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Community and Q&A

Energy Modeling Agency’s Claims About Spray Foam R-Value and Code

CMObuilds | Posted in Energy Efficiency and Durability on

There is a company posting their service on what is supposed to be a group for professional insulators for providing insulation code approval documentation for new construction with spray foam R13 walls, and R20 attics. The guy who runs the company told me he’d recommend “another inch” when I told him I’m climate zone 6/7 with 9000 HDD.

The website is :

Basically the company provides performance based documentation over prescriptive and uses mainly claimed infiltration reduction as a means of achieving this.

What I’m surprised with was the amount of trade guys that commented in support of this, and how 10 years after this was covered here at Green Building Advisor after Icynene came out with this lower R value for spray foam idea, it is still being used in marketing.

This really just seems like exploiting a code loophole, however I’m not in the foam industry, so am I missing something?

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  1. Expert Member
    BILL WICHERS | | #1

    It's marketing drivel. If they're basing these claims on air leakage, that's really irrelevant. It may be possible to see better performance with spray foam compared to fluffy insulation in an old structure due to the air sealing properties of the spray foam, but the code numbers in terms of R value are basically absolute and DO NOT allow for air leakage. Basically the code numbers specify the R value required regardless of air leakage, so spray foam needs to be compared to an equivalent assembly of the SAME amount of air leakage. What this means is that spray foam R value is equivalent to any other product's R value in reality when the marketing mojo is removed.

    If you do a proper job of air sealing, there is NO difference in heat loss (or gain) between a given amount of spray foam and any other type of insulation installed to the same R value. That's the entire point of R value, to be able to compare different types of insulation in the absence of anything but thermal energy transfer. This is no different than the marketing numbers the radiant barrier people used to use.

    If code says "R38 in this assembly", then you need to install R38 worth of whichever type of insulation you choose. The only exception to that is when you go from the usual "prescriptive" rules in the code to the "U basis" rules, but that usually requires something like continuous insulation where thermal bridging is much reduced.

    Always be careful with data from someone with an agenda to promote. That doesn't necessarily mean that someone is being dishonest, but it certainly gives them an incentive to be creative with their numbers.


    1. Jon_R | | #5

      > ... NO difference in heat loss (or gain) between a given amount of spray foam and any other type of insulation installed to the same R value

      Except that different insulations change R value differently with temperature, time and moisture content. So installed R13 is rarely R13.

      1. 1869farmhouse | | #11

        I had a spray foam contractor (that also marketed himself as an energy consultant) tell me that anything in excess of 2” closed cell foam was a complete waste and would do nothing for performance. He said they commonly add insulation in excess of 2” to meet code requirements, but that it’s simply a delay in codes catching up to the building science and it’s a total waste of money.

        I added 4” of rock wool in the 2x6 cavity in addition to approximately 2.5” closed cell anyway.

        1. Expert Member
          Dana Dorsett | | #14

          >"...anything in excess of 2” closed cell foam was a complete waste and would do nothing for performance. "

          From a FINANCIAL performance that might be true, depending on the required internal rate of return, but that is only due to the very high cost per R of closed cell foam. Closed cell foam runs ~16-20 cents per square foot per R, roughly twice the cost of EPS sheet foam or 4x the cost of fiber insulation.

          From a THERMAL performance point of view it's BS, of course. More-R is better, and measurable.

          >"I added 4” of rock wool in the 2x6 cavity in addition to approximately 2.5” closed cell anyway."

          In most cases that would be financially rational in well under the full lifecycle period of a building, whereas hitting that performance point with just closed cell foam in many cases would be a "pays off never" situation.

          1. 1869farmhouse | | #15

            This guy was convinced that anything above r-15 (even in the attic) was a waste. A “perfect” house in his mind was air sealed perfectly with r-15 all around.

  2. Patrick_OSullivan | | #2

    I can't speak to the accuracy or quality of their work. Whether you call this a code 'loophole' or not is perhaps a matter of perspective. They cite what they're relying on, R405 of the IECC. R405.3 gives you an idea of what they are doing. It's titled Performance-Based Compliance and reads: "Compliance based on simulated energy performance requires that a proposed residence (proposed design) be shown to have an annual energy cost that is less than or equal to the annual energy cost of the standard reference design. Energy prices shall be taken from a source approved by the code official, such as the Department of Energy, Energy Information Administration's State Energy Price and Expenditure Report. Code officials shall be permitted to require time-of-use pricing in energy cost calculations."

    If you can prove performance based on this, all prescriptive and even U-factor alternatives go out the window.

    1. Expert Member
      Michael Maines | | #3

      I have never seen a spray foam manufacturer publish the specifics of a comparison using R405.3, have you? If so, is the airtightness of the reference house code-compliant?

      In my experience, spray foam marketing information is always deceptive. I am not specifically anti-foam, but I am against false advertising and that is all I have seen from spray foam marketers.

      I have literally had a spray foam rep who sits on a national board of spray foam manufacturers argue with me, saying he doesn't know how you could achieve equivalent airtightness without using spray foam. That is the level of misinformation or lack of understanding in their industry.

      1. Patrick_OSullivan | | #4

        > I have never seen a spray foam manufacturer publish the specifics of a comparison using R405.3, have you?


        > If so, is the airtightness of the reference house code-compliant?

        Seems like it. See Table R405.5.2(1). But here's an interesting thing from that table, regarding the proposed air tightness for a design: "For residences that are not tested, the same air leakage rate as the standard reference design. For tested residences, the measured air exchange rate."

        So, if you're going to gain some 'points' (i.e. dollars saved) by drastically reducing air leakage vs. code built, you need to test it.

        To be clear: I'm not saying any of this actually shakes out as being legit, just theorizing what their claims might be.

    2. CMObuilds | | #6

      Im in WI, which is the only non IRC code state in the union I believe, so my compliance process may be different.

      But, one of the two guys associated with this place mentioned proving the assembly is better than a baseline house. Well their baseline house input for air leakage was .67 ACH, in the neighborhood of 12 ACH50 while they calc sprayfoam around 1.8 ACH50. That is just insane that you could use that comparison to prove performance when studies have been done testing basic new construction air leakage. If that is a piece of what they are doing, I would call the process that allows it a loophole since the "baseline" they are using is make believe.

      1. Expert Member
        BILL WICHERS | | #7

        That's nearly as bad as just fudging the numbers outright. It's like an economics professor I had back in college who liked to say "I can write a test to get an average grade of whatever I want it to be". They should be testing a house with something like fiberglass, then the SAME house with spray foam instead and comparing the two. A basic rule of scientific research is to control as many of the variables as you can to ensure reliable results for your tests.

        Like I said earlier, always be careful with data coming from anyone with an agenda to promote.


  3. seabornman | | #8

    We used to use ComCheck all the time to show commercial buildings met the energy code, with less insulation than if using the prescriptive method. Maybe they're just using what's in the code.

    1. CMObuilds | | #9

      They have to show something, and performance method can work and obviously their marketing is a "starting point". So in mild climates with unvented attics I can see it.
      The problem I had is the owner is telling me just another inch for climate zone 6/7, and he meant in addition to the R20 claim, uhh no.
      I don't have a vendetta with the company, more so wanted to open a dialogue about this common practice with the spray foam industry that seems absurd to me.
      And any other insulation industry absurdities, it's not like fiberglass has had our interests in mind.

  4. CMObuilds | | #10

    Then this popped up. The named guy is the owner.

    1. Patrick_OSullivan | | #12

      Always love a reinforcement of the old "if it's too good to be true..." adage!

      1. Expert Member
        BILL WICHERS | | #13

        It's also good to see that the manufacturer is apparently trying to keep things honest here. Note how they say "prohibits the use of the software AND HIS SERVICES". Sounds like they pulled the plug on one of their agents/contractors so they're taking this pretty seriously.

        It's good when manufacturers take action to stop shady practices with people who are supposed to be working on their behalf.


        1. JC72 | | #16

          I got the impression it was an employee.

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