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Insulation retrofit mess

Phil_in | Posted in General Questions on

Hi folks, I’m a new poster but have been really appreciating the forum. I’ve been learning a lot from articles and posts but have some questions here that I’d welcome advice on. I hope it’s not too long-winded and that the images and sketch help.
I’m fixing up a 1-story 60’s ranch in northern Indiana (zone 5A) that we bought for my in-laws to live in next door to us. It has 2×4 framing and the plugs outside indicated the walls had insulation blown in. I planned to redo the siding in the coming years and focus on exterior insulation then (as well as dealing with the attic ventilation).
I’ve since uncovered original insulation consisting of some sort of continuous “quilt” (kraft paper exterior and foil interior sandwiching a thin layer of fiberglass) that appears to have been wrapped floor-to-ceiling around the whole house, over the studs and behind the plywood sheathing (see pictures). Any name for this product?
The insulation installer didn’t account for this and either: 1) never punctured the foil and just filled some of the fiberglass, or 2) punctured the cellulose and filled the bay pretty well, or 3) missed the bay altogether. This leaves me with a mess to deal with. My overall options appear to be:
1) Do the best I can blowing in additional cellulose to the unfilled bays from inside, behind existing drywall (see picture) – then rely on exterior insulation and air-sealing. 
2) Strip everything inside to sheathing, air-seal, blow in new cellulose, and rehang drywall on existing studs.
3) Tear down drywall, leave current insulation in place, and fur out wall  to add additional insulation and increase overall R-value in the process.

Removing the drywall would obviously simplify some re-wiring and plumbing, but most can be accessed or re-run through a solid crawl space so I wouldn’t do it otherwise. If I fur out the walls and have to do redo ceilings as well, I might use the opportunity to install some ventilation channels in the attic (that’ll be another post ;). Regardless I’ll re-plug and seal the insulation holes outside.
In terms of end-goal, there’s a long list of improvements and investments to be made so my goal for the walls is “pretty good”. 
Thanks for any input!

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  1. Expert Member
    BILL WICHERS | | #1

    I don't recognize that foil material, but I'll bet one of the other members here probably will. It is probably some kind of early housewrap-like material, maybe intended to provide some insulating value in sheet form a little bit like the 1/4" fanfold XPS.

    The insulation that was injected is a problem though. You have very poor fill in almost every stud bay visible in your pics. That's a problem. You could replace it from either side, so you'll need to decide if you want to reside now, and reinsulate from the exterior, or redrywall now, and reinsulate from the interior. If you're planning to replace the drywall anyway, I'd do that now and the exterior later, since that way you can finish the interior prior to move in, and you won't have messy, disruptive work to do on the interior later after you have tenants.

    Note that batts are easier to do DIY than dense pack. I wouldn't generally recommend trying to do dense pack if you haven't done it before. Batts are much easier to get right the first time, and don't require any special equipment to install wall -- you just have to take some care to get a good installation.


    1. Phil_in | | #4

      Thanks so much Bill for the good input on help. If I do anything with open bays I have someone I can bring in to blow in cellulose. If I leave the drywall in place, it'll be a more complicated job (identifying which bays, filling smaller voids, and trying not to further damage the foil) that I'll tackle with a contractor friend with more experience. Regardless, I'll deal with any interior insulation now from the inside so as not to have to remove the exterior sheathing.
      I guess the question I didn't directly ask is whether the old foil insulation provides any benefit as a barrier at this point or if it's more of a liability (even where bays were filled well) that I should just get rid of altogether.

      1. Expert Member
        BILL WICHERS | | #5

        I suggest you buy or rent an IR camera to identify which bays need work. An IR camera used on a hot (or cold) day will give you a sort of thermal X-ray vision allowing you to see where gaps and voids in the insulation with the walls are. This would probably save you lots of work.


  2. michaelbluejay | | #2

    Insulation being blown-in suggests an old house, which means there's probably lead paint. Make sure to follow lead-safe practices when doing any work on the siding.

    1. Phil_in | | #3

      Thanks, Michael. I'm testing as I go -- so far so good.

  3. seabornman | | #6

    When I retrofitted my house in zone 5, I ignored everything behind the sheathing, as my 1850s house had all sorts of construction, from batt insulation to nothing. I added 3" of XPS to the exterior, which has several benefits: it meets energy code all by itself, it protects any of the various wall constructions I have from condensation, and I didn't have to demolish interior finishes.

    1. Phil_in | | #7

      That makes sense to me. I'm less concerned about additional work inside, but with my plans to do exterior insulation anyways, I may as well look for the simplest path forward with respect to interior insulation. Thanks for your input.

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