Applying Cellulose Insulation

I had an in depth talk with the lead technician who makes Cel Pac, one of the cellulose insulation manufacturers. I was discussing with him the topic of dense packing cellulose so that it does not settle and leave air pockets in the top of the walls. They suggest packing it to 3.5 pounds per square foot which is the same as putting a 3.5 pound 12’x12′ tile over a square foot of it.

The professional blowers have enough air pressure to create that packing density. The problem is that the local rental places sell blowers that are only made to blow the stuff into attics where dense packing is not needed and thus the blowers do not need to have pressure. And also they are usually used and abused which lowers their pressure further.

Since I didn’t want to invest in a $8k professional machine yet I was asking him about ways around the problem.

I also wanted a way around buying the par pac netting that you attach to studs and use to hold the cellulose, which would be an extra cost and also add a lot on the install time.

So I asked him a question that I wasn’t sure if he was going to hang up on me or answer:
“What if I put the sheet rock onto both sides of the wall and leave a space at the top. Then I fill the space with cellulose and pack it down with a two by four! Would this be crazy or would I achieve the same effect as par pack netting and an $8k machine?”

To my happy amazement his answer was YES! I thought that was just wonderful. I had found a solution that was low tech, effective, and affordable. That for me is green!

About the author: Gennaro Brooks-Church

2 comments to “Applying Cellulose Insulation”

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  1. Gennaro Brooks-Church - January 22, 2009 at 4:38 pm

    Hi,
    I don’t think it would take much more time to pack it. And getting it in and out is also something that can be figured out.

    Your idea is a good one. I like it.

    The whole need for packing the insulation has lessened for me, though. For the job I was speaking about I am using the cellulose for interior walls. Exterior walls have the poly iso board I have mentioned on other posts.

    And I was doing the cellulose more for sound proofing reasons than for insulation. Insulation on interior walls is good but not a deal breaker.

    But here is the thing. I have spoken to some good sound proofing people and they say that dense packing it actually AMPLIFIES sounds since the hard cellulose becomes a better transmitter of sound than loose filled cellulose.

    So I don’t need to dense pack it. And as to the danger of loose fill cellulose settling and leaving an air space at the top of the wall, that isn’t a big concern.

    As long as I pack it down just a bit it won’t settle much anyway. Maybe a couple inches over many years which won’t change the sound proofing nor will it matter for insulation.

  2. Keith Winston - January 22, 2009 at 3:13 pm

    And how exactly were you going to get the 2×4 in and out of that gap at the top of each stud bay? It’s a fine idea, but the challenge is doing an entire house in a reasonable amount of time (I’m assuming your own time is worth SOMETHING to you).

    Another possibility would be renting a low-end blower, and adding an inline blower to it, which can be bought for around $500 I believe. The rental unit stirs and breaks up and feeds the cellulose, and provides low back pressure, and the inline unit takes it up to dense-pak territory. I haven’t tried this yet but expect to (I own an ex-rental unit, a fairly decent one).

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