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Community and Q&A

What do the people on this site think of denim insulation?

Roger Smith | Posted in Green Products and Materials on

I am curious about the general concensus among the experts on using denim insulation bats to replace either ceiling or wall rockwool/fiberglass. I would probably use it in combination with .75″ or 1″ polyiso to bring up the R value.


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  1. Expert Member
    Dana Dorsett | | #1

    Denim batts are less itchy than rock wool or fiberglass, and have the same fire retardents as cellulose, but higher VOC. It's wicked expensive compared to other batts, more expensive (usually) than cellulose and will never fit as perfectly as blown or sprayed cellulose. It has some of the same hygric buffering benefits of cellulose.

    At - 0.75-1.0" polyiso won't be sufficient dew point control for an unvented roof assembly north of zone 3, and insufficient for dew point control in 2x6 wall assemblies north of zone 4, or even 2x4 assemblies north of zone 5. (At 0.75" it's not enough for even 2x4 assemblies in zone 5.)

  2. GBA Editor
    Martin Holladay | | #2

    You might want to read Tristan Roberts' classic 2008 report on cotton batts. Here's the link: Problems installing cotton insulation.

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