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Community and Q&A

R21 foil insulation?

Greg Smith | Posted in General Questions on

I admit my surprise when entering GBA this afternoon and being greeted by a banner advertisement for an R21 thin foil reflective film insulation.

I went to the website, but not a lot of technical information there on why the product apparently has such extraordinary performance, as claimed of course.

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  1. GBA Editor
    Martin Holladay | | #1

    Have you got a link to a website or a company name?

    These Google display ads are always a little goofy. First of all, the ads you see are different from the ones I see. (The ads are partly based on your web surfing history. It's creepy.)

    The other funny thing about Google ads is that, when I write a blog that says, "Product X is worthless and the people who sell it are crooks!," there is a pretty good chance that you will see a Google ad for Product X the next time you visit the page.

  2. Greg Smith | | #2


    Unfortunately since I didn't take the ad seriously I didn't pay much attention to the company name.

    I visited the web site just to see what they had to say....typically they didn't say anything worth noting.

    I didn't realize that the ads were partly aimed at me specifically based on my surfing habits. I thought it was just a random Google ad that really landed on the wrong website and I assumed that others would be seeing it as well.

    The obvious irony was just too good to pass up.

    Thanks for the reply and explanation.

  3. Aj Builder, Upstate NY Zone 6a | | #3

    Greg, I got a laugh at that ad too

  4. Jin Kazama | | #4

    Well i must be lucky, because i only get adds with lightly covered ....

    Seriously, I get 90% of time CNC related ads, so i can confirm how scary google is.

  5. Greg Smith | | #5


    It was back this morning.

    Hy-Fi Insulation System

    AJ, my first thought when I saw it was WTH?? Then I laughed and said "gotta check this one out".

    Jin, it is a bit disconcerting for sure to be specifically targeted for ads.

    Low-Cost Hybrid Insulation Designed for High Performance Wall Systems

  6. GBA Editor
    Martin Holladay | | #6

    So the explanation is that most of the R-value comes from spray foam or fiberglass batts (not included).

    Some of the R-value comes from air spaces -- but how are those air spaces (created by the perfectly parallel sheets of radiant barrier foil shown in the illustration) maintained over many years, without the foil warping?

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