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Bonfiglio wall insulation question

jollygreenshortguy | Posted in Energy Efficiency and Durability on

A question about insulation materials availability –
I’m an American, now living in France, but still doing some work back in the States. Here in France you can buy gypsum wallboard with a layer of EPS insulation bonded to the back face. It’s available in a range of EPS thicknesses, from around 1/2″ to 4″. It’s typically used on the inside of CMU walls, which is the standard residential wall construction here.
I became aware of the Bonfiglio wall here on GBA just the other day. It seems like the 1/2″ or 1″ EPS wallboard would be ideal for breaking the thermal bridging at studs, without introducing too much of a vapor retarder effect on the interior face.
Does anyone know if this kind of wallboard is available in the USA? It’s standard stuff at the retailers here in France. If it’s not available yet in the USA this seems like a major market opportunity.
Here is a typical example:

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  1. Expert Member


    Bonfiglioli walls are a bit different than what you are describing. They have strips of insulation covering the structural wall members, rather than a continuous layer of foam.

    Interior foam works fine, although most people who decide to include foam on a wall put it on the exterior where it helps keep the sheathing warmer and safer.

    The minor downsides to using interior foam I can think of are that anything over 3/4" thick makes installing electrical boxes and cabinets more difficult, and necessitates changing the standard framing details at interior corners and wall intersections.

    1. jollygreenshortguy | | #3

      Thanks, Malcolm. I understand the difference. Bonfiglio gets long narrow strips of insulation and attaches them to wood strips before then attaching the wood strips to the studs. And finally he adds drywall over that. I brought this up because that's 2 extra steps of labor between framing and drywall, while with the panels I described, there are NO extra steps. Indeed, the foam is continuous rather than just at the studs, but again, by keeping it to just 1/2" it doesn't become a significant vapor retarder and doesn't complicate installing of electrical boxes.

      1. Expert Member
        MALCOLM TAYLOR | | #4

        At 1/2" it sounds like there are none of the problems I worried about. I wonder why it hasn't caught on here?

  2. rkymtnoffgrd | | #2

    I considered utilizing 1.5" rips of ZipR for a bonfiglioli wall configuration but it would have required a significant change in the workflow for the trades... This is due to exactly what Malcolm was alluding to, having to convert from nailed gang boxes to "remodel" type that were installed after the drywall was hung. How then are electrical rough in inspections done... IDK, It just seemed very complicated and I gave up on the pursuit.

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