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  1. #1
    Join Date
    Nov 2011
    Posts
    5

    Question Insulation on Porch Ceiling

    I live in north central Florida and am planning to replace a porch ceiling with 1x6" t+g pine beadboard.
    1)Should the porch ceiling have insulation between the joists and if so, should this be faced or unfaced?
    I'm concerned about the possibility of condensation forming between the faced insulation and the new pine ceiling.
    2) I plan to stain and varnish the pine boards. Is it beneficial to stain both the face and back of the boards to "seal" them against moisture or does this prevent proper "breathing?

  2. #2
    Join Date
    Dec 2010
    Location
    Melrose, Ma
    Posts
    22

    Default Re: Insulation on Porch Ceiling

    Did the same project last year here in Boston. I installed t&g cedar, stained both sides, 2 coats on the front, and 1 coat of spray spar urethane. (don't forget to stain inside the grooves) I drilled, I think, 8 holes in varies locations and blew in the insulation. Never did anything like that before, however it was very easy. But if you are going to use rolled insulation, I would recommend using faced and since you are in FL, have the paper facing the subfloor not the pine.

  3. #3
    Join Date
    Nov 2011
    Posts
    5

    Default Re: Insulation on Porch Ceiling

    The area above the new ceiling is attic space so I'm a little confused about the insulation face.
    I've always heard that the facing should go on the "warm" side but in the case of a porch this seems debatable.
    The attic would be warmer, however, interior areas of the house all required facing to be on the "inside" of the ceiling joists with insulation facing the attic.
    Attic spaces all have an additional layer of R 30 unfaced insulation running perpendicular to the ceiling joists.
    Thanks for the reply.

  4. #4
    Join Date
    Aug 2007
    Location
    Portland, Oregon, formerly of Chicago
    Posts
    1,583

    Default Re: Insulation on Porch Ceiling

    Where the vapor barrier goes kind of depends how the room, or enclosed porch, is used. Is the room air-conditioned and/or heated? In warm , humid areas such as Florida, the vapor barrier is put on the exterior side if the room is air-conditioned. Moist, hot air will try to migrate to the cooler, drier interior space. Therefore, the vapor barrier hinders it entering the conditioned space. If however, the room is not air-conditioned, the point is mute.

    In areas of the country where the seasons are temperate, absolute vapor barriers are often omitted. It is better to let the moisture pass on through rather than have it trapped in the wall cavity.

    There have been nightmare scenarios in hot humid areas where plastic was used as a vapor barrier behind the drywall. The humid air would condense on the cool drywall inside the wall cavity and literally have flowing water running down and soaking carpets in the homes. It literally drove a large, established builder into bankruptcy.

    One thing for sure, you want that overhead area ventilated.

    Were it mine, I would seal the backside of the ceiling boards. It not only protects against moisture, but helps make the boards more stable as seasonal conditions vary.

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