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Foam sheeting over wood plank siding on a 100-year-old+ home

curtisst | Posted in Energy Efficiency and Durability on

So my house need to be resided.
Over wood plank siding [Editor’s note: sheathing?] there are already 2 layers of siding
1st Clapboard
2nd cedar shakes .

As I get down to the wood planking it’s flat and clean a few loose boards .a screws tightens them back solid.

My question is ??
Foam or foil faced sheeting with taped joints to seal gaps in planking and
cut drafts and leaks
Or just a tyvec over planks and then apply a vinyl siding .?
I know that doing and old house always leads to trouble questionable situations ,,and
One can never do “the right thing”
But not to do some things is just wrong

Thank you for time and input

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  1. GBA Editor
    Martin Holladay | | #1

    It's always a good idea to tell us your location or climate zone.

    When you install new siding on your home, you have a once-in-every-50-years opportunity to upgrade the performance of your walls, so it's important to get the details right. The two most important things you can do are (1) make your walls more airtight, and (2) improve the R-value of your walls. You also have an opportunity to improve the water management details (flashing and water-resistive barrier) of your walls.

    These improvements are vitally necessary in cold climates (like the climate in Minnesota or Maine) -- less so in places like San Diego or Honolulu.

    Here on GBA, here is what we usually advise for cold-climate builders, from the outside in:
    - Siding
    - Vertical furring strips to create a rainscreen gap
    - A continuous layer of rigid insulation -- usually EPS foam, polyiso foam, or mineral wool
    - Housewrap
    - Sheathing

    You'll need to make sure that your rigid foam layer (if you choose to install rigid foam) is thick enough to keep your sheathing above the dew point during the winter. For more information on this issue, see Calculating the Minimum Thickness of Rigid Foam Sheathing.

    You will probably also want to read these two articles:

    How to Install Rigid Foam Sheathing

    All About Rainscreens

  2. curtisst | | #2

    Thank you .
    Sorry thought I did include . Zone 5
    Southern New England
    Thanks again

  3. curtisst | | #3

    Martin ,,Thanks again ..
    Quickly reading you replyes !!!!
    I guess the short answer
    Is Tyvec and a EPS or XPS and then my vinal
    With eps or xps the required thickness for r value

  4. GBA Editor
    Martin Holladay | | #4

    Q. "Is Tyvek and EPS or XPS, and then my vinyl, a good approach?"

    A. Green builders try to avoid the use of XPS, because it is manufactured with a blowing agent that has a high global warming potential. Either EPS or polyisocyanurate would be a better choice than XPS.

    Q. "With EPS or XPS, what is the required thickness for R-value?"

    A. The answer depends on the size of your studs. If your house is more than 100 years old, it probably has 2x4 studs -- but with an old house, you never know, so it never hurts to measure.

    In your climate zone, if you want to install exterior rigid foam, the foam layer would need a minimum R-value of R-5 for 2x4 walls (that's about 1 inch or 1.5 inch of polyiso, or 1.5 inch of EPS) or R-7.5 for 2x6 walls (that's about 2 inches of EPS or polyiso). All of these details are explained in my article, Calculating the Minimum Thickness of Rigid Foam Sheathing, which I urge you to read.

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