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Green Building News

Demilec Spray Foam Named Year’s Best Green Building Product

Heatlok foam uses a new generation blowing agent with a lower global warming potential

A closed-cell spray foam with lower greenhouse gas emissions than conventional formulations has been named best green product of the year at the International Builders' Show. [Image credit: Green Solutions Insulation / CC BY-SA]

A spray polyurethane foam using a next-generation blowing agent that lowers the foam’s greenhouse gas emissions has been named the “best green building product” at this year’s International Builders’ Show.

An announcement from the National Association of Home Builders, which sponsors the annual industry gathering, named a total of 10 products in its Best of IBS Awards. They included Andersen Windows (best in show), solar shingles from RGS Energy, a wi-fi enabled circuit breaker from Leviton, and a “combi furnace” from NTI that provides space heating and domestic hot water.

Demilec’s closed-cell Heatlok HFO spray foam uses a hydrofluoroolefin (HFO) compound as the blowing agent — the part of the mix that produces insulating bubbles in the cured foam. HFOs have a drastically lower global warming potential than the hydrofluorocarbon blowing agents they replace.

In addition, Demilec says, Heatlok High Lift has an R-value of 7.5 per inch and can be sprayed in a 6 1/2-inch lift in a single pass, about three times thicker than closed-cell foam is typically applied. At least some of the oil in the “B” side of the formulation is soya oil rather than a petroleum-based oil.

A second version of the foam, called Heatlok HFO Pro, was developed for the commercial market. Demilec says it has an R-value of 7.4 per inch and creates a Class II vapor retarder and an air and water barrier in a layer 1 inch thick.

The industry is moving  toward HFOs

Demilec is one of several companies that have switched to an HFO in an industry-wide transition that will take place over the next year or two, says Rick Duncan, the technical director for the Spray Polyurethane Foam Alliance, an industry trade group.

HFOs have a Global Warming Potential of about 1 (comparable to carbon dioxide), compared with the 900 to 1000 of HFC blowing agents, Duncan said. Because blowing agents makes up between 5% and 10% of spray foam, the GWP of foam made with an HFO is actually about one-eighth that of HFC-blown foam.

The blowing agent used in Demilec’s foam is a Honeywell product called Solstice. Chemours also makes an HFO blowing agent.

The industry had been preparing for a government ordered ban on HFC blowing agents in foam insulation, but a ruling by a federal appeals court in 2017 struck down the regulation. Even so, manufacturers that had been in the process of developing new HFO formulations continued to work on them. At least 10 states are planning to stick with the 2020 HFC ban despite the federal court rulin, Duncan said.

“We expect to see HFCs banned at the state level in 2020,” he said.

The switch to HFO also has significant practical advantages on the job site. Closed-cell foam is usually applied in lifts of about 2 inches, Duncan said, because thicker applications generate too much heat. At 4 inches, foam may show some internal charring, and beyond 5 or 6 inches, the foam can self-ignite. In a worst-case scenario, the foam catches on fire and burns down the house where it’s being applied.

When an applicator can apply a single layer of 6 1/2 inches, the foam hits R-49, enough to satisfy code requirements for attics in all U.S. climate zones. That feature should reduce installation time by a factor of three, Duncan said.

The Spray Polyurethane Foam Alliance announced the publication of an Environmental Product Declaration for HFO-blown foam last November. The document contains details about the product and helps contractors win credits in green building certification programs such as LEED.


  1. Expert Member
    ARMANDO COBO | | #1

    Great thing to apply ccSF in one application to 6.5" at R49. Is regular Heatlok HFO High Lift an air AND moisture barrier? or just the commercial Heatlok HFO Pro.
    Demilec's Heatlok HFO High Lift website says, "R-value = 7.5/inch*", and the * says "*Aged R-value at 4 inches per ASTM C518"... what does that mean?

    1. Expert Member
      Michael Maines | | #9

      Armando, ASTM C518 is just the test for R-value. It does not specify a thickness; manufacturers can use any thickness they want, it just describes the methods to be used. (I bought a copy for fun.) Aged R-value may mean the LTTR, or long-term thermal resistance, after actual aging for I believe 15-18 months and extrapolating the date to simulate 5 years. Foam will continue to degrade after 5 years so I'm not sure why the industry chose that as the benchmark. "Aged R-value" does not have a specific meaning so I believe it's typical foam corporate marketing bullsh!t.

      I can't help you with the first part of your question.

      1. Expert Member
        ARMANDO COBO | | #11

        Thanks for the explanation, Michael.

    2. Jon_R | | #12

      Thickness effects how fast gases escape - so it has to be specified to accurately report long term values. A one inch thickness will have a lower R value sooner.

  2. user-723121 | | #2

    Any idea what the installed cost is per board foot is vs conventional spray polyurethane. What about odors during and after application, any improvement over conventional. Seems like quite a high R-value per inch, how?

    1. Expert Member
      Dana Dorsett | | #3

      In my area HFO blown foam runs $1.30-1.40 per board foot for medium sized jobs, compared to $1.00- $1.10 for HFC blown foam. In $/bd.-ft terms it's quite a bit more expensive, but in terms of $/R it's not a huge premium at a given R-value due to the higher R/inch but it it's (so far) still more expensive on the few quotes I've seen.

    2. Expert Member
      Michael Maines | | #10

      Doug, the one installer I know who installs it regularly actually charges less than he used to for conventional foam; he says it's because it's so much easier to work with. Other installers I know are still leery about it, want to charge more, require more lead time, etc..

  3. AntonioO | | #4

    Does 6.5" to 7" in one lift mean one "spray application" (meaning coat the surface once) or is a surface sprayed multiple times in "one pass" to achieve this thickness? I'm asking because I wonder how voids would be avoided in a network of truss webs if the material is expanding so quickly and thickly that all surfaces of the truss webs cannot be coated in time. Excuse my unclear understanding of terminology.

    1. Expert Member
      Dana Dorsett | | #5

      Closed cell foam doesn't expand very quickly or very much compared to open cell foam. A totally Zen installer can do it in one steady-hand pass of the gun, but there will be some quick touch-ups (within a few seconds, not minutes) if it looks like any areas got short-changed. In framing bays it's common to "picture frame" ,applying a narrow shot along the perimeter where the framing meets the sheathing to ensure that there are no voids along those areas before filling the center of the cavity, but it all goes in within a few tens of seconds per framing bay. With experienced installers that sort of detail pre-shooting the potential void areas would be attended to on trusses too.

  4. pjpfeiff | | #6

    I had the Heatlok Soy 200+ installed in an unfinished second story about a month and a half ago. I paid roughly $1/board ft.

    I have zero experience with other spray foams, but here is my memory of the odor dissipation: After the first day I could no longer smell it downstairs unless I had the door to the upstairs open. For the first week with windows partway open upstairs the odor was noticeable (but not bothersome) upstairs. After that the smell seemed to be gone and I closed the windows. After a couple of days of windows-closed I could smell it again upstairs. I think it took a full month to pass before I decided that there was no detectable odor from the spray foam whatsoever (windows closed the whole time), and again, it wasn't bothersome. Note that I hesitated to use spray foam mostly due to fears of permanent odor/fumes, so I on high-alert for the odor.

    From what I had previously read about closed-cell foam, I was surprised at how soft the cured foam is. It trims pretty easily with a sharpened putty knife. So I doubt it enhances structural rigidity of the house, but that wasn't something I was going for anyway.

  5. pjpfeiff | | #7

    As a curiosity, the R-value/inch claims are a little bit of a mystery. Demilec provides tables of R-value for various thicknesses, which is says are based on measured K-value at 1 and 4 inches. It's not clear to me what model they used to interpolate/extrapolate to all other thicknesses. With only two data points I assumed something like a linear variation in R/in, but that doesn't work out. In fact the Soy 20o+ and HFO Pro both start at R7.4 for the first inch, and then have decreasing R-value/inch. The High Lift starts at 6.3 for the first inch and then increases per inch.

  6. hudson_valley_gregg | | #8

    A petrochemical is named "greenest" building product. What's next - Roundup being named the "greenest" lawn spray?

    1. Jon_R | | #13

      Maybe. Treat the lawn once with Roundup and you never need to fertilize again :-).

  7. RyanLurie | | #14

    Anyone have opinions on how Demilic HeatLok HFO compares to Icynene ProSeal Eco (MD-R-210) in terms of performance and durability?

  8. mcbane | | #15

    My concrete contractor has recommended Heatlok HFO Pro for underslab insulation. The spec sheet,, says 31 psi compressive strength which seems more than adequate. But the warranty info has a disclaimer about termites. Are there special concerns with use of this type of foam in termite or carpenter ant areas or would performance vs insects be similar to rigid EPS foam? The structure involves no wood so I dont think insects would tunnel through foam to get to the wood. The only concern would be if the insects enjoy eating or nesting in the foam.

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