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Possible to dense pack cellulose by hand?

Gainsolarman | Posted in General Questions on

Zone 3a/4a right on the line….

I am renovating an 1870’s balloon framed farmhouse.  I am residing the house and thus opening it up from the exterior.  Doing this one wall section at a time.  While I have the walls open I am insulating from the outside.  I hate fiberglass.  I’ve already successfully dense packed a number of the wall cavities with the following method….

1.  rip plywood in 2×8 sheets and fasten longways to wall.
2. hand pour/pack cellulose in cavities
3. tamp with 2×4 until tightly packed/cant pack anymore
4.  I’m calculating the cubic footage of the wall cavities as I go and comparing to # of bales of insulation ive used and I’m averaging  aroud 4 lbs per cubic foot

What is wrong with doing it this way other than it being time consuming?
Am I missing something?

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  1. Expert Member
    Dana Dorsett | | #1

    >"2. hand pour/pack cellulose in cavities
    3. tamp with 2×4 until tightly packed/cant pack anymore
    4. I’m calculating the cubic footage of the wall cavities as I go and comparing to # of bales of insulation ive used and I’m averaging aroud 4 lbs per cubic foot"

    4lbs is a density beyond where it's R/inch will be going down, not up, and won't be as consistent, but it's way better than nothing. The sweet spot for cellulose performance is an even-density( not lumpy), though in colder climates 3.5lbs may be necessary to prevent settling in 2x6 wall cavities. In zone 3A something like 3-3.2lbs would be enough.

    It's possible to dense pack to 2.8lbs+ with a single stage rental blower if there is enough room to fish the hose all the way up or down into the cavity, though it's easier using narrower 1-1.25" I.D. dense packing tubes. With a balloon frame you'd have to install air barriers on the open cavity tops (and bottoms, if open). Corrugated cardboard stapled to the framing with a X cut into it for inserting the dense packing tube can work pretty well when dense-packing to less than 3.5lbs.

    Don't rule out "2- hole method" lower density cellulose, which usually ends up around 2-2.5 lbs. If lower density cellulose settles over a decade or so it can be topped off. On a full-gut rehab project I've seen 2-hole method cellulose that hadn't sagged a bit in a 2.5 story balloon frame 30 years after installation. It looked like it could have been installed 30 hours (rather than years) prior.

    1. Hammel_Shaver | | #3

      Thanks for the answer Dana. Wondering why you said cellulose needs a higher density to prevent settling in cold climates. It is more prone to settle in clod climates?

  2. user-6184358 | | #2

    I hand installed cellulose in rafter bays from the top. - I put the cellulose in a large box, then used a drywall compound mixer on a drill to fluff the insulation prior to installation. I got very close to the volume listed on the bag.

  3. Hammel_Shaver | | #4

    I've thought about doing this same thing myself. Have your done any thermal imaging or other testing to check the results over time?

    I dense packed 2 walls of a 10x10 addition with a HD Blower that comes free with the cellulose purchase.

    I retrofitted a 1 1/2 tube to the end of the hose and retrofitted a baffle into the hopper of the Blower machine so it could only send 1/3rd as much cellulose through the hose as it would have. This gave it a higher blow to cellulose ratio.

    This method took a very long time do to the restriction of cellulose being blown (Not to mention the many times the machine jammed because of the baffle) It took me about 8 hours to dense pack 20 feet of 8ft tall 2x6 wall.

    The installation access points where a hole cut in the sheathing mid way up the wall at each stud cavity.

    I'm 2 to 3 years out (hopefully) from a design build and would like to try the hand packed dense pack method on a double stud wall system. Any thoughts on how you would approach that given your experience with your retrofit?

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