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  1. #1
    Join Date
    Mar 2009
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    2

    Default Ceiling Joist Insulation

    Hi,

    I have a 8" wooden ceiling joists. On these there is a plaster ceiling. The joists have 4" batt insulation. However there is a 1.5" to 2" air space between the insulation and the plaster ceiling. The ceiling also lacks a vapor barrier. Is it advisable to fill this air space with an additional 4" batt insulation, thus doubling my R value, or should i leave as is?

  2. #2
    Join Date
    Mar 2009
    Posts
    1,387

    Default Re: Ceiling Joist Insulation

    Hi i am confused is there a 2" gap above the insluation or below it? Is the home one or more stories ? If one story then is this area a flat roof? The flat roof would need the air space to allow air in this attic space to allow movement of moisture out of the 2 " attic space...

  3. #3
    Join Date
    Mar 2009
    Posts
    2

    Default Re: Ceiling Joist Insulation

    It's a single storey home, with a traditional pitched roof. The 2" air gap is between the plaster ceiling and the underside of the insulation.

  4. #4
    Join Date
    Mar 2009
    Posts
    1,387

    Default Re: Ceiling Joist Insulation

    Howdy, what is holding the insulation up? Were bats laid perpendicular to the joists instead of in between the joists?
    The norm is to have the insulation on the ceiling not to have an air gap in between.

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