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I'm upgrading a home I bought

Jack Member Posts: 1,047
A couple years ago. Have done the hvac change out. The place still has knob and tube and a stunning assortment of substandard elec. I'm getting this repaired in Nov and as soon as power is done I want to get the place injected with some sort of foam. There are about R19 batts in the attic bot nary a bit in the wall cavities. What concerns should I have while the insulation cures...if any. In your opinion, what is the best insulation method/type?


  • Brad White
    Brad White Member Posts: 2,398
    My Default

    approach would be Dense-Pack Cellulose. I am looking into J-M "Spider", which is an improved short-fiber fiberglass with similar density to dense-pack cellulose.

    The key is density, not fluffing. Properly done, either insulation should be a firm, felt-like blanket to promote air blockage.

    Another type I have seen once is magnesium oxide foam, which has a very light "meringue" consistency and is said to be ok to blow in when you have knob and tube wiring. It goes in like shaving cream and hardens. I am not certain regarding R values but the air sealing qualities were stressed. I know only one person who has had it installed this past year and so far no experience/data.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"

    -Ernie White, my Dad
  • BillW
    BillW Member Posts: 198

    I also favor dense-pak cellulose ,properly treated with insect control, water repellent and fire retardant.  Offgassing from the older foam spray products and the particulate from the "shaving" process could be a problem, but now the products have evolved beyond that point. If you live in a bitter cold, windy place like the Adirondacks, North Kingdom in Vermont , U.P. Michigan or Minnesota, make sure the R values are at the design requirements for the area, and you have a heat loss done to make sure.  Same for more moderate climates.  Insulation is part of the equation for comfort and efficiency...too much or too little can be harmful.  Pick a reliable contractor with experience.
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