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Community and Q&A

Mineral Wool R-value by temperature

natesc | Posted in Energy Efficiency and Durability on

Does anyone know if there is any information available that shows the performance of mineral/rock wool by temperature? has this for polyiso:

I am wondering if there is something similar for mineral wool.

A few other links I have found –

John Straube did an advertisement for roxul where he said that mineral wool performs better the colder it gets. I am wondering if there is any difference between fiberglass and mineral wool as temperature decreases.

Intuitively I would think not. Extrapolating the fiberglass chart, if an R-13 batt performs as R-13 @ 60F, and R-14 @ 10F, an R-23 batt would perform as roughly R-25 at 10F.

Thanks for any information.

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  1. charlie_sullivan | | #1

    I would expect it to behave the same as fiberglass. The phenomena are the same in those two. The weird behavior of polyiso is presumed to be because of the gas that fills the bubbles in it, whereas the gas in fiberglass and mineral wool is just air.

  2. BillDietze | | #2

    It behaves like fiberglass and increases the R value as the temperature drops. See

  3. BillDietze | | #3

    Nathan, here's a much better reference. If shows mineral wool performance vs. temperature for residential applications and compares it against polyisocyanurate foam board.

    1. severaltypesofnerd | | #6

      Do you have an updated sheet of Roxul temperature performance (the old link is dead)?

  4. natesc | | #4

    Bill, thank you for the links. The Roxul sheet is exactly what I was looking for.

  5. Expert Member
    Dana Dorsett | | #5

    The accumulated moisture levels affects performance too, and as I understand it that is built into the pro-versions of WUFI, not that it's going to matter much in most applications, though in high-R assemblies with specific performance targets (such as PassivHaus) it might.

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