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Musings of an Energy Nerd

Two New Exterior Insulation Products for Walls

InSoFast sells EPS foam panels with integral plastic furring strips, while Tyvek has introduced a squishy quilted housewrap

InSoFast EX 2.5 panels are made of expanded polystyrene (EPS). The grooved panels are 2 1/2 inches thick and are rated at R-10. The panels contain embedded vertical "studs" made of polypropylene to facilitate fastening the panels to walls and to facilitate fastening siding to the panels.
Image Credit: InSoFast

Exterior wall insulation? That usually means rigid foam and furring strips — although occasionally, it means mineral wool insulation and furring strips.

But there are other options. Two new products offer builders new ways to keep their wall sheathing warm.

InSoFast EX 2.5 insulation panels

InSoFast panels — rectangles of expanded polystyrene (EPS) foam with embedded plastic “studs” that hold drywall screws — have been around for years. The product was developed as a quick and convenient way for homeowners to insulate the interior of basement walls. The company’s original product (the InSoFast UX 2.0 panel) is 2 inches thick and rated at R-8.5.

InSoFast is now promoting a thicker panel, the InSoFast EX 2.5 panel, for use on the exterior of wall sheathing. (In many ways, the InSoFast EX 2.5 panels resemble the Quad-Lock R-etro system. For more on Quad-Lock R-etro, see my review in the fourth issue of GBA’s Insider magazine. GBA also lists the Quad-Lock R-etro system in our Green Products Guide.)

Each InSoFast EX 2.5 panel measures 24 inches by 48 inches by 2 1/2 inches thick. The EPS has a density of 1.25 pounds per cubic foot. The panels have tongue-and-groove joints around the perimeter that are described as “self-flashing.” While these joints are designed to shed water, the foam panels have not been approved for use as a water-resistive barrier (WRB), so builders will still need to install a layer of housewrap or asphalt felt to protect the wall sheathing.

The new 2 1/2-inch-thick panels have several features that differ from the original 2-inch panels designed for interior use:

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  1. kevin_in_denver | | #1

    Vinyl siding over a
    Vinyl siding over a pillow?

    How embarrassing for Dupont.

  2. GBA Editor
    Rob Wotzak | | #2

    I wonder if...
    I wonder if the DuPont engineers got any inspiration from the SCI-Arc and Caltech 2011 Solar Decathlon house. Although that house's exterior blanket is the cladding:

  3. jinmtvt | | #3

    seriously Dupont ???
    euh ... is that some kind of joke ? i thought it was an early april fool or something ..

    But, nice to see finally some EPS manufacturers to come out with early attemp to exterior insulation panels with embedded strips !!! Now we need more and thicker solutions .

    afterthought ..
    is it really necessary to have fasting strips with only 2.5" thick ?
    i'd rather install regular strips screwing through everything directly in studs if possible at that thickness .. nah ?

  4. nvman | | #4

    DuPont thermocrap
    I can't see it working well with vinyl siding.

    What happens if something hits the siding and bends a nail?
    Or if the siding catches on an imperfection on the nail?
    And what about corners? The nail slots are usually vertical so that top nail better be in perfect.
    I see just too many things to go wrong.

    I also don't like the response from Dupont's Jim Ash.
    I have heard a similar response from builders/installers when trying to deflect critisicm about a crappy install or product.

  5. mfredericks | | #5

    ThermaWrap R5.0 and insulated battens
    Here's a video clip from Matt Risinger who shows a mock up of the ThermaWrap product installed with the insulated battens.

  6. GBA Editor
    Martin Holladay | | #6

    Response to Mark Fredericks
    Thanks for the link. It's handy to see a mockup with the Insulated Battens. I have embedded the video in the blog.

    1. erlybird | | #7

      Any current updates on InSoFast EX 2.5 insulation panels?

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