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Slimmest Blown Cellulose Insulation Cavity?

user-974279 | Posted in Energy Efficiency and Durability on

Another question here. Hoping someone from the insulation community can give me an answer.

What is the slimmest insulation cavity that can be blown? Is it possible to blow 1.5″ to 1.75″ thick cavities? It seems like you could…you would just have to have a hose that was small enough right?

The reason for the question: if I wanted to build a strapped wall, install an air barrier between the strapping and the studs, and then fill that 1.5-1.75″ cavity with more insulation could I do it? I realize I could probably use fiberglass batts for this but let’s just say I don’t want to.

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  1. GBA Editor
    Martin Holladay | | #1

    I imagine it would be possible to blow cellulose into a 1.5-inch cavity -- but I'm not sure whether it would be a good idea. I have forwarded a link to your question to cellulose expert Bill Hulstrunk; he's the best person to answer the question.

  2. user-974279 | | #2

    Thanks for doing so. Am I wrong in saying that cellulose seems to be more of an East Coast thing? It appears that most of the producers of cellulose are in the midwest and east. There are a few over here but where you buy there products I don't know. Green Fiber is available at HD but is a lot more expensive than Fiberglass. I think Knauf's Smart Shredz may be available from some contractors but it's pretty hard to find retail.

  3. Bill_Hul | | #3

    Hello Spencer,

    For cavities narrower than 1.5 inches we generally fill with a foam gun. I have made up smaller installation tubes out of black plastic water line, but the smaller your tube, the longer it will take to fill and the more likely you are to clog your hose.

    In regards to availability, cellulose insulation is available nationwide and the Cellulose Insulation Manufactures Association (CIMA) has a list of manufactures located at

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