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Blown cellulose full of shredded plastic

kermit49 | Posted in Green Products and Materials on

Building what I think will be a better than a good enough house. Frankly got a lot of help reading here and Allison Bailes. Thank you.

House in Zone 3 southern Utah. Gets very hot here but with beautiful landscapes.

Using a lot of wet cellulose spray in the 10″ double stud walls. First pass went well, stuck to OSB, etc. Couple of days later, second pass not so well from a sticking point of view. What became very obvious was that there was an awful lot of shredded plastic, mostly from what appears to be shopping bags. 

My theory is that all those imbedded slippery plastic “sheets” interfere with the expected bonding of the paper based cellulose fibers. How can many of them stick together when there a slippery “wall” between them? Way too many sprayed bays topple, mostly slide down.

Contractor denies the second batch is different. Baloney. I am ALWAYS present when any build activity is taking place. I saw how well the first layer laid and no plastic.

QUESTION: is it good practice spraying so much shredded plastic on walls?

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  1. Expert Member
    BILL WICHERS | | #1

    I'm thinking they might have run the bags of cellulose through the blowing machine without opening the bag, i.e. they ran the ENTIRE bag of material through the machine instead of just the material inside the bag. I know this sounds dumb, but I've seen it happen!

    If you're having problems with adhesion due to the plastic, then the plastic bits are a problem. I don't see the plastic bits significantly affecting the insulating value of the material though. If the material is falling down/out, I'd make your contractor redo things, and double check the material before they run it through the blowing machine. You may have gotten a bad batch, or the contractor might be doing something wrong.


  2. Expert Member
    Joshua Salinger | | #2

    Your insulation contractor can specify the type of cellulose they are using. There are cellulose insulation products that are a higher grade that contain clean cellulose and borates. Other, cheaper cellulose insulation products contain plastics and debris. The latter is easier to process from the source material, typically post industrial and post consumer materials as the coatings on products, plastics, staples, etc. don't need to get separated before being processed into the insulation.

    It's possible your insulation contractor is unaware or just shopping by price and their supplier just gave them the cheaper stuff. I would ask to have the clean cellulose product supplied and would expect a premium pricing.

    It is likely that the debris is the source of the slumping, toppling and sliding. It shouldn't happen with the clean stuff. One can also add an adhesive to the wet mixture so long as the contractor has the correct equipment to handle this.

  3. kermit49 | | #3

    Hey guys, thanks for the valuable insight and tips.

    I am on site and never witnessed whole bags being sent to shredder. The plastic sheeting, I see imbedded in the cellulose is obviously store bags, all that was missing was sales receipts inside. Different colors and including candy wrappers.

    Installer likely picked cheapest cellulose he could find. The blown walls often slide down. Very time-consuming effort. I am willing to pay more for quality cellulose that will stick around long enough to let the drywall people do their part.

    Is there a cellulose manufacturer's website specifically for this industry? I need to learn more on the different grades of cellulose and where these grades are more effective.


  4. walta100 | | #4

    Seems like the most obvious and likely thing is that the contractor failed to add enough\any adhesive to the water when he installed the insulation. If you see plastic in the material maybe you need to add extra adhesive.


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