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Community and Q&A

Insulation solution

thisisfrustrating | Posted in GBA Pro Help on

I have a unique situation and am looking for solutions.

I have a very cold & drafty old wood constructed home built in late 1800’s. The exterior frame is constructed of 2” thick vertical wood planks with 2” gaps between each plank covered with cedar shake shingle siding and “no insulation”. The shake shingles will be removed and over the exterior planks I’d like to install a breathable house wrap then insulation prior to installing (4’x 8’) P1-11 or Smart Panels. I could use 4’ x 8’ rigid foam sheets, but any thickness with these will create a “thickness issue” with the inset of windows & doors.

Ideally I’d like to find a “thin combination” of a breathable house wrap (allowing inside vapor to escape & as well as air flow space) that also has a high R value as rigid foam sheeting.

Thanks, Paulette

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  1. Expert Member
    Peter Yost | | #1

    Hi there TIF (be great to have a real name for the GBA Q&A community) -

    I know at least one manufacturer working on incorporating aerogel insulation into or integrating with a housewrap but still under development.

    Stay tuned - Peter

    1. charlie_sullivan | | #3

      I hope that is a better product than the infamous insult-ex housewrap.

  2. Expert Member
    BILL WICHERS | | #2

    I think physics is not your friend here. You’re not going to find housewrap that performs at anything even a tiny bit close to the worst rigid foam on the market.

    The best performing rigid foam board per inch is polyiso. You need to make sure to use enough for your climate zone so that you don’t create new moisture problems within your wall. The polyiso will also do a good job as an air barrier if you tape and seal it well, although many people like to use a layer of housewrap too.


  3. Expert Member
    Peter Yost | | #4

    I hear you guys but believe it or not, I have it from a very trustworthy source that R10 - R13 for just 3/8-inch thick. I know it sounds crazy and when the test results came back this manufacturer had a leading building science firm doublecheck the results: solid.

    Stay tuned...

    1. Expert Member
      BILL WICHERS | | #6

      That’s getting up close to theoretical values. In our depressing world of physics and engineering, as we approach theoretical maximums (or minimums, whichever we need), we approach infinite cost. Everything ends up being a tradeoff. In my expierience as an engineer, someone always complains and blames you for whichever trade offs you made too...

      Anyway, I’m guessing you’ve heard whispers of some kind of aerogel supported vacuum insulated panel. If that becomes a real thing, or at least a “we’ll have it for sure in 3Q2019” real timeline to production kind of thing, please make sure to put a big flashy article up so that none of us miss it!

      I’ll keep my fingers crossed that the product is successful and affordable too.


  4. Expert Member
    Peter Engle | | #5

    Aerogels have been around for about 40 years now, probably longer, just looking for a good application. These, and vacuum insulated panels seem to be technologies that are perenially "just around the corner." Passing the bar of high insulating value AND reasonable economic value seems to be a difficult lift. I'll certainly stay tuned, but I won't be holding my breath.

    As far as Paulette is concerned, none of them is going to help her out much.

  5. thisisfrustrating | | #7

    Thank you ya'll. ... A bit off the beaten patch......sorry I asked as no one has alternative solutions or advise.

    1. GBA Editor
      Martin Holladay | | #8

      I agree with Bill / Zephyr17. Insulation is generally in the range of R-4 to R-6.5 per inch. So if you are looking for R-14 to R-20 -- and you should be -- that takes a few inches.

      A skilled carpenter can add thickness to a wall, and still accommodate existing doors and windows, but the flashing issues get complicated, so you need to find a builder you can trust.

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