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Subfloor insulation material?

user-894335 | Posted in Green Products and Materials on

I am building a new house and plan to use Green Fiber cellulose for wall (dense packed) and attic floor (loose) insulation. I was told that cellulose does not work for subfloor insulation. We have raised foundation with 2′ vented crawl space in California.

I don’t mind using fiberglass in closed cavity walls and plan to use it for interior walls for sound barrier. However, I prefer not to use fiberglass for subfloor insulation. Is there any other alternative?

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Rian,
    Some crawl spaces are damp. For that reason, I suggest that you install rigid polyisocyanurate insulation on the underside of your floor joists. Do a good job of air-sealing the polyiso seams, as well as the perimeter of the insulation.

    If you feel confident that your crawl space will be dry, you could install dense-packed cellulose in the joist bays above the polyiso. However, since most floor joists include plumbing pipes (with their periodic leaks), there is a certain logic to skipping the cellulose and sticking with polyiso.

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