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Community and Q&A

Cellulose in sidewalls with two ceilings

michaeldrehl | Posted in General Questions on

I have a house that was built in 1900s in NJ. It had high plaster ceilings. Over the years, we installed a lower drywall ceiling below the plaster ceiling. 

The sidewalls on the house are not insulated. I was thinking of cutting an opening in the drywall and pouring or using a machine to fill the cavities in the sidewalls with cellulose. 
I am afraid that I won’t be able to fill the cellulose to the height of the total ceiling. And also down the line, the cellulose will settle. 
Since I am heating the sidewalls only up to the drywall ceiling and not the plaster ceiling, is there a concern that mold will grow in the unfilled or settled cellulose cavity? 
Thank you for your help.


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  1. GBA Editor
    Martin Holladay | | #1

    Did you install any insulation above your new drywall ceiling?

    1. michaeldrehl | | #3

      Hi Martin,
      No, I haven't. I am planning to cut a opening in the sheetrock and slide fiberglass batts.

      Thank you for your reply!

      1. michaeldrehl | | #4

        Hi Martin, If you could let me know.

  2. Deleted | | #2


  3. GBA Editor
    Martin Holladay | | #5

    The empty stud bays of old, uninsulated wood-frame houses are routinely insulated with dense-packed cellulose. If you don't know these techniques, or are unsure whether you will be able to successfully implement the dense-pack method, I advise you to hire an experienced insulation contractor who is familiar with dense packing cellulose.

    If you want to do the work yourself, without learning dense-packing methods, you should certainly strive to fill as much of each stud bay as possible -- at least as high as the top of your ceiling insulation layer (not just to the level of the drywall ceiling).

    For more information on this topic, see "How to Install Cellulose Insulation."

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