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  1. #1
    Join Date
    Jan 2011
    Posts
    2

    Default exterior wall insulation

    Hello everyone,
    This is my first post. I would greatly appreciate any insight to my query. Our home was built in 1903 and at some point in the history of the house, a previos owner had the exterior walls filled with expandable foam, which has since shrunk and separated in various places (determined by an I.R. camera). I need to replace the cedar shake siding come spring and am considering removing the sheathing underneath to expose the framing. I am considering removing the foam and replacing it with R-15 fiberglass batt, then covering with 1" polystyrene sheets and finally wrapping with tyvec before replacing the sheathing and new cedar siding. Does anyone think that this is worth the effort or have any other suggestions? Thanks so much for your help.

    Steve

  2. #2
    Join Date
    Jan 2009
    Location
    Needham, MA
    Posts
    559

    Default Re: exterior wall insulation

    if you're in massachusetts you'll have to up the R value in the exterior walls to 20 if you're going to do that. if r-15 is acceptable in your state, that sounds like alot of work.

  3. #3
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: exterior wall insulation

    Quote Originally Posted by genesisguitars View Post
    Hello everyone,
    This is my first post. I would greatly appreciate any insight to my query. Our home was built in 1903 and at some point in the history of the house, a previos owner had the exterior walls filled with expandable foam, which has since shrunk and separated in various places (determined by an I.R. camera). I need to replace the cedar shake siding come spring and am considering removing the sheathing underneath to expose the framing. I am considering removing the foam and replacing it with R-15 fiberglass batt, then covering with 1" polystyrene sheets and finally wrapping with tyvec before replacing the sheathing and new cedar siding. Does anyone think that this is worth the effort or have any other suggestions? Thanks so much for your help.

    Steve
    Steve --- kudos for having the IR camera work.
    If you want to proceed with your plan it can work out nicely --- no destruction from interior.
    What you describe regarding the foam is one reason I'm not a fan of a *pour in* method for foam.

    Anyway, you might consider ,once removing the exterior siding/sheathing, leave the existing foam in place. As long as it's sound have a company come out and fill the voids with a spray in foam. Otherwise it will bear a bear and messy trying to remove the old foam.
    Re-apply sheathing add the house wrap and the layer of rigid foam. The rigid foam on the exterior needs to be an appropriate thickness for your region to be effective.
    Once you have everything in place you'll benefit from the thermal break the exterior foam will provide --- increasing the performance of the wall anywhere from 25-65% ( depending on thickness of exterior rigid foam. )
    "" an ounce of perception -- a pound of obscure "
    - Rush

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