+ Reply to Thread
Page 1 of 2 12 LastLast
Results 1 to 10 of 17
  1. #1
    Join Date
    Dec 2009
    Location
    Ithaca, NY
    Posts
    2

    Default Adding even more attic insulation

    I have two layers of R19 fiberglass insulation in my attic. One layer is paper faced and installed in the rafter bays with the paper side down. The other layer is unfaced and installed across the rafters (i.e. 90 degrees to the bottom layer).

    That was good enough 15 years ago when I installed the second layer, but I would now like to install at least another R19 on top of what I already have. My question is can I install another layer of unfaced R19 on top of the two layers I already have? (I worry that this might compress the two lower layers.) If I can should I install it at 90 degrees to the top layer?

    Also, is three layers of R19 enough for a cold climate (upstate NY), or would it pay to add more than R19 as long as I am at it?

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

    Default Re: Adding even more attic insulation

    Quote Originally Posted by dll View Post
    I have two layers of R19 fiberglass insulation in my attic. One layer is paper faced and installed in the rafter bays with the paper side down. The other layer is unfaced and installed across the rafters (i.e. 90 degrees to the bottom layer).

    That was good enough 15 years ago when I installed the second layer, but I would now like to install at least another R19 on top of what I already have. My question is can I install another layer of unfaced R19 on top of the two layers I already have? (I worry that this might compress the two lower layers.) If I can should I install it at 90 degrees to the top layer?

    Also, is three layers of R19 enough for a cold climate (upstate NY), or would it pay to add more than R19 as long as I am at it?
    Basically the answer is -----Yes to what you are proposing.
    There will be a slight compression of the bottom most layer but, really not much to worry about.


    Hopefully this helps.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  3. #3
    Join Date
    Feb 2008
    Posts
    69

    Default Re: Adding even more attic insulation

    My suggestion would be to blow loose insulation over the top of everything. That will seal all existing cracks around the existing insulation, On top of that, it will be much faster, easier, and will probably cost less, plus be lightweight. As far as insulation is concerned in cold climates, like mine in Minnesota, more is always better. Heating and cooling costs will be greatly reduced by adding insulation.

    Enjoy a nice warm winter.

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

    Default Re: Adding even more attic insulation

    Quote Originally Posted by jkirk View Post
    to go a little deeper than canuk just saying yes, by making the next layer at 90 deg, it will cover the joint between the batts laying side by side which reduces heat loss at those seams
    What ?!?!?
    A single word answer isn't good enough ?
    Geez .... I get razzed when providing a detailed answer and when trying to keep it simple I get razzed ----- can't win.

    Jkirk is bang on with his reply.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  5. #5
    Join Date
    Aug 2009
    Posts
    62

    Default Re: Adding even more attic insulation

    Yes to what everyone is saying. Lowes and possible Homedepot will rent the insulation blower for free if you get 10 bags or more of cellulose insulation a lot of times. It shouldn't be to expensive and should be pretty quick to blow on a layer of R10-R20 insulation over everything if you want. Or you could just lay another layer of R19 on top of everything. If the cost isn't much different, why not get R30 though?

    At least based on Lowes.com prices their R-19 is almost the exact same price as R-30 for the rolls of batting (unfaced).

  6. #6
    Join Date
    Dec 2009
    Posts
    5

    Default Re: Adding even more attic insulation

    I'm going through an insulation upgrade, too. One of the things I did was install insulated shades in my cold rooms. They work amazingly well, but while I was on their web site (windowquilt.com) I came across an eye-opening fact (I poked around the web and verified it) about R-value: Your gains drop off dramatically after about R15. In fact, adding a third layer of R-19 will do virtually nothing for your energy bill! If I'm wrong, can someone point me to some data showing otherwise? I don't want to go off spending money that I'll never see back through lower utility bills. Thanks.

  7. #7
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: Adding even more attic insulation

    Quote Originally Posted by bob322 View Post
    I'm going through an insulation upgrade, too. One of the things I did was install insulated shades in my cold rooms. They work amazingly well, but while I was on their web site (windowquilt.com) I came across an eye-opening fact (I poked around the web and verified it) about R-value: Your gains drop off dramatically after about R15. In fact, adding a third layer of R-19 will do virtually nothing for your energy bill! If I'm wrong, can someone point me to some data showing otherwise? I don't want to go off spending money that I'll never see back through lower utility bills. Thanks.
    I can't begin to say how much I disagree with you.

    Perhaps you might do some more research in order for you to gain a better understanding as to the dynamics and benefits of insulating your home.

    Start with this article from your own Dept. of Energy ...........
    http://www.ornl.gov/sci/roofs+walls/...on/ins_01.html

    There are minimum and maximum recommended values published by the government for what their projected levels are based on region , costs of fuels , materials , etc.. ---- weighing the cost benefit of insulating versus the cost of energy lost from the structure.

    Which by the way are far higher than what you posted ---- regardless of region.

    Keep in mind the idea behind insulating is keeping your living space conditioned with respect to the outside elements maintaining a comfortable lifestyle ----- minimizing the cost of energy to do so.

    Simply ----- the materials used for insulation provide a resistance to heat loss and heat gain ---- depending on the season. The more insulation ---- the more resistance to the loss or gain ---- the longer and easier to condition your living space for your comfort while using less energy to do so which cost you less money.

    Can you reach a point of no return on your investment for over insulating ?

    In some regards --- yes.

    Whether you live in Vancouver - Washington or Vancouver British Columbia ----- you wouldn't necessarily insulate to the same levels as a home in North Dakota or the Canadian Prairies.
    However --- If you could condition your living space with minimal or no cost of doing so with mechanical equipment ---- is this over insulating?
    Also , once that insulation is in place it doesn't cost a dime to operate and will continue to perform without costing anything extra.


    2 cents .
    "" an ounce of perception -- a pound of obscure "
    - Rush

  8. #8
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: Adding even more attic insulation

    Quote Originally Posted by reenieandrod View Post
    My suggestion would be to blow loose insulation over the top of everything. That will seal all existing cracks around the existing insulation, On top of that, it will be much faster, easier, and will probably cost less, plus be lightweight. As far as insulation is concerned in cold climates, like mine in Minnesota, more is always better. Heating and cooling costs will be greatly reduced by adding insulation.

    Enjoy a nice warm winter.
    This would depend on what the losse fill is.
    If it was loose fill fiberglass then perhaps this may work fine.

    If the losse fill was dense pack cellulose I wouldn't recommend it.
    Mainly because of the weight of the blown in would compress the batt insualtion. By doing so will greatly reduce the R value of the batts and reducing the overall value even with the blown in.
    If you decide to add blown in I would pull up the batts ---- blow in the loose fill then cover that with the batts.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  9. #9
    Join Date
    Dec 2009
    Posts
    5

    Default Re: Adding even more attic insulation

    Interesting! Here's what I've been seeing: http://www.buildings.com/ArticleDeta...1/Default.aspx

    I've seen a similar graph in many different places. I'm all for insulating the heck out of everything, but this inidcates that the incremental benefit of going over R-20 is minimal. I would rather spend the money on additional energy saving measures that would have more effect.

    If you step back and just look at the data, it looks to me that blindlin adding R-value at the expense of other measures is counterproductive. I know it seems to go against most of what's in the press, but it sure looks that way to me!

    Quote Originally Posted by canuk View Post
    I can't begin to say how much I disagree with you.

    Perhaps you might do some more research in order for you to gain a better understanding as to the dynamics and benefits of insulating your home.

    Start with this article from your own Dept. of Energy ...........
    http://www.ornl.gov/sci/roofs+walls/...on/ins_01.html

    There are minimum and maximum recommended values published by the government for what their projected levels are based on region , costs of fuels , materials , etc.. ---- weighing the cost benefit of insulating versus the cost of energy lost from the structure.

    Which by the way are far higher than what you posted ---- regardless of region.

    Keep in mind the idea behind insulating is keeping your living space conditioned with respect to the outside elements maintaining a comfortable lifestyle ----- minimizing the cost of energy to do so.

    Simply ----- the materials used for insulation provide a resistance to heat loss and heat gain ---- depending on the season. The more insulation ---- the more resistance to the loss or gain ---- the longer and easier to condition your living space for your comfort while using less energy to do so which cost you less money.

    Can you reach a point of no return on your investment for over insulating ?

    In some regards --- yes.

    Whether you live in Vancouver - Washington or Vancouver British Columbia ----- you wouldn't necessarily insulate to the same levels as a home in North Dakota or the Canadian Prairies.
    However --- If you could condition your living space with minimal or no cost of doing so with mechanical equipment ---- is this over insulating?
    Also , once that insulation is in place it doesn't cost a dime to operate and will continue to perform without costing anything extra.


    2 cents .

  10. #10
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: Adding even more attic insulation

    Quote Originally Posted by bob322 View Post
    Interesting! Here's what I've been seeing: http://www.buildings.com/ArticleDeta...1/Default.aspx

    I've seen a similar graph in many different places. I'm all for insulating the heck out of everything, but this inidcates that the incremental benefit of going over R-20 is minimal. I would rather spend the money on additional energy saving measures that would have more effect.If you step back and just look at the data, it looks to me that blindlin adding R-value at the expense of other measures is counterproductive. I know it seems to go against most of what's in the press, but it sure looks that way to me!

    Ya know ---- I had prepared quite a lengthy responce to your theory but decided there's no need to ---- afterall , I'm just some guy posting on a forum over the internet.


    However, the article you provided isn't a reliable source to draw your conclusion upon ---- in my opinion.

    The one thing I get from reading that article is from the perspective of roofing contractors trying to cut costs.
    While some of the information regarding insulation is true it's also incomplete.
    Anyone can manipulate facts to favour their side such as what I see in that article.

    For example ----- dimensional lumber is assigned a value of R-1 per inch of depth. ( it can vary but 1 is the typical value for discussion ).

    Based on that ------- if your ceiling joists are 2x8 ---- one could say there is a R value of approximately R-7.5 for the ceiling.

    That is an incomplete statement since the ceiling is a system --- the 2x8 joists and the spaces between the joists are components that make up the entire ceiling system.

    While there is approximately R-7.5 for the joists the uninsulated spaces between them have a far lower value ----- perhaps R-1. When the entire system is evaluated the total is not R-7.5 but rather in the neighbourhood of R-2.5.

    You can see how the results differ when the story is complete.

    There are far more complexities and variables that come into play within the building dynamics that affect thermal transfer in terms of heat gain and loss than that article hadn't even hinted or touched.

    Once again if you follow the advice in crediable publications like this.........
    http://www.ornl.gov/sci/roofs+walls/...on/ins_01.html

    they are based on facts and not hype .

    There is considerable and reliable information based on countless research studies by many groups that conclude the same things regarding thermal insulation ------ as well the real world experience in millions of homes across the globe.


    It's your nickel.
    Last edited by canuk; 12-29-2009 at 09:21 AM.
    "" an ounce of perception -- a pound of obscure "
    - Rush

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •