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Community and Q&A

Bubble-wrap air space 2″ below in-joist radiant floor heating

user-6765846 | Posted in Energy Efficiency and Durability on

My hydronic heating supplier sold me enough foil wrap for the 1600 sq. ft, two storey addition I’ve put on the house. I’ve read conflicting accounts for and against and before I begin or return this material.
I intend to install 2″ styrofoam below slab in the basement addition.
Is bubble wrap efficient/sufficient with an airspace below the radiant floor hearing followed my drywall? or should I add R12 Roxul below this? Or eliminate the bubble wrap and just go with batts?

Thanks Martin, I enjoy your posts and see them frequently in Fine Home Building mag.

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  1. this_page_left_blank | | #1

    Insulation batts will give you a better overall r - value, and be less expensive.

  2. GBA Editor
    Martin Holladay | | #2

    Can you tell us your name?

    For every dollar invested, real insulation will always give you more R-value, and better thermal performance, than bubble wrap.

    Bubble-wrap manufacturers and distributors have a long history of documented exaggerations and lies. For more information, see "Stay Away from Foil-Faced Bubble Wrap."

  3. Expert Member
    Dana Dorsett | | #3

    R12 snugged right up to the radiant tubing or heat spreaders is sufficient for zone isolation between two conditioned spaces.

    A layer of aluminized bubble wrap with 2" of free air both above and below the bubble wrap is too, when the warm side is above the bubble wrap, but is is a bigger PITA to install in such a way that it actually delivers the performance.

    It's not clear why this sort of product is regularly recommended for radiant floor applications. It's really not particularly useful or appropriate when there is an entire wood framing bay to accommodate relevant amounts of cheap fiber insulation.

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