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Fasteners and thermal bridging with exterior insulation – GreenBuildingAdvisor

  • February 4, 2025
  • Posted by: sherwin@eyeconz.com
  • Category: Uncategorized
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fasteners-and-thermal-bridging-with-exterior-insulation-–-greenbuildingadvisor

I’am planning on residing my house and have decided to add some exterior insulation while I’am at it.  I live in climate zone 6 in Maine and the house has 2×4 walls with kraft batts.  I ‘am planning on using cedar shingles for siding and will use zip R 9 or similar for my nail base with a rainscreen matrix. My question is will sending hundreds of siding nails through the exterior insulation when I apply the shingles negate some of the insulation value of the Zip R sheathing?  I’ve noticed a possible corollary with thermal images showing the interior side of walls with cold spots where the drywall screws are located. Thanks!!

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Replies

  2. DWest | | #2

    Malcolm,

    Thanks for the prompt and great reply! Some math is in order but I was particularly focused about the application of cedar shingles and the sheer number of nails I’ll be sending through the foam. Granted if i used 1 1/4 or 1 1/2 nails they wouldn’t penetrate more than a 1/2 into the foam.

    I estimate with a typical 5 inch reveal one square foot of shingle would have maybe 6-10 nails depending on shingle width. Cedar shingles is a classic New England detail but its application with exterior foam is a bit more nuanced than I would like. Thanks for link and I’ll keep digging for more info.

    1. Expert Member

      Akos | | #3

      The fact that the nails don’t make it through the foam makes a difference as well as the rest of the foam mitigates the thermal bridge. It also means if you ever go to reside you won’t a thousands of tiny holes through your air barrier.

  3. Malcolm_Taylor | | #4

    DWest,

    Is there any other realistic alternative for fastening either sheathing or cladding that doesn’t include some thermal bridging?

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