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Improve air sealing and thermal insulation at an unusual ceiling to wall detail

raccuia | Posted in Energy Efficiency and Durability on
I have an air sealing and thermal insulation dilemma. I live in Dublin Ohio and my home was built in 1984.My home is 2X4 platform framed with brick and stucco exterior and asphalt shinged roof.
In the winter my second floor gets cold along the south and north wall. And my first floor ceiling gets cold  also in the same locations. I recently replaced a first floor ceiling can lite near the south wall and was able to take a photo looking south between the second 2X10 floor joist, there appears to be insulation stuffed between the floor joist at the area where the second and first floors are offset, see attached. I also made a sketch up model building section looking west showing the existing framing at the north wall and south wall. 
How can I air seal and better insulate these areas without removing my finished drywall ceiling and crown moulding?
Joe Raccuia

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  1. Expert Member


    There is no easy answer. You need access to improve the air-sealing and insulation. That comes from opening up the bays from the inside or exterior.

    The one identified as detail 3 might be addressed by adding a layer of rigid foam to the soffit, after air-sealing and filling the bays with batts. Detail 2 is a more complex. It's hard to say which is the least disruptive access path. I suspect removing some drywall on the bottom of the second floorwall is probably the easiest. After that, a few holes cut in the subfloor should allow you to insulate the joists bays.

  2. ColdJoe | | #2

    I am in a similar pickle, and have spent a good amount of time researching options. Malcolm is spot on, but I want to throw out a few other considerations and questions.

    If maintaining your finished drywall ceiling and crown moulding are the priorities, then you'd probably want to access these areas from the exterior. Look up on youtube "airsealing soffit overhangs" and you'll see how others access the area externally to either sprayfoam it, or cut rigid foamboard to size and seal around that with expanding foam.

    But this makes me wonder what type of material is covering your soffits? Hopefully something easy to remove like aluminum or vinyl siding. You mentioned brick and stucco and if that's what's on the underside, then it might be more difficult to access.

    One final oddball thought is maybe to access area 2 you could make holes at the bottom of the 2nd floor wall, do your airsealing. And then cover up the drywall damage with baseboard trim. Just spitballing here, I haven't fully thought this through.

    1. Expert Member
      MALCOLM TAYLOR | | #3


      It's a bit of a puzzler isn't it? Part of what decides where you access from depends on how comfortable you are with the re-finishing afterwards. I don't mind patching drywall at all, so that would be my chosen route, but maybe that's not a common preference.

      I once had to patch a head-shaped hole in the wall of a ju-jitsu gym where someone tossed me through it.

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