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Community and Q&A

How much for damp-spray cellulose?

Patrick Mccombe | Posted in Green Products and Materials on

Can anyone with experience contracting damp-spray cellulose please tell me what it costs generally? Some project details would also be helpful. I’m researching a story for Fine Homebuilding magazine and it’s tough to get pricing for damp-spray.

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  1. GBA Editor
    Martin Holladay | | #1

    Whatever information you gather, remember that prices vary WIDELY from region to region. I have noticed that price variations are particularly acute for cellulose. In some areas, cellulose is common and affordable. Elsewhere, it is rare and expensive.

    Here's information copied from a comment posted over a year ago (click here for a link to the thread) by GBA reader Danny Kelly, who lives in North Carolina:

    "Hi Martin - just recently did this exercise for a presentation I was doing for some architects - here are a few for NC - all prices are per square foot installed and include the 15% price increase we got last quarter:
    kraft faced fiberglass batts:
    R-15 - .49
    R-19 - .41
    R-30 - .63
    R-38 - .71
    R - 30 blown - .48
    R-38 blown - .58
    Blown in fiberglass walls
    2x4 wall - .65
    2x6 wall - .90
    Damp spray cellulose in walls
    2x4 - .58
    2x6 - .81
    Open cell foam
    2x4 - 1.00
    2x6 - 1.40
    roof rafters 5.5" (I know, I know, but that is what everyone does down here) $1.40 plus .75 when ignition barrier is requuired
    Closed cell:
    2" - 1.75
    3" - 2.50
    12" netted cellulose for double stud wall - $2.00
    We get prices all over the place from one company to the next even locally, interested to see where others are coming in.
    Answered by Danny Kelly"

  2. GBA Editor
    Patrick Mccombe | | #2

    I followed the link. Danny is the only poster who mentions damp-spray. I wonder why it's so rare.

  3. GBA Editor
    Martin Holladay | | #3

    A lot of builders are wary of an insulation method that adds moisture to the wall assembly.

  4. Expert Member
    ARMANDO COBO | | #4

    Damp-spray cellulose will shrink after it dries, leaving a small gap between the cellulose and the framing members.

  5. GBA Editor
    Patrick Mccombe | | #5

    Why does this photo look like it's been photo-shopped Armando?

  6. GBA Editor
    Martin Holladay | | #6

    Those are two photos -- one on top of the other. (Unfortunately, the GBA site doesn't insert any white space between photos when readers post multiple photos.)

  7. Expert Member
    ARMANDO COBO | | #7

    Those are untouched real photos, from a real jobsite, that had been approved by a third party rater and building inspector. Is the same location, just one is a close-up. I think I posted several pictures of that same job on another thread here at the GBA.

  8. Expert Member
    Dana Dorsett | | #8

    The amount of shrinkage of damp spray depends on the moisture content and density when sprayed, as well as the rate of drying. It's typically still tighter than batt installations, and it can be dense-packed with no apparent shrinkage or settling over time, but dense packing is more labor intensive and costs more.

  9. wjrobinson | | #9

    Gap only on one side of 2x4 for whatever reason.

  10. wjrobinson | | #10

    What is the density of wet spray?

  11. Expert Member
    Dana Dorsett | | #11

    I agree there are a number of mechanisms that could cause the separation. But with dense pack the springiness of the cellulose wouldn't allow that unless the stud moved a LOT!

    But it's something to be aware of and inspect for when using damp sprayed cellulose. Cobo has stopped using damp spray altogether after discovering gaps using IR imaging many months after the house was finished.

  12. Jon_R | | #12

    Looks to me like a case of a stud moving, not shrinkage. Note the cross member and how the gap is largest at the cross member and then tapers away. No gaps anywhere else.

    One doesn't have to look hard to find examples of defects in any kind of insulation when installed incorrectly. I expect that with proper moisture levels (during spraying) and adhesive, damp sprayed cellulose reliably has no gaps.

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