GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Closed cell spray foam – Demelic Heatlok Pro HFO

BrooklynFlatRoof | Posted in General Questions on

My contractor is proposing to use Demelic Heatlok Pro HFO on the underside of my roof sheathing and the walls.  

Is this a good brand of CC Spray foam insulation?  

I attached the product sheet.

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. pjpfeiff | | #1

    Not sure I have a lot helpful to say, but I had flash & batt done with a similar Demilec product (Heatlok Soy 200+) with 2" on the underside of the roof and 1" on the walls (followed by mineral wool). These products seem to have higher R-value/inch than other foams, so I was able to get to ~R38 roof with 2" + R23 batt. One thing that surprised me (and not sure if it applies to Heatlok Pro, but probably) is that the cured product is somewhat soft. You can trim it easily with a sharpened putty knife. Purely based on what I read about CC foam I expected it to be hard and rigid.

    1. Jon_R | | #2

      Avoid foam companies that publish only an extremely misleading "initial R value" (as I see for 200+). Or don't define "aged thermal resistance" (as I see for their HFO). Probably 90 days of elevated temp aging is used - this is still ridiculous, a 15 year "very long term" estimate based on thin slicing would be reasonable. R6.0 is closer to the right number than R7.4.

    2. Expert Member
      BILL WICHERS | | #3

      Closed cell foam is pretty hard, you can literally snap off pieces with a big POP sound. It's tough, that's why no one wants to overfill and have to trim the stuff -- it's a pain to cut through it. Open cell is a little soft, and MUCH easier to trim. If the material you saw was a little soft, it may have been open cell foam and not closed cell foam.

      I agree to not go with "initial R value". You want "aged" R value. This is the thing that got the polyiso guys in trouble some decades ago. No one cares what the R value is in the first month. What matters is what the R value will be 5, 10 years from now.


      1. BrooklynFlatRoof | | #4

        According to the data sheet the aged thermal resistance per inch is 7.4ft^2hF/BTU. Is that the same as R-value?

        1. pjpfeiff | | #6

          Yes. I'm not sure if the others are referring to the fact that the R-value/inch listed is higher for the first inch (7.4) than for additional inches (i.e. R-value at 3.5" is 23 which means that the additional 2.5" is at R6/in). The only explanation I can dream up for that is that the insulating value is actually better at large temperature differentials than at small, but I really don't know why that is.

      2. pjpfeiff | | #5

        I worried it was open cell (although I specified closed and got billed for it), so I took a piece and put a drop of water on it, which beaded up and never soaked in. I also set a piece in a glass of water and it never took on any water. Presumably that confirms it is closed cell, but if you have a better way to confirm it, let me know. It's very important to me that it is closed cell.

        As J Steven noted, the data sheet specs "aged" thermal resistance, so I think we're ok there unless the company is being especially deceptive. Also, I thought the deal with polyiso is that it's insulating value is reduced for low temperatures, not that it necessarily looses R-value over time. Or maybe it has had both problems?

        1. Expert Member
          BILL WICHERS | | #9

          The early blowing agents used in the manufacture of polyiso didn’t have the “R value goes down in cold weather” problem — that’s a new issue with some of the newer blowing agents. Polyiso has always lost R value a little with time as the blowing agent gradually diffuses out of the material. This reduction in R value stabilizes over time, so the R value is highest right after manufacturer, then gradually drops to a lower, long-term “aged” R value. XPS also drops in R value over time. Note that the drop isn’t huge, but it is there. EPS does NOT have this property.


  2. Expert Member
    Dana Dorsett | | #7

    >"...on the underside of my roof sheathing and the walls. "

    Demilec is one of the larger players with good products, provided the installers are well trained and go by the book.

    But installing closed cell foam between studs is a pretty serious waste, given the high financial and environmental cost (even for HFO blown foam) for only very marginal thermal benefit. Do the math:

    Whether under the roof deck or in walls in a "flash'n'batt", using anything more than the minimum required for dew point control at the foam/fiber boundary is pretty much wasted.

    Saving the high R/inch foam budget for continuous layers where the full potential is realized, unbridged by framing improves the benefit side of the cost ^ benefit balance.

  3. BrooklynFlatRoof | | #8

    If I want to watch while the contractor is spraying will a honey well north vapor cartridge suffice?

    I'm going to stay out of the immediate spray area so a tyvek suit probably isn't necessary.

    1. Expert Member
      Michael Maines | | #10

      J Steven, no, you should have a supplied-air respirator and full-body suit. Isocyanate exposure isn't something to mess around with.

  4. BrooklynFlatRoof | | #11

    The contractor showed up to spray Friday and I went to his truck to see the type of foam he was using. Sure enough, it wasn't the Demelic Heatlok Pro HFO he said he would spray. Instead it was Spray Market SPM-200HL. He insisted it was the essentially the same stuff, just that his supplier ran out of Demelic Heatlok. I look up the aged thermal resistance of the SPM-200HL and it was 6.3 R-val at 1" and 26 R-val @ 3.5" . So less R-value at 1" but somehow greater R-val at 3.5"????

    I was frustrated and vented to the contractor, who insisted it was the same thing. I needed to get this done, so I let them get to work.

    By and large the guy spraying did a great job. Not a lot of overspray and his assistant made sure my tools and supplies were moved & covered up.

    Near the end of the job, the contractor claims he's running out of material and can't finish the job. I think he's lying b/c his workers told me he's got another small job to do on Friday and the spray foam distributor is closed at this point. 430pm on a Friday. We argue a bit about this, but he say's he'll come back Monday to finish the job and spray some extra areas b/c of the inconvenience.

    We agree to have his crew come back Monday to finish. I point out some areas near the rim joist that he didn't come down low enough on and after some discussion he agreed to spray those as well. I have not paid them yet.

    I'm upset that the contractor bait and switched the product on me. At 1" the SPM-200HL has 85% of the R-value than Demelic Heatlok Pro. Will the contractor accept 85% of the agreed upon contract amount? I'm going to call the local distributor to find out the price difference. If it's significant, I'm going to ask for a discounted contract. Or request they spray foam on the walls where the bedrooms are located for some moderate soundproofing. The building is attached on both sides.

    Anyway - here are some pics from the job and the SPM-200HL data sheet.

  5. Jon_R | | #12

    Every other manufacturer I've seen specifies a lower R value for short term aged at 1" - because the gases leak out quicker when it's thinner. No idea why Demelic would see the opposite behavior (higher R value when thinner). But note that none of the numbers are accurate anyway (you want a lower "very long term aged R" which you won't get from the manufacturers).

  6. user-3258290 | | #13

    Not the same, not at all. You were quoted a foam blown with HFOs, which has a global warming potential of ~1. Instead they used a product with blown with HFCs with a GWP of 1000. At the very least, please don't have them spray more of it, especially on interior walls just for soundproofing.

    1. Expert Member
      Dana Dorsett | | #14

      >" At the very least, please don't have them spray more of it, especially on interior walls just for soundproofing."


      Closed cell polyurethane foam is one of the least green insulating materials in common use. Even the HFO-blown stuff isn't great, but the HFC blown stuff is a crime, LITERALLY contraband in the signatory countries to the Kigali Amendment to the Montreal Protocol that went into effect this year!

      Regarding the higher R-/inch at greater thicknesses- the reasons are complicated, but that is not a rare phenomenon for closed cell foam insulation.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |