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Community and Q&A

R-38 ceiling and spray foam

jackofalltrades777 | Posted in Building Code Questions on

If one sprayed 5″ of open cell spray foam on a ceiling area, that would equal to around R-17.5, correct?

Now code requires R-38 minimum for the ceiling in this area. There is no “performance value” of R-38 in 5 inches of open cell spray foam, right?

That would be a marketing line bunch of nonsense as 5″ of open cell is R-18 avg. and anyone claiming it is performing like R-38 is lying. How would the code department buy into this nonsense?

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  1. GBA Editor
    Martin Holladay | | #1

    Peter L.,
    Energy experts have been bemoaning the misleading marketing efforts of spray foam manufacturers and installers for many years. Here is a link to my 2010 article on the topic: It’s OK to Skimp On Insulation, Icynene Says.

  2. jackofalltrades777 | | #2


    Thanks for the article. WOW! That is exactly the lie the spray foam company is telling the homeowner. That 5.5" of open cell foam "performs like R-38" when we truly know that it is basically an R-19 ceiling and NOT R-38.

    This is a travesty that a new home will only have an R-19 ceiling when it requires an R-38 ceiling and the spray foam company pulled a quick one on them and the code department.

    I bet the homeowner will feel it via their pocketbook when they get their heating and cooling bills. An R-19 ceiling in 2015 when it calls for a minimum R-38 is completely ridiculous.

    What about reporting the spray foam company to the FTC?

  3. GBA Editor
    Martin Holladay | | #3

    I have been reporting marketers who are not complying with the Federal R-Value Rule to the FTC for many years. Unfortunately, my efforts have not resulted in a discernible uptick in enforcement actions by the FTC. But I urge GBA readers to keep sending those letters and e-mails to the FTC anyway.

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