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Thread: Insulation Help

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  1. #1
    Join Date
    Mar 2010
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    1

    Default Insulation Help

    I have a house which was built in mid 70's. The insulation within the attic is horrible. In some areas it looks like they used insulation which might have been left over from wall insulation. I only say this because I found some pieces as small as a foot long. The attic studs are 2x6's. The insulation within them is about 3" thick. I was doing some research and I believe it may be R19. Unable to really tell as the fiberglass paper itself does not have R rating stamped on it. The fiberglass is a whitish yellow color. I live in Zone 5 and the recommended R value is R49-60. I would like to get my R value up to at least a R30 if possible. I was looking to probably use blow-in insulation (cellulose or fiberglass) and do it myself. The main problem I have is that part of the attic has plywood which we use for storage. I need to keep this storage space if at all possible. Is there a way to get to a good R value in my attic and keep the storage space as well? Thanks in advance.

  2. #2
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: Insulation Help

    Quote Originally Posted by akcrx View Post
    The attic studs are 2x6's.
    Are these the ceiling joists you are referring to?

    The insulation within them is about 3" thick. I was doing some research and I believe it may be R19.
    Not likely --- *maybe* R10 at best

    I live in Zone 5 and the recommended R value is R49-60. I would like to get my R value up to at least a R30 if possible. I was looking to probably use blow-in insulation (cellulose or fiberglass) and do it myself.
    In order to achieve your target R value you will need around 10 inches of blown insulation. If you go the blown in route a recommendation is to pull up the batts then blow in whichever ( personally I prefer cellulose over fiber glass ) and lay the batts over the blown insulation.


    The main problem I have is that part of the attic has plywood which we use for storage. I need to keep this storage space if at all possible. Is there a way to get to a good R value in my attic and keep the storage space as well? Thanks in advance.
    If you are blowing 10 inches of insulation this would obviously end up above the plywood floor used for storage which means you would have less under the floor unless the height of the floor was raised.
    Closed cell spray foam would be the only way to achieve the closet to your target R value under the plywood -- but -- it's very expensive and not a DIY project.

    Side note ----I'd be concerned about only having 2x6 joists and having the weight of items being stored along with people walking up there.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  3. #3
    Join Date
    Feb 2010
    Location
    Eastern MA
    Posts
    75

    Default Re: Insulation Help

    A 5% void in insulation results in a 50% reduction in effectiveness of insulation. You need to seal every penetration into the attic before adding any insulation as air infiltration is a significant cause of heat loss. I wouldn't add any insulation without sealing first. If you go the route of foam (your most effective solution), you will need to cover it for fire protection since you want to use the space for storage.

  4. #4
    Join Date
    Dec 2010
    Posts
    6

    Default Re: Insulation Help

    I have the same situation in my house in Nebraska. I was considering laying foam board insulation down on the plywood and then putting a layer of plywood on top of that so I could walk on it and still use the storage space. I'd like to know if this is a good idea? 2 inch thick foam board is about R-10, so with the r13 I have in between the joists I could get r23 or better if I add an additional layer of foam board. Any comments?

  5. #5
    Join Date
    Mar 2009
    Posts
    1,387

    Default Re: Insulation Help

    Howdy, the use of cellulose one advantage is it retards air infiltration. Another is the fire retardant included in it again fiberglass has none.
    How about donating some of the extra stuff or a garage sale and use the $ to add insulation...

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