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  1. #1
    Join Date
    Dec 2008
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    Erwin, TN
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    330

    Default Insulating between the attic rafters ??

    I have never seen this before in 13 yrs of inspecting homes. This remodeled 1970 home had R-19 between the ceiling joists and R-19 between the rafters with the paper exposed, what were they thinking (i know that total R valve equals R-38) ?? Has anyone seen this before and am I missing something ?? (our R-value in my zone in Tennessee is R-38)

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  2. #2
    Join Date
    Mar 2007
    Location
    Fletcher, NC
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    28,032

    Default Re: Insulating between the attic rafters ??

    Vented attic?

    If so, the insulation at the roof sheathing doesn't do anything (other than create the issue of the exposed facing, which is a fire hazard).

    Other likely issues too.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  3. #3
    Join Date
    Dec 2008
    Location
    Erwin, TN
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    330

    Default Re: Insulating between the attic rafters ??

    Quote Originally Posted by Jerry Peck View Post
    Vented attic?

    If so, the insulation at the roof sheathing doesn't do anything (other than create the issue of the exposed facing, which is a fire hazard).

    Other likely issues too.
    Yes, Ridge, Gable and soffit vents


  4. #4
    Join Date
    Feb 2008
    Location
    Chicago IL
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    2,048

    Default Re: Insulating between the attic rafters ??

    I think it comes under the heading of 'unclear on the concept'.

    www.aic-chicago.com
    773/844-4AIC
    "The Code is not a ceiling to reach but a floor to work up from"

  5. #5
    Join Date
    Feb 2009
    Location
    Southern Vancouver Island
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    4,607

    Default Re: Insulating between the attic rafters ??

    It might have been the start of making that attic warmer for storage, such as a drywalled storage area that will trap heat from below. It would still need ventilation, but they could be adjustable vents.

    John Kogel, RHI, BC HI Lic #47455
    www.allsafehome.ca

  6. #6
    Join Date
    Mar 2007
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    Fletcher, NC
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    Default Re: Insulating between the attic rafters ??

    Quote Originally Posted by John Kogel View Post
    It might have been the start of making that attic warmer for storage, such as a drywalled storage area that will trap heat from below. It would still need ventilation, but they could be adjustable vents.
    If they created a 'storage room', insulated and drywalled, it would be, at the very least could be, considered 'not attic' space and would not need to be ventilated.

    Depending on various things, that 'storage room' could be "unconditioned" space, or even "conditioned" space.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  7. #7
    Join Date
    Aug 2011
    Location
    Bennett (Denver metro), Colorado
    Posts
    1,461

    Default Re: Insulating between the attic rafters ??

    I've seen this done a fair number of times. The 'ol more is better concept that ain't necessarily true. I report any (if any) problems arising from arrangement and note potential issues, such as inadequate ventilation might cause composition shingles to prematurely age, and move on.

    If you choose not to decide, you still have made a choice.

  8. #8
    Join Date
    Apr 2013
    Location
    High Springs, Florida
    Posts
    174

    Default Re: Insulating between the attic rafters ??

    What makes it any different than if they had spray foam up there?
    Just a question.


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  9. #9
    Join Date
    Feb 2009
    Location
    Southern Vancouver Island
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    4,607

    Default Re: Insulating between the attic rafters ??

    Quote Originally Posted by Roy Lewis View Post
    What makes it any different than if they had spray foam up there?
    Just a question.
    The answer would depend on the location. An insulated roof deck would probably reduce attic heat in the summer, a good thing.

    There are new building techniques coming into effect all the time. Spray foam is fantastic, but only if no moisture is trapped behind it.
    In a northern climate, the insulation needs to be on the ceiling of the living space. My new addition had to have R40, 12" of fiberglass, on the ceiling to keep the heat where we want it. The underside of the roof deck is clear to allow ventilation of the wood and I used real plywood.

    John Kogel, RHI, BC HI Lic #47455
    www.allsafehome.ca

  10. #10
    Join Date
    Mar 2007
    Location
    Fletcher, NC
    Posts
    28,032

    Default Re: Insulating between the attic rafters ??

    Quote Originally Posted by Roy Lewis View Post
    What makes it any different than if they had spray foam up there?
    Just a question.
    The first difference is that when they spray foam up on the underside of the roof decking is because the attic is being changed from a ventilated attic to a sealed attic.

    That attic is still a ventilated attic, thus "any" insulation up on the underside of the roof decking is, well, useless.

    Second, there are other considerations between foam and fiberglass insulation in that use (sealed attics), but in this case, those points a moot as the attic is a vented attic.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  11. #11
    Join Date
    Jun 2008
    Location
    Stacy, MN
    Posts
    148

    Default Re: Insulating between the attic rafters ??

    If the brick is a masonry fireplace it doesn't look like they have 2 inches of clearance to combustibles.


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