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  1. #1
    Join Date
    Mar 2015
    Posts
    1

    Default To vent or not to vent: I'm completely baffled with attic insulation

    My attic is 1300sq" of beautiful, wide open space. It is currently NOT insulated, and this needs to be remedied. Eventually, I would like to use the attic space as a livable, occupied space, so I want to do the insulation right the first time. I've talked to many vendors, and each one has given me a different story on how to approach this job.

    • Fiberglass with baffles
    • Fiberglass WITHOUT baffles
    • Soffit and ridge vents
    • NO venting necessary!
    • Spray foam, fiberglass, "green" materials, OH MY!


    Ultimately, I need to hear from people who know what they are talking about to get some solid advice. My biggest question: Do I need to cut ridge and soffit vents? Or does this completely depend on which insulation material I use? Thanks, everyone!

  2. #2
    Join Date
    Dec 2007
    Location
    Tennessee
    Posts
    1,791

    Default Re: To vent or not to vent: I'm completely baffled with attic insulation

    Before you make this living space, you need to find the point on the rafters that is 8' above the joists, on each side of the attic, then measure the distance between these points. Then also find the points where the rafters are 5' above the joists, that is from the top of the joist to the bottom of the rafter. The distance between the 5' marks will be the maximum width of the room, the distance between the 8' points will be the width of the flat ceiling. Between the 8' and 5' will be a slated ceiling. Now decide if the room will be big enough.

    The walls at the 5' marks will be kneewall. Outside of that is attic space where you insulate the kneewall and between the joists. You insulate the slanted ceiling, but there must be enough room above the insulation for air to flow. If your rafters are 2x8 or smaller, you will need some baffles. If the rafters are 2x10 or 2x12, and you use insulation that is less than 8.5" or 10.5", you will not need baffles. Then you insulate the joists of the ceiling in your new room.

    If you have 2x6 rafters, you can fir out the rafters to increase the depth of the cavity for more insulation or you could use R-13 batts between the rafters with the gap between the insulation and the roof, then use 1" closed cell foam sheets (4x8') between the rafters and the sheetrock of the slanted ceiling. I would suggest at least 1/2" foam between the rafters and the sheet rock of the slanted ceiling in any case, but a full inch if you only have 2x6 rafters.

  3. #3
    Join Date
    Mar 2015
    Posts
    9

    Default Re: To vent or not to vent: I'm completely baffled with attic insulation

    Quote Originally Posted by SarahAnn View Post
    My attic is 1300sq" of beautiful, wide open space. It is currently NOT insulated, and this needs to be remedied. Eventually, I would like to use the attic space as a livable, occupied space, so I want to do the insulation right the first time. I've talked to many vendors, and each one has given me a different story on how to approach this job.

    • Fiberglass with baffles
    • Fiberglass WITHOUT baffles
    • Soffit and ridge vents
    • NO venting necessary!
    • Spray foam, fiberglass, "green" materials, OH MY!


    Ultimately, I need to hear from people who know what they are talking about to get some solid advice. My biggest question: Do I need to cut ridge and soffit vents? Or does this completely depend on which insulation material I use? Thanks, everyone!

    This is exactly what i am going thru. I decided after much reading and questioning to do baffles, foam and preserve my roof venting.

    Keith is correct 1st decide if its enough room to warrant because foam is pricey and no so easy to work with.

    Good luck !!

  4. #4
    Join Date
    Mar 2015
    Posts
    9

    Default Re: To vent or not to vent: I'm completely baffled with attic insulation

    Quote Originally Posted by keith3267 View Post
    Before you make this living space, you need to find the point on the rafters that is 8' above the joists, on each side of the attic, then measure the distance between these points. Then also find the points where the rafters are 5' above the joists, that is from the top of the joist to the bottom of the rafter. The distance between the 5' marks will be the maximum width of the room, the distance between the 8' points will be the width of the flat ceiling. Between the 8' and 5' will be a slated ceiling. Now decide if the room will be big enough.

    The walls at the 5' marks will be kneewall. Outside of that is attic space where you insulate the kneewall and between the joists. You insulate the slanted ceiling, but there must be enough room above the insulation for air to flow. If your rafters are 2x8 or smaller, you will need some baffles. If the rafters are 2x10 or 2x12, and you use insulation that is less than 8.5" or 10.5", you will not need baffles. Then you insulate the joists of the ceiling in your new room.

    If you have 2x6 rafters, you can fir out the rafters to increase the depth of the cavity for more insulation or you could use R-13 batts between the rafters with the gap between the insulation and the roof, then use 1" closed cell foam sheets (4x8') between the rafters and the sheetrock of the slanted ceiling. I would suggest at least 1/2" foam between the rafters and the sheet rock of the slanted ceiling in any case, but a full inch if you only have 2x6 rafters.

    Great advice!!!!

    My solution was i made the kneewall part into closets and cut out 4 rafters, and tripled the opening up with lam's to make 1 big T shaped room surrounded by 4 closets. I plan to leave my ceiling slanted, I like how it looks. Storage and living space in a warm attic, when its all done Ill add a ductless split for comfort. I cant wait till all this is done its so much work for 1 person.

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