

    Marcus1977,

    Yes, exponentially more moisture makes its way into most building assemblies through air leakage than does through diffusion.

    I'm sorry I don't know how roof leakage affects the permeability of paints.

    1. marcus1977 | | #3

      Thank you so much for your input

  2. Expert Member
    BILL WICHERS | | #2

    I'm not aware of any information as to paint chaning it's properties over time. I would expect the vapor control properties of paint to remain relatively stable over time though, unless you have peeling, cracking, or other issues showing failure of the paint.

    I don't see how a roof leak applies here. If a roof leak is letting moisture into the home in the form of bulk water (drip drip, trickle, etc.), then the air sealing and moisture control of the building isn't really the problem, the leaky roof is.

    Bill

  3. marcus1977 | | #4

    Thank You so much for your reply

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